research article assessment of the efficiency of...

Research ArticleAssessment of the Efficiency of Consolidation Treatmentthrough Injections of Expanding Resins by Geotechnical Testsand 3D Electrical Resistivity Tomography

T Apuani1 G P Giani1 M drsquoAttoli2 F Fischanger3 G Morelli3

G Ranieri4 and G Santarato5

1Department of Earth Sciences ldquoArdito Desiordquo University of Milan Via Mangiagalli 34 20133 Milan Italy2Geosec Srl Via G di Vittorio 41b 43044 Collecchio Italy3Geostudi Astier Srl Via A Nicolodi 48 57121 Livorno Italy4Department of Civil Engineering Environmental Engineering and Architecture Via Marengo 2 09123 Cagliari Italy5Department of Physic and Earth Sciences Via Saragat 1 44122 Ferrara Italy

Correspondence should be addressed to G Ranieri granieriunicait

Received 20 December 2014 Accepted 13 May 2015

Academic Editor Ahmed El-Shafie

Copyright copy 2015 T Apuani et alThis is an open access article distributed under theCreativeCommonsAttribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The design and execution of consolidation treatment of settled foundations bymeans of injection of polyurethane expanding resinsrequire a proper investigation of the state of the foundation soil in order to better identify anomalies responsible for the instabilityTo monitor the injection process a procedure has been developed which involves in combination with traditional geotechnicaltests the application of a noninvasive geophysical technique based on the electrical resistivity which is strongly sensitive topresence of water or voidsThree-dimensional electrical resistivity tomography is a useful tool to produce effective 3D images of thefoundation soils before during and after the injections The achieved information allows designing the consolidation scheme andmonitoring its effects on the treated volumes in real time To better understand the complex processes induced by the treatmentand to learn how variations of resistivity accompany increase of stiffness an experiment was carried out in a full-scale test siteInjections of polyurethane expanding resin were performed as in real worksite conditions Results confirm that the experimentedapproach by means of 3D resistivity imaging allows a reliable procedure of consolidation and geotechnical tests demonstrate theincrease of mechanical stiffness

1 Introduction

The application of soil consolidation techniques using resinshas greatly increased over recent years especially followingthe development of new materials and methods specificallystudied for this field of application The purpose of the resin-based consolidation techniques is to remove the causes ofsettlements of the foundations by injecting an expandingpolymer material into the ground

The first procedures implemented date back to the secondhalf of the 1950s in the United States and to the 1990s inEurope Now they are available on the market for a variety ofapplications Among the most popular procedures employedthere are consolidation techniques involving the free

diffusion of resin in the ground and mixed techniquescombining the resin injected with a load-bearing structuralelement connected with the existing foundation for thetransfer of the load to a given depth The interest arousedby this procedure lies in its high efficiency as shown by thefollowing facts (i) it provides an effective solution even inthe long term (ii) it is minimally invasive as it allows rapidityand flexibility of the treatment and the ability to work innarrow spaces using streamlined and compact instruments(iii) it is environmentally compatible

Settlements of the ground subjected to the foundationload are often due to periods of drought alternating withheavy rainfalls sewer leaks heavy vehicle traffic excavationsclose to the building and growth of tree roots and variation of

Hindawi Publishing Corporatione Scientific World JournalVolume 2015 Article ID 237930 13 pageshttpdxdoiorg1011552015237930

2 The Scientific World Journal

AES8AES8AES3

AES7a

b1

AES8a

595771

595771

596771

596771

597771

597771

598771

598771

599771

599771

600771

600771 4955

029

4956

029

4957

029

4958

029

ParmaTest site

AostaTrento

Genova

TorinoMilano

TriesteVenezia

Bologna

Firenze

AES3-Agazzano SubsynthemAES7a-Niviano unitAES8-Ravenna Subsynthem

AES8a-Modena unitb1-Alluvial sedimentsTest site

(a)

(b)

(c)

N0 500 1000250

(m)

Ancona

Figure 1 (a) Test site location in Italy (b) Geological map of the area (ISPRA Sheet 199 coordinates are in meters ED50) (c) View of thetest site

applied loads The interaction between water and foundationsoil is undoubtedly one of the most important mechanismsand a critical factor for all types of ground Clayey soils infact have the capacity to absorb large quantities of waterwhich leads to a considerable increase in volume On theother hand loss of water manifests itself in a decrease in thevolume of the ground If periods of heavy rain alternate withperiods of drought the volume of the ground is cyclically sub-jected to swelling and shrinkage [1] which leads to the cre-ation of voids hence to the risk of differential displacementGranular soils in contrast exhibit greater permeability andthewater circulates freely possibly transporting fine particlesThis circulation if sufficiently intense can progressively leadto the creation of voids and cavities which often contributeto the phenomenon of foundation settlements

Many factors affect the process of soil consolidation byinjections of expanding resins on one side the geotechnicaland hydrogeological context and on the other the specificresin-based consolidation technique Although the use ofresin-based consolidation techniques is more and moregrowing the full comprehension of the process involved isnot completely achieved yet Some authors have presentedcase studies in different geological contexts using specificresin and injection techniques [2 3] Some studies aredevoted to explore the variation of geotechnical hydrogeo-logical and geophysical properties of soils during and afterthe treatment by a back analysis approach on dedicated testsites [4 5] or real application cases [6 7] Only few authorshave applied a theoretical approach to predict the treatment

efficiency [8] It results that the topic needs to be scientificallyinvestigated further

Due to the complexity of the system (soilresin) it isunavoidable that each study is dependent on the geotechnicalcontext as well as on the product and procedure used To shedlight on the observed correlation between geotechnical andgeoelectrical response variations due to resin injection thatallow to use time-lapse resistivity surveys to suitably monitorthe injection process a full-scale field test was planned Hereinjections of two-component polyurethane expanding resinwere executed following the procedure already described bySantarato et al ([6] see also [9]) Detailed geotechnical testswere performed before during and after the injections andrepeated three-dimensional electrical resistivity tomography(3D-ERT) was performed as well

The test site was purposely selected to analysewhat occursin recovery of foundation settlements by means of resininjection in cohesive soils which is a very frequent althoughspecific occurrence in the consolidation practice

2 The Test Site Geological Outline

A full-scale test site was set up where resin injections werecarried out in compliance with the usual procedure followedin real cases of settlements of building foundations

The test site is an agricultural field presently uncultivatedlocated south-west of Parma in the Municipality of Collec-chio (Figures 1(a) and 1(c)) From the geological point of viewit lies in the foredeep of the Apennine chain which rises to

The Scientific World Journal 3

the immediate south of the site location and develops ina NW-SE direction bordering the southern side of the PoValley plain

The geology of the area (Figure 1(b)) is characterised bya marked accumulation of quaternary alluvial sedimentswhich lie in simple discordance on the substratum of latePliocene and early Pleistocene marine sediments The depthof these sediments narrows down noticeably moving towardsthe SW and reaches its minimum depth near Collecchiotown In the site location the shallowest stratigraphic unitbelonging to the upper emiliano-romagnolo Synthem (AES)is the Ravenna Subsynthem (AES8) [10] with a maximumthickness of about 20m The AES8 unit is constituted bygravel sand and layered silts alluvial fan and intravalleyterraced deposits or deposits of the secondary hydrographicnetwork covered by clay silts which represent palaeosoils atvarying degrees of evolution local lenses of gravel and sandreach on average a thickness of 3 metres

The hydrogeological arrangement of the area is outlinedin three complexes the gravelly-sandy upper complex (A)the sandy-clay complex (B) and the basal clay complex (C)The coarse horizon of the AES8 unit constitutes the firstmain aquifer (A) and the water level in the site locationwas estimated to lie at about 10m below ground level (bgl)(regional monitoring network)

3 Hints about the ERT Geophysical Method

Electrical resistivity of loose sediments depends mainlyon their water content besides their texture and mineralcomposition as it is well known (among many others [11ndash14]) so that electrical resistivity is the best-suited geophysicalparameter that can be used for characterisation of watercontent status and of its changes in space and time

The three-dimensional (3D) electrical resistivity tomog-raphy (ERT) is a geophysical imaging method which allowsdetermining the distribution of electrical resistivity in thevolumes of the investigated subsurface Electrical potentialsproduced by a continuous current input into the soil aremea-sured using two couples of electrodes driven into the soil thefirst one to feed a continuous electric current and the secondone tomeasure the potential drop whose value is determinedby the distribution of resistivity in the investigated subsoil(and by the reciprocal positions of the electrodes obviously)The generalized use of the modern automatic multielectrodegeoresistivity meters allows to manage many (tens and evenhundreds) electrodes laid out in the surveyed area so thathundreds and event thousands of measurements can beharvested in very short times [15] In order to obtain the dis-tribution of resistivity in the subsurface inversion strategiesare used These involve first the discretization of the investi-gated subsurface into (generally hexahedral) blocks and thenumerical solution through finite element techniques of theLaplacersquos differential equation which rules the phenomenon

nabla2119881 = 0 (1)

where119881 is the electrical potential at a distance 119903 from a pointsource of steady electrical current 119868 The whole dataset ofmeasurements is then simulated and compared to data by

means of an optimization procedure according to a recursiveleast squares approach so that the resistivity distribution inthe investigated subsurface is estimated For the whole cycleof inversions a customised version of ERTLAB was usedwhich uses a robust approach to least squares minimisationas described byMorelli and LaBrecque [16] and the a priori1205942statistic as a misfit criterion therefore convergence is reachedwhen 1205942 approaches the number of data Any lithologicalvariations states of soil saturation cavities buried structuresor other anomalous bodies which are characterised bydifferent resistivity values or ranges are therefore imagedand can be highlighted in compliance with the specificinvestigation depth and the resolving power of this method

Based on these considerations ERT as an indirect non-invasive technique is ideal for monitoring the injectiontreatment while it is being carried out The mechanism bymeans of which the polyurethane resins (which have highelectrical resistivity) are distributed in the soil normallyfollows a dendritic pattern (see Figure 7) Therefore thefilaments of resin do not have any significant impact on theflow of electrical current in the subsurface as a consequencethe resistivity variations observed along timewhile injectionsare carried out are to be attributed to the effect of the removalof the interstitial water andor the filling of voids as a resultof the compaction triggered by the expansion of the resin

