guidelines natm paper schubert

SCHUBERT, GORICKI AND RIEDMÜLLER: GUIDELINE FOR THE GEOMECHANICAL DESIGN OF UNDERGROUND STRUCTURES

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chanical Design of UndergroundStructures with ConventionalExcavation

By Wulf Schubert, Andreas Goricki and Gunter Riedmüller

Richtlinie für die geomechanische Planung vonUntertagebauarbeiten mit zyklischem Vortrieb

Die Werkvertragsnorm ÖNORM B2203 regelt die vertragli-chen Belange im Untertagebau. Die Fassungen von 1983und 1994 enthalten auch Elemente der Gebirgstypisie-rung. Im Zuge der Überarbeitung der ÖN B2203 im Jahr2001 wurden alle Belange der Gebirgscharakterisierungaus der Werkvertragsnorm eliminiert. Eine Arbeitsgruppeder Österreichischen Gesellschaft für Geomechanik er-stellte eine Richtlinie für die geomechanische Planung vonUntertagebauarbeiten mit zyklischem Vortrieb, die im Ok-tober 2001 erschien und auf welche die ÖNORM B2203-1Bezug nimmt. Die Richtlinie beschreibt die für eine Pla-nung und Bauausführung von Untertagebauten erforderli-chen Schritte aus technischer Sicht. Der in der Richtlinieskizzierte schrittweise Vorgang soll einen ingenieurmäßi-gen Zugang zur Thematik fördern.

In der Planungsphase basieren die Vortriebs- und Aus-baukonzepte auf Gebirgsverhaltenstypen, die aus den Ge-birgsarten und den das Verhalten beeinflussenden Fakto-ren abgeleitet werden. Das Systemverhalten beschreibtdas Verhalten des Systems Ausbau-Gebirge. Die Ermitt-lung des Systemverhaltens stützt sich auf Datenauswer-tung ausgeführter Projekte und wird durch numerischeSimulationen an geeigneten Modellen unterstützt. Wäh-rend des Baus wird die Planung mithilfe von geologischenAufnahmen, Beobachtungen und Auswertung von Messun-gen verfeinert. Das vorhergesagte und beobachtete Verhal-ten wird laufend verglichen. Treten Abweichungen zwi-schen prognostiziertem und beobachtetem Verhalten auf,ermöglicht die systematische Vorgangsweise eine umfas-sende Analyse. Damit wird eine ständige Weiterentwick-lung des Tunnelbaus ermöglicht und gefördert.

Bei Einhaltung des in der Richtlinie vorgegebenen Ab-laufs ist eine relativ einfache technische Überprüfung derPlanung möglich. Die in der Richtlinie geforderte durch-gängige Dokumentation sollte zudem ermöglichen, die

Erfahrungen verschiedener Bauwerke besser nutz- undvergleichbar zu machen, was auf längere Sicht zu einerVerbesserung von Planungs- und Baumethoden führensollte.

The Austrian Standard B2203 regulates the contractual pro-cedure for underground works. The versions of 1983 and1994 contained descriptions of rock mass types. In thecourse of updating the Standard in 2001 it was decided toremove all rock mass characterization issues from theStandard. A working group of the Austrian Society for Geo-mechanics (OGG) established a guideline for the geome-chanical design of underground structures, which was pub-lished in October 2001, and to which the Standard B2203-1refers (1). The main topic of the guideline is the develop-ment of a consistent procedure for the determination ofexcavation and support. The outlined step by step proce-dure promotes an engineering approach to the design andconstruction of tunnels.

In the pre-construction phase support concepts arebased on rock mass behaviour types developed from rockmass types and influencing factors. The system behaviourdescribes the rock mass-support interaction which is basedon previous experience (including data base knowledge),analytical and numerical simulations. During construction,geological face mapping, geotechnical monitoring, and ob-servations allow the design of support and excavationmethods to be completed. The observed and predicted be-haviours are compared by evaluating monitored deforma-tions, support utilization, and overbreak volume. Devia-tions between the observed and predicted behaviour leadto a re-evaluation of the process resulting in modificationsto the support and excavation methods.

The consistent procedure allows designs to be technical-ly reviewed and audited. The standardized approachshould also allow the establishment of knowledge basedexpert systems, which in the long run will improve designand construction methods.

Currently, there are no standardized proce-dures to determine excavation and support

for underground openings. This lack of con-sistency makes it difficult to technically reviewor audit designs, collect, evaluate, and comparedata from different sites and designs.

