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Paper No. 023184
CD-ROM PAPERDuplication for publication or sale is strictly prohibited
without prior written permissionof the Transportation Research Board
TITLE: EFFECTS OF HIGH GROUNDWATER TABLE AND
CAPILLARY RISE ON PAVEMENT BASECLEARANCE OF GRANULAR SUBGRADES
Author(s): W. Virgil Ping, Haitao Liu,
Chaohan Zhang, and Zenghai Yang
Department of Civil and Environmental Engineering
Florida A&M University - Florida State University
College of EngineeringTallahassee, Florida 32310-6046
(850) 410-6129 (PH) (850) 410-6142 (FAX)
e-mail: ping@eng.fsu.edu
and
David Horhota
Florida Department of Transportation
Gainesville, Florida 32609
Transportation Research Board
81st
Annual Meeting
January 13-17, 2002
Washington, D.C.
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Ping, Liu, Zhang, Yang, and Horhota
EFFECTS OF HIGH GROUNDWATER TABLE AND CAPILLARY
RISE ON PAVEMENT BASE CLEARANCE OF GRANULAR
SUBGRADES
ABSTRACT
High groundwater table exerts detrimental effects on the roadway base and the whole pavement.Base clearance guidelines have been developed to prevent water from entering the pavement
system in order to reduce its detrimental effects. This paper presents an experimental study to
evaluate the effects of high groundwater table and the moisture and capillary rise on determiningpavement base clearance for granular subgrades. A full-scale in-lab test-pit test was conducted to
simulate pavement profile and vehicle dynamic impact on the pavement. Three types of granular
subgrades were tested for this study.
The results showed that a 24-inch base clearance was considered adequate for the baseprotection of the A-3 subgrade against high groundwater tables. The A-2-4 soil with relativelyhigh suction value was more susceptible to the change of groundwater table than the A-3 soils.
The percent of fines of subgrade soil can significantly influence its moisture effect on the
resilient modulus.
Key Words: High groundwater table, capillary rise, base clearance, resilient modulus, granularsubgrade
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Ping, Liu, Zhang, Yang & Horhota 1
INTRODUCTION
Roadway pavements must be designed in such a way that water is prevented from entering the
places where it can cause damage. High groundwater table exerts detrimental effects on the
roadway base and the whole pavement. Base clearance guidelines have been developed toprevent water from entering the pavement system in order to reduce its detrimental effects (1). In
these guidelines a minimum height, the clearance, between a groundwater level and a particular
elevation within the pavement system is specified. The guidelines are intended to satisfy twoconcerns: 1) to prevent potential damages to the roadway base due to groundwater saturation or
high moisture content from capillary suction; 2) to achieve the required compaction and stability
during construction operations.
But the prevailing guideline neglects the fact that each roadway is built with a different
type of subgrade material. There can be different geotechnical properties related with different
subgrade soils such as permeability and suction in unsaturated state, which are critical for
capillary behavior (2,3). To assist in evaluating the effects of high groundwater table and the
moisture and capillary rise on determining pavement base clearance for granular subgrades, afull-scale in-lab test-pit test was conducted to simulate pavement profile and vehicle dynamic
impact on the pavement. Three types of granular subgrades were tested for this study. Parameterssuch as soil suction and coefficient of permeability were also measured in the laboratory. The
experimental program is described as follows.
EXPERIMENTAL PROGRAM
A full-scale laboratory evaluation of the three granular subgrade soils was conducted in a test-pit
facility. The stabilized subgrade and base component of a full-scale flexible pavement systemwas simulated in the test-pit facility. Moisture condition was manipulated by raising andlowering the water level in the test-pit. The subgrade materials were tested in different moisture
conditions that simulated different field conditions. Time Domain Reflectometry (TDR) probes
were deployed for measuring the moisture content within each layer of subgrade material in thetest-pit (4,5). The effect of capillary rise was also monitored in the experimental program. The
effect of the dynamic loadings was evaluated using the repeated plate load in the test-pit test.