4 Methodology Design ofInjection and Investigations

In the test site two adjacent square plots each measuring6m per side were selected covering a total surface area of6 times 12m2 (Figure 2) Consolidation treatments were carriedout in the first plot while no treatments were executed in thesecond one kept undisturbed for comparison purposes

In order to assess the modifications brought about byinjecting resin into the ground both areas were subjectedto geotechnical and geophysical testing aimed at identifyingthe soil nature and the relative strength and deformabilityparameters The geotechnical in situ tests have includedcone penetration tests CPTU and plate-bearing tests whichwere carried out before and after the injections In additiongeotechnical laboratory tests were performed on samples ofldquoundisturbedrdquo soil (direct shear test andunconfined compres-sive test) and on ldquoresin-treatedrdquo soil (unconfined compressivetest) Likewise in compliance with worksite practices 3DERTmeasurements were carried out in order to acquire evenin volumes of soil not directly controlled by geotechnicaltesting the information that is normally necessary for thetreatment design of the consolidation procedure and itsmonitoring in real time The strength and deformabilitycharacteristics of soil before and after the procedure deducedby the geotechnical surveys were thus compared with thegeophysical imaging results

The consolidation treatment involved executing 39 injec-tions carried out mainly at a depth of 150 cm below groundlevel (bgl) along the perimeter of the 6 times 6m2 area involvedin the treatment process with a distance between centres of 1metre A number of repeat injections in the same point were


V1

V2

V3

V4

D1

Cp1

Cp2

Cp3

F1-5

Ci2pre

Ci3pre

Ci1pre

Ci5post (b) Ci4post VM1VM2

Cp4Ds1

Ci3post

Ci1post

Ci2post

T1

T2 Cp7

Cp5

GDs2

B

F

A

C D E

(a) (c)

(d)

(e)

Posttreatment testsPretreatment tests

Cp6

460m

630

m

60

m

CPTU

3D electrodes

Sampling sitePlate-bearing test

InjectionsSingle

Double

F7 injectionIn situ density test

pit A z = minus110 cm

pit B z = minus130 cm

Side (a) 24kg a minus15mSide (b) 33kg a minus15m

Side (c) 17kg a minus15e minus25m

Side (d) 25kg a minus15e minus25mSide (e) 50kg a minus15 +50kg a minus25m

Figure 2 Map of the test field showing location and specifications of samplings and geotechnical-geoelectrical tests The test or samplingidentity codes concern V = balloonmethod density test D = sand conemethod density test VM=posttreatment balloonmethod density testDs = posttreatment sand cone method density test Cp = plate-bearing test F = sampling with perforating punch CPTU = cone penetrationtest

carried out at a depth of 250 cm from ground level The resinused called ldquoEco-Maximardquo has considerable compressivestrength in addition to good tensile and buckling strengthUniaxial compressive tests conducted by the University ofParma and at the facilities of the RampS laboratory of Parma onresin samples of different densities (from 40 to 200 kNm3)produce strength values between 133 and 2420 kNm2

Geotechnical surveys were carried out in three consecu-tive stages

On the day dedicated to consolidation treatment CPTUstatic penetration tests were carried out before duringand after the injections for a total number of 27 tests (9preliminary 9 intermediate and 9 posttreatment tests) Fur-thermore cores of treated and nontreated soils were sampled(Figure 2) The whole consolidation phase was monitoredusing 39 repeated 3D ERT surveys corresponding to theintermediates carried out following each injection of resinAn array composed of 48 electrodes spaced 1 metre apartwas laid out over an 8m times 16m rectangle surrounding thetwo disturbed and undisturbed plots in the test site Thislayout guarantees an investigation depth of about 3m whichincludes the whole volume of soil affected by resin injectionas purposely designed to simulate realistic working condi-tions In such specific this depth range and contenxt [6] thereduction of resolving power is negligible if compared withconventional ERT data acquisition by means of a regularlyspaced electrode grid

The comparative analysis of all the surveys made itpossible to identify the lithostratigraphic properties of the siteand indirectly to obtain specific soil parameters by preservingthe soil from invasive excavation It is obvious that both coresampling and penetration tests led to some modifications

although minimum to the mechanical characteristics of theground nearby the investigation points This was duly takeninto consideration when selecting the areas for executingsubsequent tests

In a second stage excavation and soil removal werecarried out down to a depth of 110 cm bgl (pit A in Figure 2)in the area adjacent to the ground treated with resins Theaim was to obtain exposed stratigraphic sections and aboveall a level surface on which to carry out geotechnical densitytests and plate-bearing tests in addition to pretreatmentcharacterisation

A third investigative stage consisted in excavating aportion of soil down to a depth of 130 cm bgl (pit B inFigure 2) thus intervening on the volumes of soil affected bythe injections It was therefore possible to directly observe thedistribution of the resins in the soil and let exposed a levelsurface on which to sample and to carry out the same in situtests before and after treatment

5 Geotechnical and Geophysical PretreatmentCharacterisation of the Test Site

The information about the nature of the subsurface thestratigraphy and the grain size distribution of involved soilsderives from the joint analysis of (i) surveys conducted onthe pit A sampling and geotechnical identification tests (ii)CPTU penetration tests (iii) pretreatment 3D ERT survey(iv) geotechnical laboratory and in situ tests aimed to obtainsoil strength and deformability

(i) Excavation of pit A brought to the light continuous anduniform stratigraphic characteristics all along the perimeterTwo horizons can be discerned the first at a depth of


approximately 40ndash50 cm consists of brown clay and silt witha uniform particle size with sparse millimetric clasts Thesecond horizon extends to the bottom of the pit and ismade up of brownish-yellow plastic and very firm silty claysRoot structures with diameters measuring in the region ofcentimetres are found down to 70 cm bgl The results of thegeotechnical tests refer to samples taken at a depth around150 cm The investigated soil can be defined as silt with clayslightly sandy or rather CL according to the USCS (UnifiedSoil Classification System adopted by [17]) organic contentO = 5ndash10 nonuniform (coefficient of uniformity Cu =9ndash18) medium plasticity (liquid limit WL = 40ndash53 andplasticity index PI = 22ndash26) with water content W = 13ndash23 in natural conditions firm or locally very firm Densitytests carried out in situ using the sand cone method [18]and rubber balloon method [19] or in laboratory using thedrive cylinder method [20] provide weight values of naturalvolume 120574

119900= 193 plusmn 07 kNm3 dry weight volume 120574

119889= 161 plusmn

09 kNm3 a calculated porosity 119899 = 34 plusmn 5 the measuredabsolute specific weight being 120574

119904= 253 plusmn 05 kNm3 (mean

values plusmn standard deviation)(ii) The nine CPTU tests performed preliminary to

the injections reached a maximum depth of approximately280 cm bgl Plots in Figure 3(a) display the averaged profilesand data dispersions (grey areas) for cone resistance (119876

119888)

friction ratio (119877119891) and pore pressure (119906

2) parameters Both

cone resistance and friction ratio values show a good con-sistency at the same depth for different CPTU tests Onlyvariations of the order of 20 are observed which are dueto slight lateral inhomogeneity of the layers The maximavariation in 119876

119888is recorded at a depth of 160 cm bgl while

that in119877119891is located at about 30 cmbgl where tree roots were

locally revealed by direct surveys conducted on pit A Thepore pressure parameter shows wider variations probablyrelated to local conditions and to the higher sensitivity ofit to different injection procedures For this reason a strictcomparison of the absolute values of 119906

2among tests is not

achievable anyway in general all tests show a weak gradualincrease of the pore pressure with depth

(iii) Figure 3(b) shows as a fence diagram the distribu-tion of resistivity below the layout of electrodes as obtainedby 3D inversion of the data acquired before injections Theinformation provided by the 3D ERT is coherent with theevidence provided by the excavation and by the CPTU testsperformed before the injection sequence

The following electrostratigraphic layers consistent withthe penetrometric test results and with the usual range forloose lithologies in alluvial plains [21] can be seen

(i) a shallowest layer down to 40ndash50 cm aerated soil dis-turbed by farming activities defined by geotechnicalinvestigations as brown silt with clay with resistivityin the range of 50ndash60Ohmsdotm characterized by thelowest values of cone penetration resistance a depthincreasing side friction (119865

119904) and the highest friction

ratio (119877119891)

(ii) an intermediate layer from 40 to 150 cm plasticsilty clays with resistivity values in the range 20ndash40Ohmsdotm 119876

119888values ranging from 3 to 7MPa a

friction ratio (119877119891) slightly increasing in depth

(iii) a more resistive layer below about 24m silt withclay slightly sandy characterized by an increase inresistivity up to values around 70Ohmsdotm average 119876

119888

values of 8MPa with higher values of both resistivity(up to 100Ohmsdotm)and cone resistance (up to 10MPa)related to the presence of larger particle size soils(partially saturated sand and gravel)

Further investigations and discussion will be focused on theintermediate layer

Further geotechnical laboratory and in situ tests wereperformed on samples referring to the intermediate layerbetween minus100 and minus150 cm corresponding to the moreconductive lithology (25ndash30Ohmsdotm) associated with themore abundant presence of fine material Soil shear strengthparameters obtained by direct shear tests [22] on undis-turbed samples furnished respectively are peak cohesion 1198881015840= 42ndash74 kPa and peak friction angle 1206011015840 = 17ndash21∘ Unconfinedcompressive tests executed before and after treatment wereconsidered a more suitable tool for evaluating the effective-ness of the treatment in a similar way to that suggestedin the assessment for checking inertization treatments [23]and considering the engineering problems for which thetreatments are executed The investigated soil has a uniaxialcompressive strength 120590

119888= 208 kPa (mean value of 6 samples)

with 120590119888= 159ndash464 kPa and deformation modulus calculated

at 15 of 12059011988811986415 = 140ndash316MPaThe high extreme values of

strength and stiffness are ascribable to samples with a certainamount of disturbance caused by the sampling process