A sound and economical tunnel design de-pends on a realistic geological model (2), a qual-ity rock mass characterization, and the assess-ment of influencing factors such as primary

stresses, groundwater, and the size of under-ground opening. Despite this requirement it isstill current practice to base the tunnel designprimarily on experience, basic empirical calcu-lations, and standardized rock mass classifica-tion systems. Additionally, the on site decisionson excavation and support modifications are fre-quently based more on intuition than on analy-ses. This is especially true for tunnels with highoverburden in complex geological conditions

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FELSBAU 21 (2003) NO. 4

where limited information is available in the pre-construction phase.

On the other hand, the quantitative rock massclassification systems presently in use (3, 4, 5, 6)have severe shortcomings. One of the main defi-ciencies is that the classification parameters areuniversally applied to all rock mass types. Espe-cially in heterogeneous and poor ground condi-tions these classification methods may providemisleading results, while other shortcomings in-clude the lack of consideration for different rockmass failure modes and ground-support interac-tion (7). These schematic procedures have thepotential to make tunnel design appear rathersimple. Frequently, a few specific parametersare determined and simple classification formu-las are applied to achieve a rating. Then with adesign chart a support method is determined. Noreference is made to project specific require-ments or to boundary conditions.

For this reason, it was decided to develop aconsistent method for tunnel design, from thepre-construction phase through the tunnel con-struction, applicable to all rock mass conditions.In general, the final design process continues

Fig. 1 Flow chart ofthe basic procedure of

excavation and sup-port design for under-

ground structures.Bild 1 Flussdia-

gramm der grundsätz-lichen Vorgangsweise

zur geotechnischenPlanung von Ausbruch

und Stützung vonUntertagebauten.

into the construction phase. The procedure de-veloped describes a transparent and unbiaseddecision making process and was published inthe form of a guideline (8).

The guideline clearly distinguishes betweenrock and rock mass descriptions, behaviour of therock mass as a result of the excavation, and thesystem behaviour resulting from excavation andsupport. The minimum requirements for the doc-umentation of each step are given in the guideline.

First the procedure for the design phases isbriefly described, and then the procedures forthe construction phase are discussed, as they areoutlined in the guideline.

Procedure during design

The geotechnical design, as part of the tunneldesign, serves as a basis for approval proce-dures, the tender documents (determination ofexcavation classes and their distribution), andthe determination of the excavation and supportmethods used on site (9).

The flow chart (Figure 1) shows the basic pro-cedure, consisting of five general steps, to devel-op the geotechnical design, beginning with thedetermination of the rock mass types and endingwith the definition of excavation classes. Duringthe first two steps statistical or probabilisticanalyses should be used to account for the varia-bility and uncertainty in the key parameter val-ues and influencing factors, as well as their dis-tribution along the projects route (10). The prob-abilistic analyses are then continued throughoutthe entire process as necessary, resulting in botha risk analysis and a distribution of excavationclasses on which the tender documents can bebased (11).

Step 1 – determination ofrock mass types (RMT)

The first step starts with a description of the ba-sic geologic architecture and proceeds by defin-ing geotechnically relevant key parameters foreach ground type. The key parameters valuesand distributions are determined from availableinformation or estimated with engineering andgeological judgment. Values are constantly up-dated as pertinent information is obtained. Rockmass types are then defined according to theirkey parameters. The number of rock mass typeselaborated depends on the project specific geo-logical conditions and on the stage of the designprocess.

Physical and hydraulic parameters have to beestablished for each rock mass type (12, 13, 14).

Step 2 – determination of rockmass behaviour types (BT)

The second step involves evaluating the potentialrock mass behaviours considering each rockmass type and local influencing factors, includ-ing the relative orientation of relevant disconti-


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nuities to the excavation, ground water condi-tions, stress situation, etc. (15, 16, 17). Thisprocess results in the definition of project specif-ic behaviour types.

The rock mass behaviour has to be evaluatedfor the full cross sectional area without consider-ing any modifications including the excavationmethod or sequence and support or other auxil-iary measures.

Eleven general categories are listed in theguideline (Table). In case more than one behav-iour type is identified in one of the general catego-ries, sub types have to be assigned. A concise de-scription of the applicable rock mass types, theinfluencing factors, the specific behaviour, failuremodes, as well as estimates of the displacementsfor each behaviour type is required.

