Energy Conservation as a Principle Underlying Mobilizable Strength Design for Deep Excavations
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 137, Issue 11
Abstract
Finite-element analyses (FEA) and case histories of deep excavations in soft clay are used to validate a decision-making tool based on an extended mobilizable strength design (MSD) method that permits the designer an extremely simple method of predicting ground displacements during an undrained excavation. This newly extended MSD approach accommodates a number of issues that are important in underground construction between in situ walls, including alternative base heave mechanisms suitable either for wide excavations in relatively shallow soft clay strata or narrow excavations in relatively deep soft strata, the influence of support system stiffness in relation to the sequence of propping of the wall, and the capability of dealing with stratified ground. In addition, a simplified MSD framework is proposed for analyzing a database of 110 deep excavation case histories worldwide. The approach examines the governing factors controlling deformation in deep excavations and offers simple guidelines for designing support structures for deep excavations. These developments should make it possible for a design engineer to make informed decisions on the relationship between prop spacing and ground movements or the influence of wall stiffness and on the need for and influence of a jet-grouted base slab, for example, prior to conducting project-specific FEA.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The writers would like to acknowledge the Platform Grant (UNSPECIFIEDGR/T18660/01) awarded by the UK Engineering and Physical Sciences Research Council. We were alerted to the extensive field records of excavations in Shanghai through a presentation by Dr. Xu of Eastern China Architectural Design and Research Institute (ECADI) at an Engineering and Physical Science Research Council (EPSRC) UK–China GEONET meeting in Ningbo in September 2008. We are grateful to Dr. Xianfeng Ma for help in translating key terms in Dr. Xu’s Ph.D. thesis.
References
Bjerrum, L., and Eide, O. (1956). “Stability of strutted excavations in clay.” Geotechnique, 6, 115–128.
Bolton, M. D., Lam, S. Y., and Osman, A. S. (2009). “Geotechnical aspects of underground construction in soft ground.” Proc., 6th Int. Symp., CRC Press, London, 15–28.
Bolton, M. D., and Powrie, W. (1987). “Behaviour of diaphragm walls retaining walls prior to collapse.” Geotechnique, 37(3), 335–353.
Bolton, M. D., Powrie, W., and Symons, I. F. (1989). “The design of stiff in-situ walls retaining overconsolidated clay part.” Ground Eng., 22(8), 44–48.
Bolton, M. D., Powrie, W., and Symons, I. F. (1990a). “The design of stiff in-situ walls retaining over-consolidated clay. Part 1: Short term behaviour.” Ground Eng., 22(9), 34–39.
Bolton, M. D., Powrie, W., and Symons, I. F. (1990b). “The design of stiff in-situ walls retaining over-consolidated clay. Part II: Long term behaviour.” Ground Eng., 23(2), 22–28.
BSI 8002. (1994). “Code of practice for earth retaining structures.” British Standards Institution, London.
Clough, G. W., and Hansen, L. A. (1981). “Clay anisotropy and braced wall behavior.” J. Geotech. Eng., 107(7), 893–913.
Clough, G. W., Smith, E. W., and Sweeney, B. P. (1989). “Movement control of excavation support system by iterative design.” Foundation engineering current principles and practices, ASCE, New York, 2, 869–882.
Eide, O., Aas, G., and Josang, T. (1972). “Special application of cast-in-place walls for tunnels in soft clay.” Proc., 5th European Conf. on Soil Mechanics and Foundation Engineering, Madrid, Spain, 1, 485–498.
Hashash, Y. M. A., and Whittle, A. J. (1996). “Ground movement prediction for deep excavations in soft clay.” J. Geotech. Eng., 122(6), 474–486.
Jen, L. C. (1998). “The design and performance of deep excavations in clay.” Ph.D. thesis, Dept. of Civil and Environmental Engineering, Massachusetts Inst. of Technology, Cambridge, MA.
Klar, A., and Osman, A. S. (2008). “Load-displacement solutions for pile and shallow foundations abased on deformation fields and energy conservation.” Geotechnique, 58(7), 581–589.
Ladd, C. C., and Foott, R. (1974). “New design procedure for stability of soft clays.” J. Geotech. Engrg. Div., 100(GT7), 763–786.
Lam, S. Y. (2010). “Ground movements due to excavation in clay: physical and analytical models.” Ph.D. thesis, Cambridge Univ., Cambridge, UK.
Long, M. (2001). “Database for retaining wall and ground movements due to deep excavations.” J. Geotech. Geoenviron. Eng., 127(3), March, 2001, 203–224.
Mana, A. I., and Clough, G. W. (1981). “Prediction of movements for braced cut in clay.” J. Geotech. Engrg. Div., 107(6), 759–777.
Milligan, G. W. E., and Bransby, P. L. (1976). “Combined active and passive rotational failure of a retaining wall in sand.” Geotechnique, 26(3), 473–494.
Moormann, C. (2004). “Analysis of wall and ground movements due to deep excavations in soft soil based on a new worldwide database.” Soils Found., 44(1), 87–98.
O’Rourke, T. D. (1993). “Base stability and ground movement prediction for excavations in soft clay.” Retaining structures, Thomas Telford, London, 131–139.
Osman, A. S., and Bolton, M. D. (2004). “A new design method for retaining walls in clay.” Can. Geotech. J., 41(3), 451–466.
Osman, A. S., and Bolton, M. D. (2005). “Simple plasticity-based prediction of the undrained settlement of shallow circular foundations on clay.” Geotechnique, 55(6), 435–447.
Osman, A. S., and Bolton, M. D. (2006). “Ground movement predictions for braced excavations in undrained clay.” J. Geotech. Geoenviron. Eng., 132(4), 465–477.
Osman, A. S., Bolton, M. D., and Mair, R. J. (2006). “Predicting 2D ground movements around tunnels in undrained clay.” Geotechnique, 56(9), 597–604.
Roscoe, K. H., and Burland, J. B. (1968). “On the generalized stress-strain behaviour of ‘wet’ clay.” Engineering plasticity, J. Heyman and F. A. Leckie, eds., Cambridge University Press, Cambridge, UK.
Skempton, A. W. (1951). “The bearing capacity of clays.” Proc., Building Research Congress, London, 180–189.
Sloan, S. W. (1988). “Lower bound limit analysis using finite elements and linear programming.” Int. J. Numer. Anal. Methods Geomech., 12(1), 61–77.
Sloan, S. W., and Kleeman, P. W. (1995). “Upper bound limit analysis using discontinuous velocity fields.” Comput. Methods Appl. Mech. Eng., 127, 293–314.
Terzaghi, K. (1943). Theoretical soil mechanics, Wiley, New York.
Ukritchon, B., Whittle, A. J., and Sloan, S. W.(2003). “Undrained stability of braced excavations in clay.” J. Geotech. Geoenviron. Eng., 129(8), 738–755.
Whittle, A. J. (1987). “A constitutive model for overconsolidated clays with application to the cyclic loading of friction piles.” Ph.D. thesis, Dept. of Civil and Environmental Engineering, Massachusetts Inst. of Technology, Cambridge, MA
Whittle, A. J. (1993). “Evaluation of a constitutive model for overconsolidated clays.” Geotechnique, 43(2), 289–313.
Information & Authors
Information
Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 137 • Issue 11 • November 2011
Pages: 1062 - 1074
Copyright
© 2011 American Society of Civil Engineers.
History
Received: Aug 24, 2009
Accepted: Jan 14, 2011
Published online: Jan 17, 2011
Published in print: Nov 1, 2011
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.