The elasticity values obtained on the sampling scale areconsistent with the behaviour detected by means of the plate-bearing tests executed at the bottom of the pit B (119911=minus130 cm)following the CNR Mod T0116A [24] standards using a 30cm diameter plate executing two load cycles with maximumload 035MPa spaced out by a rapid unload phase The insitu tests provide the following compressibility moduli119872

119864=

139ndash224MPa and1198721015840119864= 266ndash311MPa calculated on the first

and second load curve respectively

6 3D ERT Monitoring of the Injection Process

The whole consolidation phase was monitored using 3DERT surveys together with the acquisition of 39 sets of ERTmeasurements corresponding to the intermediates carriedout following each injection of resin

In a previous paper [6] the large-scale variation of the sub-soil resistivity was described during a resins injection treat-ment in real worksite conditions For the test site describedhere we will show selected ERT monitoring images focusedon a smaller scale in order to infer by means of a moredetailed view the dynamics of subsoil resistivity changes thatfollow the resins injection process and possibly to connectthese features with evidences coming from geotechnical dataWe will therefore describe the changes in resistivity valuesand distribution of a selected portion of the test site subject to


Cone resistance Qc (MPa)

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

0 0

0 10 20 30 40 50 60 70 80 90

2 4 6 8 10 122 4 6 8 10 12 14 16

minus24

minus28

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28

Qc min (MPa)Qc average (MPa)

Qc max (MPa)

Pore pressure u2 (kPa)

u2 min (kPa)u2 average (kPa)

u2 max (kPa)

Rf min ()Rf average ()

Rf max ()

Friction ratio Rf ()

(a)

108

64

2

80

72

64

56

48

40

32

24

YX

Z

1416

12

0

0

6

8

42

minus4

minus1

minus3minus2

Resis

tivity

(Ohm

m)

(b)

Figure 3 (a) Cumulative results of CPTU geotechnical tests performed before injections cone penetration resistance 119876119888 friction ratio 119877

119891

and pore pressure 1199062 (b) fence diagram of the 3D ERT resistivity model before injections


Cl1PRE

E44 E43 E42 E41

F9 F9b

F7 F7b

F5 F6F8 F8b

Ci6POST

CPTU6

24kg

24kg

25kg a minus150m

25kg a minus150m

25kg a minus150m

E38

E40

E39

+25kg a minus250m

+25kg a minus250m

+25kg a minus250m

aminus150

m

aminus150

m

(a)

minus150

minus300

001830

1840

1850

1860

1865

300

150

0000X

Y

Z

1855

1845

1835

360

365

370

375

380

385

Res diff ()

minus20

minus15

minus10

minus05

(b)

Figure 4 (a) Detail of the site area being analyzed for discussion of ERT time-lapse results (cyan electrodes red injection points) (b) Detailof the resistivity changes at time T1 after injection F7 in the neighborhood of the injection point F7 (yellow dot) Horizontal slice at 119911 = minus15m

a sequence of adjacent injections monitored by consecutiveERT intermediate readings This portion is representative ofall other sets of injections and ERT measurements that wereacquired on the site

We focus on the ERT results and images within a timeframe that covers a sequence of 3 injectionsmdashreferred belowas F6 F7 and F8 spatially adjacent at 1m from each other(Figure 4(a))mdashselected on the basis of the following criteria

(1) these are the very first injections that were performedon the site in order to operate in undisturbed back-ground conditions to get a reliable reference for theresistivity changes

(2) the injected volume of soil is located close to onecorner of the electrodes arrangement within thebest sensitivity portion of the investigated subsurface[6] The array of electrodes is 1m apart from theinjections

(3) the three injections were performed at the samedepth minus150m bgl using a similar amount of resins(24-25Kg) with the injection sequence T1-F7 T2-F8and T3-F6

(4) injections and subsequent ERT measurements wereall made in the same day within few hours with thesame spread of electrodes the same cables arrange-ment and the same instrument this reduces the pos-sibility that ldquoexternalrdquo factors can affect the resistivitydata processing

All 3D ERT measurements were acquired by using a 10-channel IRIS Syscal Pro georesistivity-meter and selecting thepole-dipole array as it is the most suited in terms of resolvingpower for this specific acquisition of a 3D information [6]asymmetrical response of this array was compensated by

acquiring both ldquodirectrdquo and ldquoreverserdquo sequences of measure-ments All possible combinations of receiving dipoles withlengths 1 2 3 4 and 5 meters were acquired for each trans-mitting electrode of the spread A whole number of about4600 measurements were acquired for each intermediateand before inversion submitted to data quality control andpreprocessing steps in order to remove low signal to noisedata coming from the most unfavorable arrangements ofelectrodes Inversion was then performed by using a finiteelement mesh of 05 meters size in 119909 119910 and 119911 directions thatis half of the spacing between contiguous electrodes In allinversions carried out in compliance with the smoothness-constrained inversion approach [25] we used as startingmodel a homogeneousmodel of 55Ohmsdotmwith an estimatedstandard deviation error for the datasets equal to 2 Theinversions converged after 6 iterations using as a misfitcriterion the a priori 1205942 statistic in this case equal to about3900 the number of measurements retained after rejectinglow-quality data as specified above

The Figure 4(b) shows a horizontal slice and the percentvariations in resistivity occurred in the neighborhood ofan injection point (yellow) at T1 (after injection inF7) withrespect to T0 An increase of resistivity is observed in the areaof soil close to the injection point while areaswith decrease inresistivity are present when moving away from the injectionpoint

In Figure 5 we show the variations of resistivity values attimes T1 T2 and T3 with respect to their preinjection T0values in the 50 times 50 cm cells at different intermediates for aportion of themesh around the F7 point underwhich the firstinjectionwas performedThe reported statistics refer to threeprogressively increasing volumes of soil in the neighborhoodof point F7 with edges of 1m 2m and 3m respectivelyResults are displayed on a vertical 119909119911 plane passing throughthe F7 injection point A similar behavior can be observed


Injection

ElectrodesInjection

CPTU Injection point

F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

Displayed section

80

65

50

35

0

15

30

20

minus15

minus30

Where(a) 1m times 1m times 1m

(b) 2m times 2m times 2m

(c) 3m times 3m times 3mControl volumes around F7 injection point

343 (a) 371 (b) 426 (c) 568 (a) 466 (b) 458 (c) 577 (a) 469 (b) 450 (c) 571(a) 468 (b) 455 (c)

Res diff()

05m

1m2m

3m

Average resistivity (Ohm m)




(Ohm m)Res

(T0) preinjection (T1) after F7 injection (T2) after F8 injection (T3) after F6 injection

Figure 5 Variations of resistivity values at different intermediate times T1 T2 and T3 with respect to their preinjection T0 values in the 50times 50 cm cells for the portion of the mesh around the F7 point Average resistivities are calculated in increasing cubic volumes (1m averagevalue (a) 2m average value (b) and 3m average value (c)) Injection characteristics in F5 F6 24 kg at minus150m in F7 F8 F9 25 kg at minus15m+ 25 kg at minus25m

in 119910119911 direction there are no preferential directions of resinsspread due to injection nozzles orientations since injectionpipes are simply open at the base so any preferential pathwayof the resins is related only to the structural characteristics ofthe soil

Figure 6 illustrates the average resistivity at differentintermediates (time) for volumes of 1m 2m and 3m size inthe neighborhood of the F7 injection point

The above data and images allow to draw the followingconsiderations

(i) Most of the increase in resistivity in the neighborhoodof the ldquocontrol pointrdquo occurs after the first injection

(ii) A decrease of resistivity is observed in the outershell of the displayed volume of soil we suggestthat this decrease can be related to water migratedthere due to the effect of resin expansion Watermigration is consistent with evidences coming fromgeotechnical data (see Section 7) which show that thesoil moisture conditions decrease significantly near

the resin veins as do the penetration resistance (pp)and the undrained cohesion (Cu) attest

(iii) The volume with the largest resistivity increase iscontained in a radius of about 1m around the injec-tion point with increases in resistivity sometimesclose to 100 for the given injected resin quantitiesand the site specific lithologies This is consistentwith visual information coming from the excavatedvolumes where it is possible to observe that at theinjection pressures where no preexisting weaknesschannels exist the channels of resin distribute them-selves and invade a surrounding volume of radiusapproximately 1m around the center of the injectionMoreover these volumes correspond to those wherethe improvement of the mechanical properties wasrecorded by the geotechnical tests described belowthis finding shows that increase in resistivity is due tothe reduction in the void ratio and compaction of thesoil


1m times 1m times 1m2m times 2m times 2m3m times 3m times 3m

IntermediateT0

30

35

40

45

50

55

60

T1 T2 T3

Aver

age r

esist

ivity

(Ohm

m)

Figure 6 Average of resistivities at different intermediates fordifferent volumes of soil around the control point

(iv) The T2 and T3 injections close to the ldquocontrol pointrdquoseem only to act in stabilizing the T1 resistivityscenario as if the nearest volume of soil did notundergo significant changes after the first injection

(v) An increase of resistivity is also observed in the threesurface blocks on the left side and a decrease in theremaining three on the right this behavior may beattributed to resilience of resin (Figure 7) due to thelack of load which in worksite conditions is given bythe building

(vi) The average of the resistivity of progressively increas-ing volumes at different intermediates tends to aconstant value larger volumes are less affected by theeffect of injections and probably the balancing effectof the resistivity decrease away from the injectionpoint due to fluids displacements contributes to thisresult Therefore as it is shown that the consolidatingaction of the resin injection is confined to the imme-diate approximately 1m neighbor of the injectionpoint spacing 1m the injection points in worksiteappears the proper choice

7 Geotechnical Investigations after Treatment

Thenew excavation down to a depth ofminus130 cm bgl (pit B inFigure 2) allowed to examine the volumes of soil affected bythe injections and directly observe the created resin networkadditionally it lets exposed a ground surface where it waspossible to carry out the same in situ tests as it was done inpit A (without treatment)