The rock mass behaviour types form the basisfor determining the excavation and supportmethods as well as assist in evaluating monitor-ing data during the excavation.

Step 3 – determination of theexcavation and support

Based on the defined project specific behaviourtypes, different excavation and support meas-ures are evaluated and acceptable methods aredetermined. The system behaviour (SB) is a re-sult of the interaction between the rock massbehaviour and the selected excavation and sup-port schemes. The evaluated system behaviourhas to be compared to the defined requirements.If the system behaviour does not comply with therequirements, the excavation or support schemehas to be modified until compliance is obtained.It is emphasized, that different boundary condi-tions or different requirements may lead to dif-ferent support and excavation methods for thesame behaviour type even within one project.

Figure 2 illustrates the process of determina-tion of the behaviour type on the full, unsupport-ed cross section, and the influence of the reduc-tion of the face height, and finally the system be-haviour of the supported top heading. Once theacceptable excavation and support methodshave been determined both risk and economicanalyses should be performed to allow appropri-ate assessments during the tender process (11).

Behaviour type (BT) Description of potential failure modes/mecha-nisms during excavation of the unsupported rockmass

1 Stable Stable rock mass with the potential of small localgravity induced falling or sliding of blocks

2 Stable with the potential of Deep reaching, discontinuity controlled, gravity in-discontinuity controlled duced falling and sliding of blocks, occasional localblock fall shear failure

3 Shallow shear failure Shallow stress induced shear failures in combina-tion with discontinuity and gravity controlled failureof the rock mass

4 Deep seated shear failure Deep seated stress induced shear failures andlarge deformation

5 Rock burst Sudden and violent failure of the rock mass,caused by highly stressed brittle rocks and therapid release of accumulated strain energy

6 Buckling failure Buckling of rocks with a narrowly spaced disconti-nuity set, frequently associated with shear failure

7 Shear failure under low Potential for excessive overbreak and progressiveconfining pressure shear failure with the development chimney type

failure, caused mainly by a deficiency of side pres-sure

8 Ravelling ground Flow of cohesionless dry or moist, intensely frac-tured rocks or soil

9 Flowing ground Flow of intensely fractured rocks or soil with highwater content

10 Swelling Time dependent volume increase of the rock masscaused by physical-chemical reaction of rock andwater in combination with stress relief, leading toinward movement of the tunnel perimeter

11 Frequently changing Rapid variations of stresses and deformations,behaviour caused by heterogeneous rock mass conditions or

block-in-matrix rock situation of a tectonic melange(brittle fault zone)

Table General categories of rock mass behaviour types.Tabelle Übergeordnete Kategorien von Gebirgsverhaltenstypen.

Step 4 – geotechnical report –baseline construction plan

Based on steps 1 through 3 the alignment is di-vided into “homogeneous” regions with similarexcavation and support requirements. The base-line construction plan indicates the excavationand support methods available for each region,and contains limits and criteria for possible var-iations or modifications on site. The plan sum-marizes the geotechnical design and should con-tain following information:➮ Geological model with distribution of rock

mass types and behaviour types in a longitudi-nal section,

Fig. 2 Numericalanalysis of the rockmass behaviour for afull section (left); theinfluence of a reducedface height (centre),and the system be-haviour with installedsupport (right).Bild 2 NumerischeAnalyse des Gebirgs-verhaltens am vollenQuerschnitt (links),des Einflusses einerreduzierten Ausbruch-höhe (Mitte) sowie desSystemverhaltens mitAusbau (rechts).

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➮ Sections, where specific requirements forconstruction have to be observed,

➮ Fixed excavation and support types (roundlength, excavation sequence, overexcavation,invert distance, support quality and quantity,ground improvements, etc.),

➮ List of measures to be determined on site(support ahead of the face, face support,ground improvement, drainage),

➮ Description of system behaviour (behaviourduring excavation, deformation characteris-tics, utilization of supports),

➮ Warning criteria and levels, as well as contin-gency measures according to the safety man-agement plan.This is the final step in the geotechnical design

process. All possible geological conditionsshould be addressed with a defined range of ex-cavation and support methods as well as theprobability or likelihood of occurrence.