Subgrade Materials
The soils under investigation in this study were three typical A-3, A-2-4 subgrade materials in
use in Florida representing the percent of fines passing No.200 sieve, which ranged from 4% to
14%. The three soils included Levy County A-3 (4% passing No.200), SR-70 A-3 (8% passingNo.200) and A-2-4 (14% passing No.200). The compaction characteristics were determined in
the laboratory using the modified Proctor (AASHTO T-180) method. The pertinent
characteristics of those subgrade soils are presented in Table 1. The soil suction measurementswere conducted in accordance with the AASHTO T273-86 procedure, except that the soil
samples were remolded. This test method covers the procedure for determining total suction
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Ping, Liu, Zhang, Yang & Horhota 2
force by using thermocouple psychrometers of the Spanner type (2,6). The soil suction versus
moisture content curves are presented in Figure 1 for the three soils.
Test-pit Experimental program
The test-pit facility re-constructs and simulates the subgrade and base components of a flexible
pavement system on a full-scale basis. The major concerns of test-pit test program are thedeformation and equivalent resilient modulus of a layered system under the static loading and
cyclic dynamic loading, which is used in modeling the impact of moving vehicle on the
pavement (7). The cyclic loading of a circular plate was activated with a one-second intervalwithin which the loading and resting periods would be 0.1 and 0.9 second respectively. For the
evaluation of moisture influence on the performance of pavement material, the water table was
kept adjusted within the pit while conducting a plate load test. The TDR probes were deployedwithin the test-pit for the monitor of moisture profile of pavement material.
The capillary action and resilient deformation of the materials under investigation were
evaluated with four levels of groundwater elevation: drained, flooded, intermediate levelsbetween the embankment-subgrade interface, and 12 inches above the embankment. To offsetthe loss due to capillary rise and evaporation, extra water had to be added within the pit to keep
the water table constant at each designated elevation prior to the moisture equilibrium and plate
load test.
The complete setup of test-pit experiment is mainly comprised of two parts full-scale
test-pit and loading system. A schematic view of the test-pit and the loading system andcompaction equipment is illustrated in Figure 2.
Test Arrangement
Levy County A-3 subgrade (4% passing No. 200) had been compacted and experimented withinhalf of the test-pit (8 feet by 6 feet). SR-70 A-3 (8% passing No. 200) and A-2-4 (14% passing
No. 200) subgrades had been compacted and experimented within one test-pit (8 feet by 12 feet).
Separated by wooden partitions, each of these subgrades accounted for half of the test-pit area.
During the test, three feet of subgrade material was compacted within the test-pit under
its optimum moisture condition. The subgrade materials were compacted into seven layers. With
the exception of the first and last lifts three inches thick, each lift was six inches in thickness.
The TDR probe was embedded on each of these layers respectively staggering one another. Thecircular rigid loading plate was positioned on the mid-point between two columns of vertically
arranged TDR probes. The TDR probe installation and test layout for the SR-70 A-3 and A-2-4
subgrades is shown in Figure 3.
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Ping, Liu, Zhang, Yang & Horhota 3
Phase I: Levy County A-3 Soil
A series of plate load tests were conducted at each time when the moisture equilibrium was
achieved for Levy County A-3 soil after adjusting the water table level. The designated testnumbers and their corresponding loading conditions for Phase I are summarized in Table 2.
Phase II: SR-70 A-3 and A-2-4 Soils
A total of fifteen plate load tests were conducted for both SR-70 A-3 and A-2-4 soils in the phase
II test-pit test after the establishment of moisture equilibrium for the soils. The designated test
numbers and their corresponding loading conditions for phase II are also summarized in Table 2.
Method of Analysis
The resilient modulus obtained from the plate load tests on subgrade is based on Boussinesqs
theory of deflections at the center of a circular plate. Burmister has extended this theory to a two-layer elastic system (8). The layers are assumed to be homogeneous, isotropic, and elastic solid
with a continuous interface with the bottom layer being infinite in depth. Under thesecircumstances, the equivalent single-layer resilient modulus under the cyclic loading on a two-layer system (base and subgrade layers) can be derived from the theory of elasticity:
)1(2
=
R
eR
paE (1)
where: EeR = equivalent resilient modulus of a two-layer
system
R = resilient deflection of the two-layer
system at N (number of cyclic load)
p = surcharge pressure from the circular plate
a = radius of the circular plate= Poissons ratio
If=0.35 and 0.50, Equation 1 will be as follow:
R
eR
paE
=
38.1(=0.35) (2)
R
eR
paE
=
18.1(=0.50) (3)
For this study, =0.35 was used for the granular subgrades. The equivalent modulus is
an excellent criterion for the evaluation of the strength of pavement materials (7).