It is clearly highlighted how the preexisting open discon-tinuities or channels constitute the preferential escape path-ways for the distribution of the resins (Figure 7(a)) Howeverwhere none of these pathways is evident induced fracturing

systems can be spotted with characteristic directions Theconfiguration of the conduits sometimes centimetres widefilled by the hardened resin complies with the directions ofstress induced by the injections (Figure 7(b)) Furthermorea dendritic resin network is created which ldquostrengthensrdquothe adjoining soils (Figure 7(c)) Also the soil moistureconditions decrease significantly near these veins as dothe penetration resistance (pp) and the undrained cohesion(Cu) which measured along the distance between centresof two adjacent injections (1m) change respectively frompp cong 350 kPa with Cu cong 130 kPa to pp gt 441 kPa withCu gt 240 kPa (instrumental end scale values) Visually it ispossible to observe that at the injection pressures where nopreexisting weakness channels exist the channels of resindistribute themselves and invade a surrounding volume ofradius approximately 1 meter from the centre of the injectionDensity tests executed from the bottom of the pit nearby theinjection axis make it possible to obtain the weight volumeat natural moisture 120574

119900= 192 plusmn 08 kNm3 and the weight

volume in dry conditions 120574119889= 172 plusmn 11 kNm3 Although the

measurements depend on the entity of the resin ldquoimpregnat-ingrdquo the investigated volume it is observed that the overalldensity of the treated soil remains substantially unchangedor does not in any case represent a significant parameterin assessing the efficiency of the treatment This may beexplained considering that the density of the resin which hasfilled preexisting open fractures is lower than that of water

Even at the macroscale samples subjected to laboratorygeotechnical tests have different degrees of resin ldquoimpreg-nationrdquo resins may pass through the sample in veins orimpregnate it in a uniform manner samples subjected totests are distinct depending on the percentage of resin present(lt10 10ndash30 and gt30)

In Figure 8 the stress-strain behaviour revealed by meansof unconfined compression tests on nontreated and treatedsamples is comparedThe treated samples investigated have acompressive strength of 120590

119888= 1147 kPa (mean value taken from

9 samples) with 120590119888= 788ndash2136 kPa and average deformation

modulus 11986415 = 76MPa with 119864

15 = 492ndash1282MPa whichamounts to an increase of over 300 in the failure strengthvalues and approximately 250 in the elastic moduli

Also comparing the compressibility values obtainedthrough plate-bearing tests (Figure 9) executed at the bottomof the pit between two identical treatment injections it ispossible to appreciate a considerable increase in the bearingcapacity of the soil with 119872

119864= 285ndash386MPa and 1198721015840

119864=

476ndash587MPa calculated on the first and second load curvesrespectively The dotted line in Figure 9 delimits the field ofthe typical values of ldquopretreatmentrdquo (below) and ldquoposttreat-mentrdquo (above) soilThe data consistently reveal a certain scaleeffect the shaded area in Figure 9 groups the laboratory testsperformed on samples measuring 5 cm in diameter while theload plate has a diameter of 30 cm

The information provided by the CPTU tests carried outafter the injection (Figure 10) is compatible with the evidenceprovided by the excavation and the geotechnical parametersat the sample scale The CPTU tests show the achievedmechanical improvement around the treated area with


(a) (b)

(c)

Figure 7 Effects of resin treatment propagation of resins in clayey soils (a) main conduits along preexisting preferential weakness channels(b) induced fracturing and spreading on a horizontal plane (c) dendritic network at millimetric scale

ldquoPosttreatmentrdquo ldquoPretreatmentrdquo

2400

2000

1600

1200

800

400

00 1 2 3 4 5 6 7 8 9 10 11 12

Com

pres

sive s

tress

(kPa

)

Axial strain ()

Figure 8 Stress-strain curves from unconfined compression testsrefer to ldquopretreatmentrdquo samples and to ldquoposttreatmentrdquo samples

the mean increase values of cone resistance (119876119888) side friction

(119865119904) and friction ratio (119877

119891) indicated below

119876119888pre sim 7MPa

119876119888post sim 9MPa

119865119904pre sim 02MPa

119865119904post sim 05MPa

119877119891pre sim 25

119877119891post sim 45

(2)

Focusing on the intermediate layer high vales of 119876119888(up

to 16MPa) are locally reachedThe CPTU results are also coherent with the information

provided by the 3D ERTThe efficiency of the treatment and the suitability of

combing ETR monitoring and CPTU tests are confirmed bythe comparison of pre- and posttreatment distribution mapsof resistivity and cone resistance (119876

119888) Figure 11 overlays the

distribution of119876119888values before (a) and after (b) injections on

the horizontal section at the depth of 125 cm bgl which cor-responds to the shallowest minimum 119876

119888parameter with the

distribution of resistivity resulting from 3D resistivity modelConsidering the pretreatment results (Figure 11(a)) it can

be noted that the relative inhomogeneity of the resistivitydistribution ranges from values of 22Ohmsdotm to 42Ohmsdotmand at the same depth the contour distribution of 119876

119888val-

ues quite accurately reproduces the resistivity distributionThis good correlation between these selected geotechnicaland geophysical parameters is not surprising because bothparameters are strongly affected by grain size and compactionof loose sediments their concordant variations correspondto variations of soil facies from prevailing clay content


140

120

100

80

60

40

20

00

Test number1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Com

pres

sibili

ty an

d el

astic

ity m

odul

i (M

Pa)

0

500

1000

1500

2000

2500

Com

pres

sive s

treng

th120590c

(kPa

)ME pre

E pre

ME post

E post

M998400

M998400

E15 pre

E15 post120590c pre120590c post

Figure 9 Comparison of the ldquopretreatmentrdquo and ldquoposttreatmentrdquogeotechnical properties compressibility moduli119872

119864and1198721015840

119864(from

the first and second test cycle of plate-bearing test resp) elasticmoduli (119864

15) and unconfined compressive strength 120590119888

(smaller 119876119888and resistivity) to prevailing silt content (greater

119876119888and resistivity) Focusing on the posttreatments result

map (Figure 11(b)) the two distributions are consistent andcoherent A general increase of both parameters is wellevident the increment of cone resistance is followed by anincrease of resistivity The distribution patters seem to berelated to differences in the injection procedures (quantityand number of injections on the same vertical) in addition tothe original pretreatment not perfectly uniform distribution

8 Concluding Remarks

The experiments presented and discussed above were carriedout through a multidisciplinary approach which allowedrecording the ways in which the process of soil consolidationby injecting expanding resins occurs and modifies mechan-ical properties of injected soil volumes Volumes involvedand effectiveness of the treatment were evaluated in termsof increasing mechanical resistance and stiffness by meansof standard geotechnical tests Meanwhile the injectionsequence was monitored by successive 3D ERTmeasurementcycles which allowed observing a remarkable variation ofelectrical resistivity which in the present context is due towater movements In particular an increase of resistivity wasrecorded in treated volumes accompanying the improvementof their mechanical properties while a decrease of resistivitywas observed in surrounding volumes as the effect of theincrease in their content of water migrated from the injectedvolumes

Direct inspection through observations made along thewalls of the pit B has provided indications concerning thedistribution and spread of the injected resins and contributed

to support the 3D ERT as a noninvasive technique that isable to estimate the volumes involved in the process throughcompaction and migration of water held therein

Both in situ and laboratory geotechnical tests have shownhow the soils examined near the injected volumes signifi-cantly increase their bearing capacity strength and stiffnessIt is the authorsrsquo opinion that the contribution provided bythese injections is twofold on one hand it is linked to thereduction of the void ratio caused by the expansion of theresins and on the other by the presence of the resin itselfwhich compacts the treated soil in quite a uniform manner

The results highlight the potential of integration betweengeotechnical analyses and geophysical surveys in defininga geotechnical-geophysical procedure to be applied bothin the design and in the operative phases for assessing theconsolidation in progress

The discussion above allows confirming that the pro-cedure followed in the test and already used in worksites[6 7] carries to a possible ldquobest practicerdquo for the describedprocedure of planning and monitoring the consolidation ofsettled foundations by means of resin injections that candetailed as follows

(1) A 3DERT survey is carried out in advance in order toestablish the initial conditions of the soil to be consol-idatedThe 3D representation of subsurface resistivitydistribution associatedwith the information derivingfrom the geotechnical survey (penetrometric or othertests) allows an initial general classification of thesoils The effectiveness of combining these surveytechniques was recently confirmed by Dahlin et al[26] Moreover the ERT provides details regardingthe type continuity and depth of the foundationcharacterising any anomalies due to the presence ofvoids water retention or other distinctive lithologicalelements

(2) The preliminary geophysical information is inte-grated with the geotechnical and structural data avail-able (crack pattern geometry of the foundations andloads) and contributes to the detailed design of thetreatment procedure in terms of location numberdepth of the injection holes and quantities of resinto be injected

(3) In the course of the injection procedure intermediateERT surveys carried out using the same electrodearray designed in phase 1 are conducted with the aimof investigating the status of the treatment of the soilvolumes affected by the displacement and the varia-tions in the fluid content in the subsurface making itpossible to redesign the treatment practically in realtime on the basis of the emerging worksite evidence

(4) Just after completion of the procedure a final 3DERT verifies the new subsurface conditions after theconsolidation procedure In all steps electrodes ofthe measuring layout must be kept fixed to ensurerepeatability of results



Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

0 2 4 6 8 10 12 14 16

minus24

minus28


Qc max (MPa)

0 2 4 6 8 10 12

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28


Rf max ()


Figure 10 Cumulative results of CPTU geotechnical tests performed after injections cone penetration resistance 119876119888 friction ratio 119877

119891

x (m)

y(m

)

CPTU9CPTU7

CPTU4

CPTU8

CPTU5

CPTU1

CPTU3

CPTU2

CPTU6

20

51

53

54

5453 52

56

58

61

61

59

63

5656

5861 53

57

59

61

63

65

63

66

20

25

30

35

40

45

50

55

60

25 30 35 40 45 50 55 60

48

44

40

36

32

28

24

20

Resis

tivity

(Ohm

m)

(a)

Resis

tivity

(Ohm

m)

x (m)

y(m

)

20

20

25

30

35

40

45

50

55

60

25 30 35

118

40 45 50 55 60

CPTU9 CPTU3

CPTU6CPTU1CPTU8

CPTU4 CPTU5

CPTU7110105

98

8885

82

80

92

48

44

40

36

32

28

24

20

82 80

78

75

72

85

90

82

105 75

78

80

82

85927

5

(b)