Step 5 – determinationof excavation classes

In the final step of the design process the geo-technical design must be transformed into a costand time estimate for the tender process. Exca-

Fig. 3 Flow chart ofbasic procedure forexcavation and sup-port selection and veri-fication of the systembehaviour during con-structionBild 3 Flussdia-gramm der grundsätz-lichen Vorgangsweisebei der Festlegung vonAusbruch und Stüt-zung und Überprüfungdes Systemverhaltenswährend des Baus.

vation classes are defined, based on the evalua-tion of the excavation and support measures.The excavation classes form a basis for compen-sation clauses in the tender documents. In Aus-tria the evaluation of excavation classes is basedon the regulations in ONORM B2203-1. In otherlocations the local or agreed upon regulationsshould be used.

The distribution of the expected behaviourtypes and the excavation classes along the align-ment of the underground structure provides thebasis for establishing the bill of quantities andthe bid price during tender.

Procedure during construction

Due to the fact, that in many cases the rock massconditions cannot be defined with the requiredaccuracy prior to construction, a continuous up-dating of the geotechnical model and an adjust-ment of excavation and support to the actualground conditions during construction is re-quired.

The final determination of excavation meth-ods, as well as support type and quantity in mostcases is possible only on site. In order to guaran-tee the required safety, a safety managementplan needs to be followed. Figure 3 shows thebasic procedure to be followed for each section.

Step 1 – determination of theencountered rock mass type

To be able to determine the encountered rockmass type, the geological investigation (documen-tation) during construction has to be targeted tocollect and record the relevant parameters thathave the greatest influence on the rock mass be-haviour (18, 19, 20). The geological and geotech-nical data collected and evaluated on site are thebasis for the extrapolation and prediction of therock mass conditions into a representative vol-ume (rock mass volume, which determines thebehaviour). In addition to recording the face con-ditions, geologists need to predict the conditionsin the volume of rock that controls the behaviour.

Predefined criteria and weighted parametersare used to identify the appropriate rock masstype.

Step 2 – determination of the actualrock mass behaviour type

Observations during excavation, such as signs ofexcessive stress, deformation pattern and ob-served failure mechanisms, and results fromprobing ahead are used to continuously updatethe geotechnical model. The reaction of theground to the excavation has to be observed, us-ing appropriate geotechnical monitoring meth-ods and layouts. Based on observations andmeasurement results during construction ashort-term prediction is made, and the actualrock mass behaviour type for the coming excava-tion step is determined (21, 22).


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Step 3 – determination of excavationand support

To determine the appropriate excavation andsupport the criteria laid out in the baseline con-struction plan have to be followed. Consequent-ly, the actual rock mass conditions (RMT, BT)continuously have to be compared to the predic-tion for compliance. A continuous detailed anal-ysis of the rock mass behaviour is used to updatethe geotechnical model. The additional data ob-tained during construction form the basis for thedetermination of the applied excavation andsupport methods. The goal is to achieve an eco-nomical and safe tunnel construction.

Based on the evaluated behaviour type, andthe excavation and support layout determinedaccording to the defined criteria, the system be-haviour for each section has to be predicted (23).

Both excavation and support, to a major ex-tent, have to be determined prior to the excava-tion. After the initial excavation only minor mod-ifications, like additional bolts, are possible. Thisfact stresses the importance of a continuousshort-term prediction.

Figure 4 shows an example for the determina-tion of excavation and support on site. To deter-mine the rock mass type, the rock type, strengthof the rock, spacing of foliation planes and slick-ensides, joint fillings and contact, thickness of cat-aclastic zones, and weathering are used. Parame-ters for the determination of the behaviour typeare the geometry of the excavation, the stressconditions, the ground water, and the relative ori-entation of discontinuities to the tunnel axis.

For the determination of the excavation andsupport two different scenarios are anticipated.In the first case no limitations in blasting vibra-tions and no restrictions in the surface settle-ments have to be observed. This allows a roundlength of 2.5 m, while for support shotcrete, rockbolts, and steel arches are used. In the secondcase the boundary conditions are different, withrestrictions both in blasting vibrations and sur-face settlements due to an adjacent building. Inthis case the round length is reduced to 1.3 m toreduce blasting vibrations and displacements. Inaddition forepoling is used to reduce loosening.This example is used to demonstrate, that differ-ent requirements strongly can influence the ex-cavation and support design.