EXPERIMENTAL RESULTS
The experimental results are summarized and presented in this section. A typical figure showing
the plate load test results is presented in Figure 4 for Levy County A-3 soil. The equivalent
modulus values under different loading and water table conditions are presented in Figures5,6,7,8,9, and 10 for the Levy County A-3, SR-70 A-3, and SR-70 A-2-4 soils, respectively. For
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Ping, Liu, Zhang, Yang & Horhota 4
each plate load test conducted, two figures are grouped together to represent a specific set of
plate load test results. The presented equivalent modulus value for each test was taken as theaverage modulus value of over 10,000 load cycles.
In the capillary rise study, the height of the capillary rise was the vertical distance
between the water table and the highest elevation where the moisture increase existed. The
capillary rise results for the three soils are summarized in Table 3.
ANALYSIS OF EXPERIMENTAL RESULTS
The contribution of a rise in capillary moisture to the decrease of the equivalent modulus was
quite different for different soils (see Figure 11). For Levy County and SR-70 A-3 soils, the
extensive accumulation of capillary moisture within capillary fringe after the adjustment of thegroundwater tables seemed to have little influence on the equivalent modulus. For the SR-70 A-
2-4 soil with a relatively higher capillary potential, a minor moisture increase in the capillary
zone would result in a 20% decrease in equivalent modulus. This is probably because the
increase of moisture content may have caused a more drastic suction decrease for a high suctionsoil, thus resulting in a more obvious decrease of resilient modulus value under the plate load. If
this assumption is true, then the design highwater clearance is more critical for high suction soilsthan for low suction soils.
Discussion
The fluctuation of resilient modulus as a result of the change in the groundwater table, illustrated
that mere soil structure itself was not the controlling factor for the elastic deformation (9,10). But
the mere presence of water did not guarantee a decreased resilient modulus. No significantdifference occurred for the resilient modulus of extremely coarse gravel whether it was flooded
or completely drained.
In the literature, the suggestion has been raised that correlating the resilient behavior ofsoil with the suction value it assumed, may be more appropriate than using moisture content or
degree of saturation as indicators for the analysis of subgrade resilient behavior (3). For aspecific subgrade soil, the resilient modulus is more or less dependent on the capillary moisture
developed from the groundwater table. However, for different subgrade materials, the resilient
modulus is more dependent on the capillary potential of each individual soil (suction value)rather than capillary moisture accumulated within a capillary zone.
Case Studies
The practical significance of designing base clearances is to optimize the thickness of the
pavement layers above the groundwater level including a structural asphalt concrete layer
satisfying both the economic and safety designs. A case study utilizing the measured resilientmodulus data to design the required thickness of flexible pavement layer with respect to different
groundwater levels would help to gain an insight into the economic aspect of importance for
such base clearances.
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Ping, Liu, Zhang, Yang & Horhota 5
The AASHTO Guide for Design of Pavement Structures (1986 and 1993) was adopted
for this case study relative to the change of groundwater table at SR-70 (11). In this designapproach, the effective roadbed soil resilient modulus (MR) to be used in the AASHTO design
equation was taken from the equivalent modulus of composite pavement profile in test-pit tests,
which is presented in Figures 5,7, and 9. The two schemes were studied in the following ways:
1. 50 psi plate loading with the equivalent modulus of the composite section for 5-inch limerockbase, 36-inch stabilized subgrade layer, and embankment
2. 20 psi plate loading with the equivalent modulus of the composite section for 36-inch
stabilized subgrade plus embankment
Table 4 summarizes the results of the required structural number and design thickness for
the asphalt concrete layer under different groundwater level variations.