Figure 11 Comparison between pre- (a) and posttreatment (b) test results horizontal section of the 3D resistivity model at 125 cm bgl and119876119888contour lines (black lines) by interpolation at the same depth of all CPTU tests


Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

The authors wish to thank Marco Perfido technician of theEngineering Geology Laboratory for Testing Material of theDepartment of Earth Science University of Milan

References

[1] M Vincent ldquoProjet ARGIC Analyse du Retrait-Gonflementet de ses Incidences sur les Constructionsrdquo Projet ANR-05-PRGCU-005 Rapport Final Rapport BRGMRP-57011 2009(French)

[2] M Favaretti G Germanino A Pasquetto and G VincoldquoInterventi di consolidamento dei terreni di fondazione diuna torre campanaria con iniezioni di resina ad alta pressionedrsquoespansionerdquo in Proceedings of the XXII Convegno Nazionale diGeotecnica pp 1ndash19 AssociazioneGeotecnica Italiana PalermoItaly September 2004

[3] M Gabassi A Pasquetto G Vinco and F Mansueto ldquo3DFEM analysis of soil improving resin injections underneath amediaeval tower in Italyrdquo in Proceedings of the 7th EuropeanConference on Numerical Methods in Geotechnical Engineeringpp 827ndash832 2010

[4] O Buzzi S Fityus Y Sasaki and S Sloan ldquoStructure and prop-erties of expanding polyurethane foam in the context of foun-dation remediation in expansive soilrdquo Mechanics of Materialsvol 40 no 12 pp 1012ndash1021 2008

[5] O Buzzi S Fityus and S W Sloan ldquoUse of expandingpolyurethane resin to remediate expansive soil foundationsrdquoCanadian Geotechnical Journal vol 47 no 6 pp 623ndash634 2010

[6] G Santarato G Ranieri M Occhi G Morelli F Fischangerand D Gualerzi ldquoThree-Dimensional Electrical ResistivityTomography to control the injection of expanding resins forthe treatment and stabilization of foundation soilsrdquo EngineeringGeology vol 119 no 1-2 pp 18ndash30 2011

[7] F Fischanger G Morelli G Ranieri G Santarato and MOcchi ldquo4D cross-borehole electrical resistivity tomography tocontrol resin injection for ground stabilization a case history inVenice (Italy)rdquo Near Surface Geophysics vol 11 no 1 pp 41ndash502013

[8] A Dei Svaldi M Favaretti A Pasquetto and G Vinco ldquoAna-lytical modelling of the soil improvement by injections of highexpansion pressure resinrdquo Bulletin fur Angewandte Geologievol 10 no 2 pp 71ndash81 2005

[9] European Patent Specification ldquoA method for homogenizingand stabilising a soil by way of injectionsrdquo EP 1914350 2011

[10] Istituto Superiore per la Protezione e la Ricerca Ambientale(ISPRA) Carta Geologica drsquoItalia alla Scala 150000 Foglio 199Parma SUD Servizio Geologico drsquoItalia 2013 httpwwwis-prambientegovitMediacarg199 PARMA SUDFogliohtml

[11] Q Y Zhou J Shimada and A Sato ldquoThree-dimensional spatialand temporal monitoring of soil water content using electricalresistivity tomographyrdquoWater Resources Research vol 37 no 2pp 273ndash285 2001

[12] A Samouelian I Cousin A Tabbagh A Bruand and GRichard ldquoElectrical resistivity survey in soil science a reviewrdquoSoil and Tillage Research vol 83 no 2 pp 173ndash193 2005

[13] P Brunet R Clement and C Bouvier ldquoMonitoring soil watercontent and deficit using Electrical Resistivity Tomography(ERT)mdasha case study in the Cevennes area Francerdquo Journal ofHydrology vol 380 no 1-2 pp 146ndash153 2010

[14] M Chretien J F Lataste R Fabre and A Denis ldquoElectricalresistivity tomography to understand clay behavior duringseasonalwater content variationsrdquoEngineeringGeology vol 169pp 112ndash123 2014

[15] R D Barker ldquoThe offset system of electrical resistivity soundingand its use with a multicore cablerdquo Geophysical Prospecting vol29 no 1 pp 128ndash143 1981

[16] G Morelli and D J LaBrecque ldquoAdvances in ERT inversemodelingrdquo European Journal of Environmental and EngineeringGeophysics vol 1 no 2 pp 171ndash186 1996

[17] ASTM (American Society for Testing and Materials) AnnualBook of ASTM Standards Soil and Rock Building StonesGeotextiles vol 0408 D 2487 1987

[18] ASTM D1556-07 Standard Test Method for Density and UnitWeight of Soil in Place by the Sand-Cone Method 2007

[19] ASTMInternationalASTMD2167-08 StandardTestMethod forDensity and Unit Weight of Soil in Place by the Rubber BalloonMethod ASTM International West Conshohocken Pa USA2008

[20] ASTM InternationalASTMD2937-10 Standard TestMethod forDensity of Soil in Place by the Drive-Cylinder Method ASTMInternational West Conshohocken Pa USA 2010

[21] J H Schoen Physical Properties of Rocks 18 Fundamentals andPrinciples of Petrophysics Pergamon Press 2004

[22] ASTM D3080-04 Standard Test Method for Direct Shear Testof Soils Under Consolidated Drained Conditions

[23] T Apuani G P Beretta and R Pellegrini Linee Guida perLrsquoinertizzazione In Situ dei Suoli Contaminati vol 12 Provinciadi Milano 2006 (Italian)

[24] CNR ldquoDeterminazione dei moduli di deformazione Md e Mdrsquomediante prova di carico a doppio ciclo con piastra circolarerdquoBollettino Ufficiale (Norme tecniche) vol 26 no 146 1992(Italian) in Italian

[25] Y Sasaki ldquoTwo-dimensional joint inversion of magnetotelluricand dipole-dipole resistivity datardquoGeophysics vol 54 no 2 pp254ndash262 1989

[26] TDahlinH Lofroth D Schalin and P Suer ldquoMapping of quickclay using geoelectrical imaging and CPTU-resistivityrdquo NearSurface Geophysics vol 11 no 6 pp 659ndash670 2013

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Active and Passive Electronic Components

Control Scienceand Engineering

Journal of



RotatingMachinery


Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design



Shock and Vibration


Civil EngineeringAdvances in

Acoustics and VibrationAdvances in



Electrical and Computer Engineering

Journal of

Advances inOptoElectronics


Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of


Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014


Chemical EngineeringInternational Journal of Antennas and

Propagation




Navigation and Observation



DistributedSensor Networks



AES8AES8AES3

AES7a

b1

AES8a

595771

595771

596771

596771

597771

597771

598771

598771

599771

599771

600771

600771 4955

029

4956

029

4957

029

4958

029

ParmaTest site

AostaTrento

Genova

TorinoMilano

TriesteVenezia

Bologna

Firenze

AES3-Agazzano SubsynthemAES7a-Niviano unitAES8-Ravenna Subsynthem

AES8a-Modena unitb1-Alluvial sedimentsTest site

(a)

(b)

(c)

N0 500 1000250

(m)

Ancona

Figure 1 (a) Test site location in Italy (b) Geological map of the area (ISPRA Sheet 199 coordinates are in meters ED50) (c) View of thetest site

applied loads The interaction between water and foundationsoil is undoubtedly one of the most important mechanismsand a critical factor for all types of ground Clayey soils infact have the capacity to absorb large quantities of waterwhich leads to a considerable increase in volume On theother hand loss of water manifests itself in a decrease in thevolume of the ground If periods of heavy rain alternate withperiods of drought the volume of the ground is cyclically sub-jected to swelling and shrinkage [1] which leads to the cre-ation of voids hence to the risk of differential displacementGranular soils in contrast exhibit greater permeability andthewater circulates freely possibly transporting fine particlesThis circulation if sufficiently intense can progressively leadto the creation of voids and cavities which often contributeto the phenomenon of foundation settlements

Many factors affect the process of soil consolidation byinjections of expanding resins on one side the geotechnicaland hydrogeological context and on the other the specificresin-based consolidation technique Although the use ofresin-based consolidation techniques is more and moregrowing the full comprehension of the process involved isnot completely achieved yet Some authors have presentedcase studies in different geological contexts using specificresin and injection techniques [2 3] Some studies aredevoted to explore the variation of geotechnical hydrogeo-logical and geophysical properties of soils during and afterthe treatment by a back analysis approach on dedicated testsites [4 5] or real application cases [6 7] Only few authorshave applied a theoretical approach to predict the treatment

efficiency [8] It results that the topic needs to be scientificallyinvestigated further

Due to the complexity of the system (soilresin) it isunavoidable that each study is dependent on the geotechnicalcontext as well as on the product and procedure used To shedlight on the observed correlation between geotechnical andgeoelectrical response variations due to resin injection thatallow to use time-lapse resistivity surveys to suitably monitorthe injection process a full-scale field test was planned Hereinjections of two-component polyurethane expanding resinwere executed following the procedure already described bySantarato et al ([6] see also [9]) Detailed geotechnical testswere performed before during and after the injections andrepeated three-dimensional electrical resistivity tomography(3D-ERT) was performed as well

The test site was purposely selected to analysewhat occursin recovery of foundation settlements by means of resininjection in cohesive soils which is a very frequent althoughspecific occurrence in the consolidation practice

2 The Test Site Geological Outline

A full-scale test site was set up where resin injections werecarried out in compliance with the usual procedure followedin real cases of settlements of building foundations

The test site is an agricultural field presently uncultivatedlocated south-west of Parma in the Municipality of Collec-chio (Figures 1(a) and 1(c)) From the geological point of viewit lies in the foredeep of the Apennine chain which rises to








nabla2119881 = 0 (1)









V1

V2

V3

V4

D1

Cp1

Cp2

Cp3

F1-5

Ci2pre

Ci3pre

Ci1pre


Cp4Ds1

Ci3post

Ci1post

Ci2post

T1

T2 Cp7

Cp5

GDs2

B

F

A

C D E

(a) (c)

(d)

(e)