Step 4 – verification ofsystem behaviour

By monitoring the behaviour of the excavatedand supported section the compliance with therequirements and criteria defined in the geo-technical safety management plan can bechecked. When differences between the ob-served and predicted behaviour occur, the pa-rameters and criteria used during excavation forthe determination of rock mass type and the ex-cavation and support have to be reviewed. Whenthe displacements or support utilization arehigher than predicted, a detailed investigationinto the reasons for the different system behav-iour has to be conducted, and if required im-provement measures (like increase of support)ordered (24, 25). In case the system behaviour is

Fig. 4 Example of the sequence for de-termination of excava-tion and support withdifferent requirements.Bild 4 Beispiel fürdie Bestimmung vonAusbruch und Stüt-zung bei unterschied-lichen Anforderungen.

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more favourable than expected, the reasonshave to be analysed as well, and the findingsused to better calibrate the geotechnical modeland the delimitating criteria and parameters.

Conclusion

The Guideline for the “Geomechanical Design ofUnderground Structures with Conventional Ex-cavation” of the OGG outlines a method to deter-mine support and excavation sequence for thedesign and construction of tunnels. Instead ofsupport decisions based on standardized rockmass classification systems this project tailoredprocedure incorporates the observation of therock mass behaviour and the rock mass supportinteraction in a transparent and consistent way.

There are several goals that are hoped to bereached by applying of this procedure:➮ Optimized exploratory investigation pro-

grammes by concentrating on the collection ofrock mass and project specific key parame-ters,

➮ Consistent designs meeting project specificrequirements,

➮ Optimized construction by providing clearprocedures to support the decisions on site,

➮ Continuous documentation of the decisionmaking process,

➮ Promote technical advances in tunnelling byevaluating comparable data from various sites.Most of the owners in Austria meanwhile

specify the Guideline as a basis for geomechani-cal designs. The response from owners and de-signers is very positive. The practical applicationof the Guideline has shown that a few pointsneed clarification. Currently a revision of theGuideline is under preparation, which will ap-pear later in 2003. Parallel to this, the Guidelineis translated into English, allowing a wider dis-tribution.

References1. Austrian Standards Institute: ONORM B 2203-1. 2001.2. Riedmüller, G. ; Schubert, W.: Project and rock mass spe-cific investigation for tunnels. ISRM Reg. Symp. Eurock2001, Espoo, Finland. P. Särkkä, P. Eloranta (eds.): RockMechanics a Challenge for Society, pp. 369-376. Rotterdam:Balkema, 2001.3. Bieniawski, Z.T.: Geomechanics classification of rockmasses and its application in tunnelling. Advances in rockmechanics 2(A), pp. 27-32, 1974.4. Bieniawski, Z.T.: Engineering rock mass classifications.New York: Wiley, 1989.5. Barton, N. ; Lien, R. L. ; Lunde, J.: Engineering classifica-tion of rock masses for the design of tunnel support. In: RockMechanics 6 (1974), No. 4, pp. 189-236.6. Barton, N.: NMT support concepts for tunnels in weakrocks. A. Negro Jr., A.A. Feirreira (eds.): Tunnels and Me-tropolises, pp. 273-279. Proc. intern. symp., Sao Paulo. Rot-terdam: Balkema, 1998.7. Riedmüller, G. ; Schubert, W.: Critical comments on quan-titative rock mass classifications. In: Felsbau 17 (1999),No. 3, pp. 164-167.8. Österreichische Gesellschaft für Geomechanik: Richtliniefür die Geomechanische Planung von Untertagebauarbeitenmit zyklischem Vortrieb. Salzburg, 2001.

9. Schubert, W. et al.: Method for a Consistent Determinationof Excavation and Support for Design and Construction ofTunnels. P. Särkkä, P.Eloranta (eds.): Rock mechanics; Achallenge for society, pp. 383 -388, Proc. ISRM Reg. Symp.Eurock 2001, Espoo, Finland. Rotterdam: Balkema, 2001.10. Goricki, A. ; Schubert, W. ; Steidl, A. ; Vigl, L.: Geotechni-cal Risk Assessment as the Basis for Cost Estimates in Tun-nelling. In: Felsbau 20 (2002), No. 5, pp. 24-30.11. Goricki, A. ; Schick, K.J. ; Steidl, A.: Quantification of theGeotechnical and Economic Risk in Tunnelling. Probabilis-tics in Geotechnics: Technical and Economic Risk Estima-tion. pp. 483-490, Graz, Austria, September 2002. Essen:Verlag Glueckauf GmbH, 2002.12. Hoek, E.: Putting numbers to geology – an engineer´sviewpoint. In: Felsbau 17 (1999), No. 3, pp. 139-151.13. Barton, N. ; Bandis, S.: Effects of block size on the shearbehaviour of jointed rock. Key note lecture, Proceedings 23rd