The required thickness of the asphalt concrete layer was more sensitive to the
groundwater table variation for the SR-70 A-2-4 subgrade than for the SR-70 A-3 subgrade
under the same thickness (5 in.) of limerock base. This was especially obvious when the
groundwater table was raised from 12 in. to 36 in. above the embankment (i.e., 0 in. below the
limerock base). For the case of the 50-psi plate loading with 5-in. limerock base, the relationshipbetween the required asphalt concrete thickness and the groundwater table level was nearly
linear for the SR-70 A-3 subgrade. While for the SR-70 A-2-4 soil, the required thickness ofstructural asphalt layer was accelerated by the increase of the groundwater level.
Summary
The results of this case study for State Road 70 indicated that for the A-2-4 subgrade, a slightincrease of the groundwater table (12 in. or higher above the embankment) would demand an
exponential increase for the thickness of asphalt concrete layer in order to have the same quality
pavement performance. Thus, the most safe and economic way for the design of pavement is still
to maintain an adequate base clearance between the groundwater table and the bottom of the baselayer, which is essential for fine-grained subgrade materials (12).
CONCLUSIONS
Based upon the analysis and findings of this experimental study, the conclusions are summarized
below:1. Both Levy County A-3 soil and SR-70 A-3 soil were good subgrade materials to be used for
roadway pavements. A 24-inch base clearance was adequate for the base protection against
high groundwater tables.2. The percentage of fines passing through No. 200 sieve of a subgrade soil can significantly
influence its moisture effect on the resilient modulus. The SR-70 A-2-4 soil with relatively
high suction value was more susceptible to the change of groundwater table than the A-3soils. The resilient modulus deteriorated drastically when the groundwater table reached to the
top of the stabilized subgrade layer.
3. The A-3 soils with a higher permeability had a faster accumulation of capillary moisturewithin the capillary fringe than the A-2-4 soil with a lower unsaturated permeability. The
amount of capillary moisture incurred by a high water table was more dependent on the
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permeability than the capillary potential (soil suction) during a short period of time. For the
SR-70 A-2-4 soil having the highest suction, both the height of capillary rise and the amountof moisture developed over a short term were the lowest among the soils investigated.
4. For different subgrade materials, the resilient modulus was more influenced by the capillary
potential (suction) of a soil than the capillary moisture accumulated within the capillary fringe
above the water table.5. Case studies for the SR-70 project showed that the required thickness of the asphalt concrete
layer increased with an increase in the groundwater level above the embankment. The increaseof asphalt concrete thickness was more pronounced for the A-2-4 soil when the water table
was raised from 12 in. to 36 in. (i.e., 24 in. to 0.0 in. base clearance) above the embankment.
ACKNOWLEEDMENTS
Funding for this research was provided by Florida Department of Transportation (FDOT) andFederal Highway Administration (FHWA). Rick Renna, David Chiu, and Morteza Alian were
the FDOT project managers. The FDOT Research Center, through the assistance of Richard
Long and his stuff, provided financial and contractual support. Rick Venick and Ron Lewis ofthe FDOT State Materials Office provided technical support for the test-pit study.
REFERENCES
1. Elfino, M. K, An Evaluation of Design highwater Clearances for Pavements, Ph. D.
Dissertation, Dept. Of Civil Engineering, University of Florida, Gainesville, FL 1986.2. Fredlund, D. G., and H. Rahardjo, Soil Mechanics for Unsaturated Soils, John Wiley & Sons,
New York, 1993.
3. Edil, T. B., and Sabri E. Motan, Soil Water Potential and Resilient Behavior of Subgrade
Soils. In Transportation Research Record No. 705, TRB, National Research Council,Washington D.C., 1979, pp. 54-63.
4. Campbell Scientific Inc., CS615 Water Content Reflectometer, Logan, UT, 1998.
5. Klemunes, J., Determining Soil Volumetric Moisture Content Using Time Domain
Reflectometry, Office of Engineering Research & Development, Federal HighwayAdministration, Mclean, VA, 1998.