Cp6

460m

630

m

60

m

CPTU

3D electrodes


InjectionsSingle

Double





















119889= 161 plusmn





119888)


2) parameters Both





2among tests is not






ratio (119877119891)





119888









119864=








Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

0 0

0 10 20 30 40 50 60 70 80 90

2 4 6 8 10 122 4 6 8 10 12 14 16

minus24

minus28

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28


Qc max (MPa)



u2 max (kPa)


Rf max ()


(a)

108

64

2

80

72

64

56

48

40

32

24

YX

Z

1416

12

0

0

6

8

42

minus4

minus1

minus3minus2

Resis

tivity

(Ohm

m)

(b)


119891



Cl1PRE

E44 E43 E42 E41

F9 F9b

F7 F7b

F5 F6F8 F8b

Ci6POST

CPTU6

24kg

24kg

25kg a minus150m

25kg a minus150m

25kg a minus150m

E38

E40

E39

+25kg a minus250m

+25kg a minus250m

+25kg a minus250m

aminus150

m

aminus150

m

(a)

minus150

minus300

001830

1840

1850

1860

1865

300

150

0000X

Y

Z

1855

1845

1835

360

365

370

375

380

385

Res diff ()

minus20

minus15

minus10

minus05

(b)













Injection

ElectrodesInjection


F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

Displayed section

80

65

50

35

0

15

30

20

minus15

minus30




343 (a) 371 (b) 426 (c) 568 (a) 466 (b) 458 (c) 577 (a) 469 (b) 450 (c) 571(a) 468 (b) 455 (c)

Res diff()

05m

1m2m

3m





(Ohm m)Res












IntermediateT0

30

35

40

45

50

55

60

T1 T2 T3

Aver

age r

esist

ivity

(Ohm

m)
















modulus 11986415 = 76MPa with 119864



119864= 285ndash386MPa and 1198721015840

119864=




(a) (b)

(c)



2400

2000

1600

1200

800

400

00 1 2 3 4 5 6 7 8 9 10 11 12

Com

pres

sive s

tress

(kPa

)

Axial strain ()





119876119888pre sim 7MPa


119865119904pre sim 02MPa

119865119904post sim 05MPa

119877119891pre sim 25

119877119891post sim 45

(2)











119888val-



140

120

100

80

60

40

20

00

Test number1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Com

pres

sibili

ty an

d el

astic

ity m

odul

i (M

Pa)

0

500

1000

1500

2000

2500

Com

pres

sive s

treng

th120590c

(kPa

)ME pre

E pre

ME post

E post

M998400

M998400

E15 pre



119864and1198721015840

119864(from



















Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

0 2 4 6 8 10 12 14 16

minus24

minus28


Qc max (MPa)

0 2 4 6 8 10 12

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28


Rf max ()



119891

x (m)

y(m

)

CPTU9CPTU7

CPTU4

CPTU8

CPTU5

CPTU1

CPTU3

CPTU2

CPTU6

20

51

53

54

5453 52

56

58

61

61

59

63

5656

5861 53

57

59

61

63

65

63

66

20

25

30

35

40

45

50

55

60

25 30 35 40 45 50 55 60

48

44

40

36

32

28

24

20

Resis

tivity

(Ohm

m)

(a)

Resis

tivity

(Ohm

m)

x (m)

y(m

)

20

20

25

30

35

40

45

50

55

60

25 30 35

118

40 45 50 55 60

CPTU9 CPTU3

CPTU6CPTU1CPTU8

CPTU4 CPTU5

CPTU7110105

98

8885

82

80

92

48

44

40

36

32

28

24

20

82 80

78

75

72

85

90

82

105 75

78

80

82

85927

5

(b)





Acknowledgment


References





























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation
















nabla2119881 = 0 (1)









V1

V2

V3

V4

D1

Cp1

Cp2

Cp3

F1-5

Ci2pre

Ci3pre

Ci1pre


Cp4Ds1

Ci3post

Ci1post

Ci2post

T1

T2 Cp7

Cp5

GDs2

B

F

A

C D E

(a) (c)

(d)

(e)


Cp6

460m

630

m

60

m

CPTU

3D electrodes


InjectionsSingle

Double





















119889= 161 plusmn





119888)


2) parameters Both





2among tests is not






ratio (119877119891)





119888









119864=








Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

0 0

0 10 20 30 40 50 60 70 80 90

2 4 6 8 10 122 4 6 8 10 12 14 16

minus24

minus28

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28


Qc max (MPa)



u2 max (kPa)


Rf max ()


(a)

108

64

2

80

72

64

56

48

40

32

24

YX

Z

1416

12

0

0

6

8

42

minus4

minus1

minus3minus2

Resis

tivity

(Ohm

m)

(b)


119891



Cl1PRE

E44 E43 E42 E41

F9 F9b

F7 F7b

F5 F6F8 F8b

Ci6POST

CPTU6

24kg

24kg

25kg a minus150m

25kg a minus150m

25kg a minus150m

E38

E40

E39

+25kg a minus250m

+25kg a minus250m

+25kg a minus250m

aminus150

m

aminus150

m

(a)

minus150

minus300

001830

1840

1850

1860

1865

300

150

0000X

Y

Z

1855

1845

1835

360

365

370

375

380

385

Res diff ()

minus20

minus15

minus10

minus05

(b)













Injection

ElectrodesInjection


F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

Displayed section

80

65

50

35

0

15

30

20

minus15

minus30




343 (a) 371 (b) 426 (c) 568 (a) 466 (b) 458 (c) 577 (a) 469 (b) 450 (c) 571(a) 468 (b) 455 (c)

Res diff()

05m

1m2m

3m





(Ohm m)Res












IntermediateT0

30

35

40

45

50

55

60

T1 T2 T3

Aver

age r

esist

ivity

(Ohm

m)
















modulus 11986415 = 76MPa with 119864



119864= 285ndash386MPa and 1198721015840

119864=




(a) (b)

(c)



2400

2000

1600

1200

800

400

00 1 2 3 4 5 6 7 8 9 10 11 12

Com

pres

sive s

tress

(kPa

)

Axial strain ()





119876119888pre sim 7MPa


119865119904pre sim 02MPa

119865119904post sim 05MPa

119877119891pre sim 25

119877119891post sim 45

(2)











119888val-



140

120

100

80

60

40

20

00

Test number1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Com

pres

sibili

ty an

d el

astic

ity m

odul

i (M

Pa)

0

500

1000

1500

2000

2500

Com

pres

sive s

treng

th120590c

(kPa

)ME pre

E pre

ME post

E post

M998400

M998400

E15 pre



119864and1198721015840

119864(from



















Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

0 2 4 6 8 10 12 14 16

minus24

minus28


Qc max (MPa)

0 2 4 6 8 10 12

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28


Rf max ()



119891

x (m)

y(m

)

CPTU9CPTU7

CPTU4

CPTU8

CPTU5

CPTU1

CPTU3

CPTU2

CPTU6

20

51

53

54

5453 52

56

58

61

61

59

63

5656

5861 53

57

59

61

63

65

63

66

20

25

30

35

40

45

50

55

60

25 30 35 40 45 50 55 60

48

44

40

36

32

28

24

20

Resis

tivity

(Ohm

m)

(a)

Resis

tivity

(Ohm

m)

x (m)

y(m

)

20

20

25

30

35

40

45

50

55

60

25 30 35

118

40 45 50 55 60

CPTU9 CPTU3

CPTU6CPTU1CPTU8

CPTU4 CPTU5

CPTU7110105

98

8885

82

80

92

48

44

40

36

32

28

24

20

82 80

78

75

72

85

90

82

105 75

78

80

82

85927

5

(b)





Acknowledgment


References





























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










V1

V2

V3

V4

D1

Cp1

Cp2

Cp3

F1-5

Ci2pre

Ci3pre

Ci1pre


Cp4Ds1

Ci3post

Ci1post

Ci2post

T1

T2 Cp7

Cp5

GDs2

B

F

A

C D E

(a) (c)

(d)

(e)


Cp6

460m

630

m

60

m

CPTU

3D electrodes


InjectionsSingle

Double





















119889= 161 plusmn





119888)


2) parameters Both





2among tests is not






ratio (119877119891)





119888









119864=








Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

0 0

0 10 20 30 40 50 60 70 80 90

2 4 6 8 10 122 4 6 8 10 12 14 16

minus24

minus28

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28


Qc max (MPa)



u2 max (kPa)


Rf max ()


(a)

108

64

2

80

72

64

56

48

40

32

24

YX

Z

1416

12

0

0

6

8

42

minus4

minus1

minus3minus2

Resis

tivity

(Ohm

m)

(b)


119891



Cl1PRE

E44 E43 E42 E41

F9 F9b

F7 F7b

F5 F6F8 F8b

Ci6POST

CPTU6

24kg

24kg

25kg a minus150m

25kg a minus150m

25kg a minus150m

E38

E40

E39

+25kg a minus250m

+25kg a minus250m

+25kg a minus250m

aminus150

m

aminus150

m

(a)

minus150

minus300

001830

1840

1850

1860

1865

300

150

0000X

Y

Z

1855

1845

1835

360

365

370

375

380

385

Res diff ()

minus20

minus15

minus10

minus05

(b)













Injection

ElectrodesInjection


F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

Displayed section

80

65

50

35

0

15

30

20

minus15

minus30




343 (a) 371 (b) 426 (c) 568 (a) 466 (b) 458 (c) 577 (a) 469 (b) 450 (c) 571(a) 468 (b) 455 (c)

Res diff()

05m

1m2m

3m





(Ohm m)Res












IntermediateT0

30

35

40

45

50

55

60

T1 T2 T3

Aver

age r

esist

ivity

(Ohm

m)
















modulus 11986415 = 76MPa with 119864



119864= 285ndash386MPa and 1198721015840

119864=




(a) (b)

(c)



2400

2000

1600

1200

800

400

00 1 2 3 4 5 6 7 8 9 10 11 12

Com

pres

sive s

tress

(kPa

)

Axial strain ()





119876119888pre sim 7MPa


119865119904pre sim 02MPa

119865119904post sim 05MPa

119877119891pre sim 25

119877119891post sim 45

(2)