US Symposium on Rock Mechanics, Berkeley, California,pp. 739-760, 1982.14. Bhasin, R. ; Hoeg, K.: Numerical modelling of block sizeeffects and influence of joint properties in multiply jointedrock. In: Tunnelling and Underground Space Technology 13(1998), No. 2, pp. 181-188.15. Feder, G.: Zum Stabilitätsnachweis für Hohlräume in fes-tem Gebirge bei richtungsbetontem Primärdruck. In: Berg-und Hüttenmännische Monatshefte 122 (1977), No. 4, pp.131-140.16. Feder, G.: Versuchsergebnisse und analytische Ansätzezum Scherbruchmechanismus im Bereich tiefliegender Tun-nel. In: Rock Mechanics, No. 6/1978, pp. 71-102.17. Hoek, E.: Support for very weak rock associated withfaults and shear zones. Rock Support and ReinforcementPractice in Mining; Proc. intern. symp., Kalgoorlie, Australia,1999.18. Liu, Q. ; Brosch, F.-J. ; Klima, K. ; Riedmüller, G. ; Schu-bert, W.: Application of a data base system during tunnelling.In: Felsbau 17(1999), No. 1, pp. 47-50.19. Liu, Q. ; Riedmüller, G. ; Klima, K.: Quantification of pa-rameter relationships in tunnelling. P. Särkkä, P.Eloranta(eds.): Rock mechanics; A challenge for society. Proc. ISRMReg. Symp. Eurock 2001, Espoo, Finland, pp. 357 -362. Rot-terdam: Balkema, 2001.20. Gaich, A. ; Fasching, A. ; Schubert, W.: Geotechnicaldata collection supported by computer vision. ISRM Reg.Symp. Eurock 2001, Espoo, Finland. P. Särkkä, P. Eloranta(eds.): Rock Mechanics; A Challenge for Society. Proc. ISRMReg. Symp. Eurock 2001, Espoo, Finland, pp. 65-70. Rotter-dam: Balkema, 2001.21. Steindorfer, A.: Short Term Prediction of Rock Mass Be-haviour in Tunnelling by Advanced Analysis of DisplacementMonitoring Data. G. Riedmüller, W. Schubert, S. Semprich(eds.): Schriftenreihe der Gruppe Geotechnik Graz (1). Graz:Gruppe Geotechnik Graz, 1998.22. Golser, H. ; Steindorfer, A.: Displacement vector orienta-tions in tunnelling – what do they tell? In: Felsbau 18 (2000),No. 1. pp. 16-21.23. Sellner, P.: Prediction of displacements in tunnelling. G.Riedmüller, W. Schubert, S. Semprich (eds.): Schriftenreiheder Gruppe Geotechnik Graz (9). Graz: Gruppe GeotechnikGraz, 2000.24. Rokahr, R. ; Zachow, R.: Ein neues Verfahren zur tägli-chen Kontrolle der Auslastung einer Spritzbetonschale. In:Felsbau 15 (1997), No. 6, pp. 430-434.25. Hellmich, C. ; Macht, J. ; Mang, H.: Ein hybrides Verfahrenzur Bestimmung der Auslastung von Spritzbetonschalen. In:Felsbau 17 (1999), No. 5, pp. 422-425.

AuthorsUniv.-Professor Dipl.-Ing. Dr.mont. Wulf Schubert, Dipl.-Ing.Andreas Goricki, Institute for Rock Mechanics and Tunnel-ling, Graz University of Technology, Rechbauerstraße 12, A-8010 Graz, Austria, E-Mail [email protected], [email protected]; Univ.-Professor Dr. Gunter Riedmüller, Institute ofEngineering Geology and Applied Mineralogy, Graz Univer-sity of Technology, Rechbauerstraße 12, A-8010 Graz, Aus-tria, E-Mail [email protected]


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Die Publikation ist aus der Mitwir-kung der Autoren in der Forschungs-gruppe Gigawind an der UniversitätHannover – Bau- und umwelttechni-sche Aspekte von Offshore-Windener-gieanlagen – mit Unterstützung desBundesministeriums für Wirtschaftund Technologie entstanden.

von Jens Wiemann, KerstinLesny und Werner Richwien

Band 29 der Mitteilungen ausdem Fachgebiet Grundbau undBodenmechanik der UniversitätEssen, Hrsg.: Prof. Dr.-Ing.W. Richwien

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