6. Klute, A.Method of Soil Analysis: Part I-Physical and Mineralogical Methods. 2nd ed. Soil
Science Society of American, Madison, Wis., 1986.7. Ping, W. V., and Z. Yang, Experimental Verification of Resilient Deformation for Granular
Subgrades. In Transportation Research Record 1639, TRB, National Research Council,
Washington D.C. 1998.
8. Burmister, D.M. The Theory of Stresses and Displacements in Layered Systems andApplication to the Design of Airport Runways. Proc., of the Highway Research Board, 1943.
9. Hicks, R. G. and C. L. Monismith, Factors Influencing the Resilient Response of GranularMaterials. In Highway Research Record No.345, Highway Research Board, Washington
D.C., 1971.
10. Lekarp, F., U. Isacsson, and A. Dawson, State of the Art. I: Resilient Response of UnboundAggregates,Journal of Transportation Engineering, Vol. 126, Reston, VA, 2000, pp. 66-83.
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Ping, Liu, Zhang, Yang & Horhota 7
11.AASHTO guide for Design of Pavement Structures. Joint Task Force on Pavements, Highway
Sub-committee on Design, American Association of State Highway and TransportationOfficials, Vols. I & II, 1986 and 1993.
12. Huang, Y. H., Pavement Analysis and Design, Prentice-Hall, Inc., Upper Saddle River, NJ,
1993.
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Ping, Liu, Zhang, Yang & Horhota 8
List of Tables
Table 1 Characteristics of Tested Subgrade Materials
Table 2 Test Sequence for Test-pit Experimental Program
Table 3 Summary of Capillary Rise for Subgrade Materials in Test-pit Test
Table 4 Results of Case Study for SR-70 -- Required Thickness of Asphalt Concrete under
Different Groundwater Tables
List of Figures
Figure 1 Summary of Suction vs. Water Content for Tested Soils
Figure 2 Test Pit Loading System and Compaction Equipment
Figure 3 Test-pit Setup for SR-70 A-3 & A-2-4 Subgrades
Figure 4 Levy County A-3 Soil EQ Modulus vs. Number of Cycles under Different Water Tables
(20 psi with Limerock)
Figure 5 Levy County A-3 Soil EQ Modulus
Figure 6 Levy County A-3 Soil Moisture Profile under Plate Load Test
Figure 7 SR-70 A-3 Soil EQ Modulus
Figure 8 SR-70 A-3 Soil Moisture Profile under Plate Load Test
Figure 9 SR-70 A-2-4 Soil EQ Modulus
Figure 10 SR-70 A-2-4 Soil Moisture Profile under Plate Load Test
Figure 11 Equivalent Modulus vs. Water Table
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Table 1 Pertinent Characteristics of Tested Subgrade Materials
+ LBR: Limerock Bearing Ratio, LBR=1.25CBR
Table 2 Test Sequence for Test-pit Experimental ProgramPhase I Levy County A-3 soil
Water Table
(inch)Test Number Plate Load (psi)
5-inch Base Layer
(Limerock)
Test Date
Mo./Day/Year
-20 1-L1 20 No 12/30/98
0 1-L2 20 No 2/5/99
+12 1-L3 20 No 2/26/99
+12 1-L4 20 Yes 3/23/99
+12 1-L5 50 Yes 3/24/99
+36 1-L6 50 Yes 3/31/99
+36 1-L7 20 Yes 4/1/99
Phase II SR-70 A-3 and A-2-4 soils
Water Table
(inch)Test Number Plate Load (psi)
5-inch Base Layer
(Limerock)
Test Date
Mo./Day/Year
0 2-N1(A-3) 20 No 7/19/99
0 2-S1(A-2-4) 20 No 7/20/99
+12 2-S2(A-2-4) 20 No 8/24/99
+12 2-N2(A-3) 20 No 8/25/99+12 2-S3(A-2-4) 50 Yes 9/2/99
+12 2-N3(A-3) 50 Yes 9/3/99
+36 2-N4A(A-3) 50 Yes 9/29/99
+36 2-S4(A-2-4) 50 Yes 9/30/99
+36 2-N4B(A-3) 50 Yes 10/5/99
-24 2-S5(A-2-4) 50 Yes 12/28/99
-24 2-N5(A-3) 50 Yes 12/29/99
-24 2-N6(A-3) 50 Yes 1/4/00
-24 2-S6(A-2-4) 50 Yes 1/5/00
+36 2-S7(A-2-4) 50 Yes 2/1/00
+36 2-N7(A-3) 50 Yes 2/2/00
MaterialNo.200 Passing
(%)Dry Density