119888val-



140

120

100

80

60

40

20

00

Test number1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Com

pres

sibili

ty an

d el

astic

ity m

odul

i (M

Pa)

0

500

1000

1500

2000

2500

Com

pres

sive s

treng

th120590c

(kPa

)ME pre

E pre

ME post

E post

M998400

M998400

E15 pre



119864and1198721015840

119864(from



















Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

0 2 4 6 8 10 12 14 16

minus24

minus28


Qc max (MPa)

0 2 4 6 8 10 12

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28


Rf max ()



119891

x (m)

y(m

)

CPTU9CPTU7

CPTU4

CPTU8

CPTU5

CPTU1

CPTU3

CPTU2

CPTU6

20

51

53

54

5453 52

56

58

61

61

59

63

5656

5861 53

57

59

61

63

65

63

66

20

25

30

35

40

45

50

55

60

25 30 35 40 45 50 55 60

48

44

40

36

32

28

24

20

Resis

tivity

(Ohm

m)

(a)

Resis

tivity

(Ohm

m)

x (m)

y(m

)

20

20

25

30

35

40

45

50

55

60

25 30 35

118

40 45 50 55 60

CPTU9 CPTU3

CPTU6CPTU1CPTU8

CPTU4 CPTU5

CPTU7110105

98

8885

82

80

92

48

44

40

36

32

28

24

20

82 80

78

75

72

85

90

82

105 75

78

80

82

85927

5

(b)





Acknowledgment


References





























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation












119889= 161 plusmn





119888)


2) parameters Both





2among tests is not






ratio (119877119891)





119888









119864=








Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

0 0

0 10 20 30 40 50 60 70 80 90

2 4 6 8 10 122 4 6 8 10 12 14 16

minus24

minus28

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28


Qc max (MPa)



u2 max (kPa)


Rf max ()


(a)

108

64

2

80

72

64

56

48

40

32

24

YX

Z

1416

12

0

0

6

8

42

minus4

minus1

minus3minus2

Resis

tivity

(Ohm

m)

(b)


119891



Cl1PRE

E44 E43 E42 E41

F9 F9b

F7 F7b

F5 F6F8 F8b

Ci6POST

CPTU6

24kg

24kg

25kg a minus150m

25kg a minus150m

25kg a minus150m

E38

E40

E39

+25kg a minus250m

+25kg a minus250m

+25kg a minus250m

aminus150

m

aminus150

m

(a)

minus150

minus300

001830

1840

1850

1860

1865

300

150

0000X

Y

Z

1855

1845

1835

360

365

370

375

380

385

Res diff ()

minus20

minus15

minus10

minus05

(b)













Injection

ElectrodesInjection


F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

Displayed section

80

65

50

35

0

15

30

20

minus15

minus30




343 (a) 371 (b) 426 (c) 568 (a) 466 (b) 458 (c) 577 (a) 469 (b) 450 (c) 571(a) 468 (b) 455 (c)

Res diff()

05m

1m2m

3m





(Ohm m)Res












IntermediateT0

30

35

40

45

50

55

60

T1 T2 T3

Aver

age r

esist

ivity

(Ohm

m)
















modulus 11986415 = 76MPa with 119864



119864= 285ndash386MPa and 1198721015840

119864=




(a) (b)

(c)



2400

2000

1600

1200

800

400

00 1 2 3 4 5 6 7 8 9 10 11 12

Com

pres

sive s

tress

(kPa

)

Axial strain ()





119876119888pre sim 7MPa


119865119904pre sim 02MPa

119865119904post sim 05MPa

119877119891pre sim 25

119877119891post sim 45

(2)











119888val-



140

120

100

80

60

40

20

00

Test number1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Com

pres

sibili

ty an

d el

astic

ity m

odul

i (M

Pa)

0

500

1000

1500

2000

2500

Com

pres

sive s

treng

th120590c

(kPa

)ME pre

E pre

ME post

E post

M998400

M998400

E15 pre



119864and1198721015840

119864(from



















Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

0 2 4 6 8 10 12 14 16

minus24

minus28


Qc max (MPa)

0 2 4 6 8 10 12

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28


Rf max ()



119891

x (m)

y(m

)

CPTU9CPTU7

CPTU4

CPTU8

CPTU5

CPTU1

CPTU3

CPTU2

CPTU6

20

51

53

54

5453 52

56

58

61

61

59

63

5656

5861 53

57

59

61

63

65

63

66

20

25

30

35

40

45

50

55

60

25 30 35 40 45 50 55 60

48

44

40

36

32

28

24

20

Resis

tivity

(Ohm

m)

(a)

Resis

tivity

(Ohm

m)

x (m)

y(m

)

20

20

25

30

35

40

45

50

55

60

25 30 35

118

40 45 50 55 60

CPTU9 CPTU3

CPTU6CPTU1CPTU8

CPTU4 CPTU5

CPTU7110105

98

8885

82

80

92

48

44

40

36

32

28

24

20

82 80

78

75

72

85

90

82

105 75

78

80

82

85927

5

(b)





Acknowledgment


References





























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

0 0

0 10 20 30 40 50 60 70 80 90

2 4 6 8 10 122 4 6 8 10 12 14 16

minus24

minus28

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28


Qc max (MPa)



u2 max (kPa)


Rf max ()


(a)

108

64

2

80

72

64

56

48

40

32

24

YX

Z

1416

12

0

0

6

8

42

minus4

minus1

minus3minus2

Resis

tivity

(Ohm

m)

(b)


119891



Cl1PRE

E44 E43 E42 E41

F9 F9b

F7 F7b

F5 F6F8 F8b

Ci6POST

CPTU6

24kg

24kg

25kg a minus150m

25kg a minus150m

25kg a minus150m

E38

E40

E39

+25kg a minus250m

+25kg a minus250m

+25kg a minus250m

aminus150

m

aminus150

m

(a)

minus150

minus300

001830

1840

1850

1860

1865

300

150

0000X

Y

Z

1855

1845

1835

360

365

370

375

380

385

Res diff ()

minus20

minus15

minus10

minus05

(b)













Injection

ElectrodesInjection


F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

Displayed section

80

65

50

35

0

15

30

20

minus15

minus30




343 (a) 371 (b) 426 (c) 568 (a) 466 (b) 458 (c) 577 (a) 469 (b) 450 (c) 571(a) 468 (b) 455 (c)

Res diff()

05m

1m2m

3m





(Ohm m)Res












IntermediateT0

30

35

40

45

50

55

60

T1 T2 T3

Aver

age r

esist

ivity

(Ohm

m)
















modulus 11986415 = 76MPa with 119864



119864= 285ndash386MPa and 1198721015840

119864=




(a) (b)

(c)



2400

2000

1600

1200

800

400

00 1 2 3 4 5 6 7 8 9 10 11 12

Com

pres

sive s

tress

(kPa

)

Axial strain ()





119876119888pre sim 7MPa


119865119904pre sim 02MPa

119865119904post sim 05MPa

119877119891pre sim 25

119877119891post sim 45

(2)











119888val-



140

120

100

80

60

40

20

00

Test number1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Com

pres

sibili

ty an

d el

astic

ity m

odul

i (M

Pa)

0

500

1000

1500

2000

2500

Com

pres

sive s

treng

th120590c

(kPa

)ME pre

E pre

ME post

E post

M998400

M998400

E15 pre



119864and1198721015840

119864(from



















Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

0 2 4 6 8 10 12 14 16

minus24

minus28


Qc max (MPa)

0 2 4 6 8 10 12

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28


Rf max ()



119891

x (m)

y(m

)

CPTU9CPTU7

CPTU4

CPTU8

CPTU5

CPTU1

CPTU3

CPTU2

CPTU6

20

51

53

54

5453 52

56

58

61

61

59

63

5656

5861 53

57

59

61

63

65

63

66

20

25

30

35

40

45

50

55

60

25 30 35 40 45 50 55 60

48

44

40

36

32

28

24

20

Resis

tivity

(Ohm

m)

(a)

Resis

tivity

(Ohm

m)

x (m)

y(m

)

20

20

25

30

35

40

45

50

55

60

25 30 35

118

40 45 50 55 60

CPTU9 CPTU3

CPTU6CPTU1CPTU8

CPTU4 CPTU5

CPTU7110105

98

8885

82

80

92

48

44

40

36

32

28

24

20

82 80

78

75

72

85

90

82

105 75

78

80

82

85927

5

(b)





Acknowledgment


References





























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










Cl1PRE

E44 E43 E42 E41

F9 F9b

F7 F7b

F5 F6F8 F8b

Ci6POST

CPTU6

24kg

24kg

25kg a minus150m

25kg a minus150m

25kg a minus150m

E38

E40

E39

+25kg a minus250m

+25kg a minus250m

+25kg a minus250m

aminus150

m

aminus150

m

(a)

minus150

minus300

001830

1840

1850

1860

1865

300

150

0000X

Y

Z

1855

1845

1835

360

365

370

375

380

385

Res diff ()

minus20

minus15

minus10

minus05

(b)













Injection

ElectrodesInjection


F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

Displayed section

80

65

50

35

0

15

30

20

minus15

minus30




343 (a) 371 (b) 426 (c) 568 (a) 466 (b) 458 (c) 577 (a) 469 (b) 450 (c) 571(a) 468 (b) 455 (c)

Res diff()

05m

1m2m

3m





(Ohm m)Res












IntermediateT0

30

35

40

45

50

55

60

T1 T2 T3

Aver

age r

esist

ivity

(Ohm

m)
















modulus 11986415 = 76MPa with 119864



119864= 285ndash386MPa and 1198721015840

119864=




(a) (b)

(c)



2400

2000

1600

1200

800

400

00 1 2 3 4 5 6 7 8 9 10 11 12

Com

pres

sive s

tress

(kPa

)

Axial strain ()





119876119888pre sim 7MPa


119865119904pre sim 02MPa

119865119904post sim 05MPa

119877119891pre sim 25

119877119891post sim 45

(2)











119888val-



140

120

100

80

60

40

20

00

Test number1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Com

pres

sibili

ty an

d el

astic

ity m

odul

i (M

Pa)

0

500

1000

1500

2000

2500

Com

pres

sive s

treng

th120590c

(kPa

)ME pre

E pre

ME post

E post

M998400

M998400

E15 pre



119864and1198721015840

119864(from



















Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

0 2 4 6 8 10 12 14 16

minus24

minus28


Qc max (MPa)

0 2 4 6 8 10 12

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28


Rf max ()



119891

x (m)

y(m

)

CPTU9CPTU7

CPTU4

CPTU8

CPTU5

CPTU1

CPTU3

CPTU2

CPTU6

20

51

53

54

5453 52

56

58

61

61

59

63

5656

5861 53

57

59

61

63

65

63

66

20

25

30

35

40

45

50

55

60

25 30 35 40 45 50 55 60

48

44

40

36

32

28

24

20

Resis

tivity

(Ohm

m)

(a)

Resis

tivity

(Ohm

m)

x (m)

y(m

)

20

20

25

30

35

40

45

50

55

60

25 30 35

118

40 45 50 55 60

CPTU9 CPTU3

CPTU6CPTU1CPTU8

CPTU4 CPTU5

CPTU7110105

98

8885

82

80

92

48

44

40

36

32

28

24

20

82 80

78

75

72

85

90

82

105 75

78

80

82

85927

5

(b)





Acknowledgment


References





























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










Injection

ElectrodesInjection


F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

F5 F6 F7 F7b

F9 F9b

F8 F8b

Displayed section

80

65

50

35

0

15

30

20

minus15

minus30




343 (a) 371 (b) 426 (c) 568 (a) 466 (b) 458 (c) 577 (a) 469 (b) 450 (c) 571(a) 468 (b) 455 (c)

Res diff()

05m

1m2m

3m





(Ohm m)Res












IntermediateT0

30

35

40

45

50

55

60

T1 T2 T3

Aver

age r

esist

ivity

(Ohm

m)
















modulus 11986415 = 76MPa with 119864



119864= 285ndash386MPa and 1198721015840

119864=




(a) (b)

(c)



2400

2000

1600

1200

800

400

00 1 2 3 4 5 6 7 8 9 10 11 12

Com

pres

sive s

tress

(kPa

)

Axial strain ()





119876119888pre sim 7MPa


119865119904pre sim 02MPa

119865119904post sim 05MPa

119877119891pre sim 25

119877119891post sim 45

(2)











119888val-



140

120

100

80

60

40

20

00

Test number1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Com

pres

sibili

ty an

d el

astic

ity m

odul

i (M

Pa)

0

500

1000

1500

2000

2500

Com

pres

sive s

treng

th120590c

(kPa

)ME pre

E pre

ME post

E post

M998400

M998400

E15 pre



119864and1198721015840

119864(from



















Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

0 2 4 6 8 10 12 14 16

minus24

minus28


Qc max (MPa)

0 2 4 6 8 10 12

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28


Rf max ()



119891

x (m)

y(m

)

CPTU9CPTU7

CPTU4

CPTU8

CPTU5

CPTU1

CPTU3

CPTU2

CPTU6

20

51

53

54

5453 52

56

58

61

61

59

63

5656

5861 53

57

59

61

63

65

63

66

20

25

30

35

40

45

50

55

60

25 30 35 40 45 50 55 60

48

44

40

36

32

28

24

20

Resis

tivity

(Ohm

m)

(a)

Resis

tivity

(Ohm

m)

x (m)

y(m

)

20

20

25

30

35

40

45

50

55

60

25 30 35

118

40 45 50 55 60

CPTU9 CPTU3

CPTU6CPTU1CPTU8

CPTU4 CPTU5

CPTU7110105

98

8885

82

80

92

48

44

40

36

32

28

24

20

82 80

78

75

72

85

90

82

105 75

78

80

82

85927

5

(b)





Acknowledgment


References





























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











IntermediateT0

30

35

40

45

50

55

60

T1 T2 T3

Aver

age r

esist

ivity

(Ohm

m)
















modulus 11986415 = 76MPa with 119864



119864= 285ndash386MPa and 1198721015840

119864=




(a) (b)

(c)



2400

2000

1600

1200

800

400

00 1 2 3 4 5 6 7 8 9 10 11 12

Com

pres

sive s

tress

(kPa

)

Axial strain ()





119876119888pre sim 7MPa


119865119904pre sim 02MPa

119865119904post sim 05MPa

119877119891pre sim 25

119877119891post sim 45

(2)











119888val-



140

120

100

80

60

40

20

00

Test number1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Com

pres

sibili

ty an

d el

astic

ity m

odul

i (M

Pa)

0

500

1000

1500

2000

2500

Com

pres

sive s

treng

th120590c

(kPa

)ME pre

E pre

ME post

E post

M998400

M998400

E15 pre



119864and1198721015840

119864(from



















Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

0 2 4 6 8 10 12 14 16

minus24

minus28


Qc max (MPa)

0 2 4 6 8 10 12

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28


Rf max ()



119891

x (m)

y(m

)

CPTU9CPTU7

CPTU4

CPTU8

CPTU5

CPTU1

CPTU3

CPTU2

CPTU6

20

51

53

54

5453 52

56

58

61

61

59

63

5656

5861 53

57

59

61

63

65

63

66

20

25

30

35

40

45

50

55

60

25 30 35 40 45 50 55 60

48

44

40

36

32

28

24

20

Resis

tivity

(Ohm

m)

(a)

Resis

tivity

(Ohm

m)

x (m)

y(m

)

20

20

25

30

35

40

45

50

55

60

25 30 35

118

40 45 50 55 60

CPTU9 CPTU3

CPTU6CPTU1CPTU8

CPTU4 CPTU5

CPTU7110105

98

8885

82

80

92

48

44

40

36

32

28

24

20

82 80

78

75

72

85

90

82

105 75

78

80

82

85927

5

(b)





Acknowledgment


References





























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










(a) (b)

(c)



2400

2000

1600

1200

800

400

00 1 2 3 4 5 6 7 8 9 10 11 12

Com

pres

sive s

tress

(kPa

)

Axial strain ()





119876119888pre sim 7MPa


119865119904pre sim 02MPa

119865119904post sim 05MPa

119877119891pre sim 25

119877119891post sim 45

(2)











119888val-



140

120

100

80

60

40

20

00

Test number1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Com

pres

sibili

ty an

d el

astic

ity m

odul

i (M

Pa)

0

500

1000

1500

2000

2500

Com

pres

sive s

treng

th120590c

(kPa

)ME pre

E pre

ME post

E post

M998400

M998400

E15 pre



119864and1198721015840

119864(from



















Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

0 2 4 6 8 10 12 14 16

minus24

minus28


Qc max (MPa)

0 2 4 6 8 10 12

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28


Rf max ()



119891

x (m)

y(m

)

CPTU9CPTU7

CPTU4

CPTU8

CPTU5

CPTU1

CPTU3

CPTU2

CPTU6

20

51

53

54

5453 52

56

58

61

61

59

63

5656

5861 53

57

59

61

63

65

63

66

20

25

30

35

40

45

50

55

60

25 30 35 40 45 50 55 60

48

44

40

36

32

28

24

20

Resis

tivity

(Ohm

m)

(a)

Resis

tivity

(Ohm

m)

x (m)

y(m

)

20

20

25

30

35

40

45

50

55

60

25 30 35

118

40 45 50 55 60

CPTU9 CPTU3

CPTU6CPTU1CPTU8

CPTU4 CPTU5

CPTU7110105

98

8885

82

80

92

48

44

40

36

32

28

24

20

82 80

78

75

72

85

90

82

105 75

78

80

82

85927

5

(b)





Acknowledgment


References





























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










140

120

100

80

60

40

20

00

Test number1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Com

pres

sibili

ty an

d el

astic

ity m

odul

i (M

Pa)

0

500

1000

1500

2000

2500

Com

pres

sive s

treng

th120590c

(kPa

)ME pre

E pre

ME post

E post

M998400

M998400

E15 pre



119864and1198721015840

119864(from



















Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

0 2 4 6 8 10 12 14 16

minus24

minus28


Qc max (MPa)

0 2 4 6 8 10 12

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28


Rf max ()



119891

x (m)

y(m

)

CPTU9CPTU7

CPTU4

CPTU8

CPTU5

CPTU1

CPTU3

CPTU2

CPTU6

20

51

53

54

5453 52

56

58

61

61

59

63

5656

5861 53

57

59

61

63

65

63

66

20

25

30

35

40

45

50

55

60

25 30 35 40 45 50 55 60

48

44

40

36

32

28

24

20

Resis

tivity

(Ohm

m)

(a)

Resis

tivity

(Ohm

m)

x (m)

y(m

)

20

20

25

30

35

40

45

50

55

60

25 30 35

118

40 45 50 55 60

CPTU9 CPTU3

CPTU6CPTU1CPTU8

CPTU4 CPTU5

CPTU7110105

98

8885

82

80

92

48

44

40

36

32

28

24

20

82 80

78

75

72

85

90

82

105 75

78

80

82

85927

5

(b)





Acknowledgment


References





























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

0 2 4 6 8 10 12 14 16

minus24

minus28


Qc max (MPa)

0 2 4 6 8 10 12

Dep

th (m

)

minus20

minus16

minus12

minus08

minus04

00

minus24

minus28


Rf max ()



119891

x (m)

y(m

)

CPTU9CPTU7

CPTU4

CPTU8

CPTU5

CPTU1

CPTU3

CPTU2

CPTU6

20

51

53

54

5453 52

56

58

61

61

59

63

5656

5861 53

57

59

61

63

65

63

66

20

25

30

35

40

45

50

55

60

25 30 35 40 45 50 55 60

48

44

40

36

32

28

24

20

Resis

tivity

(Ohm

m)

(a)

Resis

tivity

(Ohm

m)

x (m)

y(m

)

20

20

25

30

35

40

45

50

55

60

25 30 35

118

40 45 50 55 60

CPTU9 CPTU3

CPTU6CPTU1CPTU8

CPTU4 CPTU5

CPTU7110105

98

8885

82

80

92

48

44

40

36

32

28

24

20

82 80

78

75

72

85

90

82

105 75

78

80

82

85927

5

(b)





Acknowledgment


References





























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation












Acknowledgment


References





























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation









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