(kN/M3)
OptimumMoisture (%)
LBR+
Permeability(cm/second)
Levy Co. A-3 4 16.7 9.5 22 5.52*10-3
SR-70 A-3 8 17.6 11.5 45 2.06*10-3
SR-70 A-2-4 14 19.2 10.6 124 1.97*10-5
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Table 3 Summary of Capillary Rise for Subgrade Materials in Test-pit Test
* Capillary rise passes through 12 in. standard A-3 sand within embankment
** Capillary rise passes through 12 in. standard A-3 sand within embankment
Soil TypeWater Table
(inches)
Time
Period
(days)
-20 to 0.0 29
0.0 to +12 19
-24 to -12 14
-12 to 0.0 17
0.0 to +12 28
-24 to -12 24
-12 to 0.0 42
0.0 to +12 40
15+12 **
>33
15
SR-70 A-2-4
Soil (14%)
Yes 5/17 to 6/10
No 6/10 to 7/22
Capillary
Rise
(inches)
Moisture
Stabilized
at each
Level
Moisture Data
recorded from
(Date: 1999)
21
13+12 *
21
Levy County
A-3 Soil
(4%)
Yes 1/5 to 2/3
Yes 2/5 to 2/23
26
>24
No 7/22 to 9/1
SR-70 A-3
Soil (8%)
Yes 5/17 to 5/31
Yes 6/10 to 6/27
Yes 7/22 to 8/20
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Table 4 Results of Case Study for SR-70 -- Required Thickness of Asphalt Concrete under
Different Groundwater Tables
-20 in.(Drained)
0.0 in. +12 in.
Structural Number N/A 1.54 1.74
Thickness of Asphalt
Concrete (in.)N/A 3.50 3.96
Structural Number N/A 1.68 1.92
Thickness of Asphalt
Concrete (in.)N/A 3.82 4.36
Structural Number N/A 2.44 2.64
Thickness of Asphalt
Concrete (in.)N/A 5.55 6.01
Structural Number N/A 2.58 2.82
Thickness of Asphalt
Concrete (in.)N/A 5.86 6.40
-24 in.
(Drained)+12 in. +36 in.
Structural Number 2.45 2.88 3.25
Thickness of Asphalt
Concrete (in.)5.58 6.54 7.38
Structural Number 2.85 3.21 4.63
Thickness of Asphalt
Concrete (in.)6.47 7.29 10.53
Plate Load Test (20 psi w/o Limerock)
Water Table (above Embankment)
SR-70
A-3
(Assumed
Limerock
10 inch)
SR-70
A-2-4
(Assumed
Limerock
10 inch)
Water Table (above Embankment)
SR-70 A-3
SR-70 A-2-4
SR-70
A-3
(Assumed
Limerock
5 inch)
SR-70
A-2-4
(Assumed
Limerock
5 inch)
Plate Load Test (50 psi with 5-inch Limerock)
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Figure 1 Summary of Suction vs. Water Content for Tested Soils
Soil Suction vs Water Content
0
50
100
150
200
250
300
350
400
450
4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0
Moisture Content, %
SoilSuction,
kPa
Levy Co. A-3
SR-70 A-3
SR-70 A-2-4
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Figure 2 Test-pit Loading System and Compaction Equipment
SAND 305mm
GRAVEL05mm
LOADING DEVICE
RIVERGRAVEL
24 WFBEAM
WATERSOURCE
Schematic View of Test-pit
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Figure 3 Test-pit Setup for SR-70 A-3 & A-2-4 Subgrades
(* Sequence of Water Table Adjustment)
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Figure 4 Levy County A-3 Soil EQ Modulus vs. Number of Cycles under Different Water Tables
(20 psi with Limerock)
Levy Count y A-3 Soil, EQ Modulus vs. Number o f Cycles
0.00
50.00
100.00
150.00
200.00
250.00
300.00
350.00
400.00
1 10 100 1000 10000 100000
Number of Cycles
EquivalentModulus,M
p
W . T. at +12 in. 1-L4
W . T. at +36 in. 1-L7Subgrade
Embankment
20psi
Limerock
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Equivalent Modulus of Levy County A-3 Soil
178.0
144.7
131.6
226.4
264.2
196.4
170.1
0
50
100
150
200
250
300
1-L1 1-L2 1-L3 1-L4 1-L5 1-L6 1-L7
Test Number
EquivalentModulus,
MPa
Levy County A-3 Soil Moisture Profile under Plate Load Test
0
3
6
9
12
15
18
21
24
27
30
33
36
0 5 10 15 20
Moisture Content, %
Elevation,
in.
1-L1, -20 in. W.T.
1-L2, 0 in. W.T.
1-L3, +12 in. W.T.
1-L4, +12 in. W.T.
1-L5, +12 in. W.T.
1-L6, +36 in. W.T.
1-L7, +36 in. W.T.
Figure 5 Levy County A-3 Soil EQ Modulus
Figure 6 Levy County A-3 Soil Moisture Profile under Plate Load Test
Limerock layer: 1-L4, 1-L5, 1-L6, and 1-L7
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Equivalent Modulus of SR-70 A-3 Soil
499.1
408.2
203.7
174.5
299.7
229.6208.0
0
100
200
300
400
500
600
2-N5 2-N6 2-N1 2-N2 2-N3 2-N4 2-N7
Test Number
EquivalentModulus,
MPa
SR-70 A-3 Soil Moisture Profile under Plate Load Test
0
3
6
9
12
15
18
21
24
27
30
33
36
0 5 10 15 20 25
Moisture Content, %
Elevation,
in.
2-N5, -24 in. W.T.
2-N6, -24 in. W.T.
2-N1, 0 in. W.T.
2-N2, +12 in. W.T.
2-N3, +12 in. W.T.
2-N4, +36 in. W.T.
2-N7, +36 in. W.T.
Figure 7 SR-70 A-3 Soil EQ Modulus
Figure 8 SR-70 A-3 Soil Moisture Profile under Plate Load Test
Limerock layer: 2-N3, 2-N4, 2-N5, 2-N6, and 2-N7
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Equivalent Modulus of SR-70 A-2-4 Soil
233.0
383.4
183.0
153.6
226.6
105.7
60.7
0
50
100
150
200
250
300
350
400
450
2-S5 2-S6 2-S1 2-S2 2-S3 2-S4 2-S7
Test Number
EquivalentModulus,
MPa
SR-70 A-2-4 Soil Mosture Profile under Plate Load Test
0
3
6
9
12
15
18
21
24
27
30
33
36
0 5 10 15 20 25 30 35
Moisture Content, %
Elevation,
in.
2-S5, -24 in. W.T.
2-S6, -24 in. W.T.
2-S1, 0 in. W.T.
2-S2, +12 in. W.T.
2-S3, +12 in. W.T.
2-S4, +36 in. W.T.2-S7, +36 in. W.T.
Figure 9 SR-70 A-2-4 Soil EQ Modulus
Figure 10 SR-70 A-2-4 Soil Moisture Profile under Plate Load Test
Limerock layer: 2-S3, 2-S4, 2-S5, 2-S6, and 2-S7
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Figure 11 Equivalent Modulus vs. Water Table
Average Equivalent Modulus vs Water Table
(20 psi without Lim erock)
0
50
100
150
200
250
300
350
400
450
500
-24 -18 -12 -6 0 6 12 18
Ground Water Table, in.
AverageEQ
Modulus,
Mpa
Levy Co. A-3
SR-70 A-3
SR-70 A-2-4
Ave rage Equivalent Modulus vs Water Table
(50 psi with Limerock)
0
50
100
150
200
250
300
350
400
450
500
-36 -24 -12 0 12 24 36 48
Ground Water Table, in.
AverageEQ
Mod
ulus,
Mpa
Levy Co. A-3
SR-70 A-3
SR-70 A-2-4
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