Mechanisms of Load Transfer and Arching for Braced Excavations in Clay
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 128, Issue 3
Abstract
This paper presents a detailed interpretation of the evolution of stresses around a braced excavation in a deep layer of soft clay. Excavation support is provided by a diaphragm wall and multiple levels of rigid cross-lot bracing. Undrained shearing of the clay is represented by an advanced effective stress soil model that simulates important features of behavior including anisotropic stress-strain-strength relationships, small strain nonlinearity, and hysteretic response upon load reversal. The results provide new insight for explaining the development of lateral earth pressures for braced excavations and give a quantitative illustration of conceptual load transfer mechanisms and soil arching discussed previously in the literature. Reversals in the direction of shearing occur when the upper retained soil is squeezed against the bracing by deep-seated incremental movements in the soil mass, and arching of stresses below the lowest level of bracing. These mechanisms apply for a wide range of soil profiles when the wall is not keyed into an underlying bearing layer. Field measurements from an instrumented project in Taiwan lend credibility to the stress paths predicted in these numerical experiments.
Get full access to this article
View all available purchase options and get full access to this article.
References
Aas, G. (1984). “Stability problems in a deep excavation in clay.” Proc., Int. Conf. Case Histories in Geotechnical Engineering, Vol. 1, Univ. of Missouri–Rolla, Rolla, Mo., 315–323.
Borin, D. L. (1989). WALLAP—computer program for the stability analysis of retaining walls, Geosolve, London.
Brinkgreve, R. B. J., and Vermeer, P. A. (1998). Plaxis—version 7 users manual, Balkema, Rotterdam, The Netherlands.
Britto, A. M., and Gunn, M. J. (1987). Critical state soil mechanics via finite elements, Halsted, Chichester.
Cundall, P., and Board, M. (1988). “A microcomputer program for modeling large-strain plasticity problems.” Proc., 6th Int. Conf. Numerical Methods in Geomechanics, Balkema, Rotterdam, 2101–2108.
Goldberg, D. T., Jaworski, W. E., and Gordon, M. D. (1976). “Lateral support systems and underpinning.” Rep. FHWA-RD-75-128, Federal Highway Administration, Washington, D.C.
Hashash, Y. M. A. (1992). “Analysis of deep excavations in clay.” PhD thesis, MIT, Cambridge, Mass.
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.
Konstantakos, D. (2000). “Measured performance of slurry walls.” SM thesis, MIT, Cambridge, Mass.
Lambe, T. W. (1970). “Braced excavations.” Proc., Specialty Conf. Lateral Stresses in the Ground and Design of Earth Retaining Structures, ASCE, New York, 149–218.
Lambe, T. W., and Whitman, R. V. (1969). Soil mechanics, Wiley, New York.
Liao, S. S. C., and Neff, T. L. (1990). “Estimating lateral earth pressures for design of excavation support.” Proc., ASCE Specialty Conf. on Design and Performance of Earth Retaining Structures, ASCE, New York, 489–509.
Moh, Z.-C., and Chin, C.-T. (1991). “Deep excavation in soft ground.” Proc., 2nd Int. Conf. on Construction: New Frontiers, Moh and Associates, Singapore.
Ng, C. W. W.(1999). “Stress paths in relation to deep excavations.” J. Geotech. Geoenviron. Eng., 125(5), 357–363.
Ng, C. W. W., and Yan, R. W. M.(1998). “Stress transfer and deformation mechanisms of diaphragm wall panel.” J. Geotech. Geoenviron. Eng., 124(7), 638–648.
O’Rourke, T. D., McGinn, A. J., Dewsnap, J., and Stewart, H. E. (1997). “Performance of excavations stabilized by deep soil mixing.” Research Rep. submitted to Bechtel/Parsons Brinckerhoff, Cornell Univ., Ithaca, N.Y.
Pappin, J. W., Simpson, B., Felton, P. J., and Raison, C. (1985) “Numerical analysis of flexible retaining walls,” Proc., Numerical Methods in Engineering Theory and Applications (NUMETA’85), Balkema, Rotterdam, 789–802.
Peck, R. B. (1969). “Deep excavations and tunneling in soft ground.” Proc., 7th Int. Conf. Soil Mechanics and Foundation Engineering, International Society of Soil Mechanics and Foundation Eng., Mexico City, 225–290.
Poh, T. Y., and Wong, I. H.(1998). “Effects of construction of diaphragm wall panels on adjacent ground: Field trial.” J. Geotech. Geoenviron. Eng., 124(8), 749–756.
Roscoe, K. H., and Burland, J. B. (1968). “On the generalised stress-strain behavior of ‘Wet’ clay.” Engineering plasticity, J. Heyman and F. A. Leckie, eds., Cambridge University Press, Cambridge, England, 535–609.
Seah, T. H. (1990). “Anisotropy of normally consolidated Boston Blue Clay.” ScD thesis, MIT, Cambridge, Mass.
Whittle, A. J.(1993). “Evaluation of a constitutive model for overconsolidated clays.” Geotechnique, 43(2), 289–313.
Whittle, A. J., DeGroot, D. J., Ladd, C. C., and Seah, T.-H.(1994). “Model prediction of anisotropic behavior of Boston Blue Clay.” J. Geotech. Eng., 120(1), 199–224.
Whittle, A. J., and Hashash, Y. M. A. (1994). “Soil modeling and prediction of deep excavation behavior.” Proc., Int. Symposium on Pre-Failure Deformation Characteristics of Geo-Materials (IS-Hokkaido’94), Vol. 1, Balkema, Rotterdam, The Netherlands, 589–595.
Whittle, A. J., Hashash, Y. M. A., and Ladd, C. C. (1993). “Analysis of excavation in Taipei.” MIT Research Rep. R93-12, Dept. of Civil Engineering, MIT, Cambridge, Mass.
Whittle, A. J., and Kavvadas, M. J.(1994). “Formulation of MIT-E3 constitutive model for overconsolidated clays.” J. Geotech. Eng., 120(1), 173–198.
Woo, S.-M., and Moh, Z.-C. (1990). “Geotechnical characteristics of soils in the Taipei basin.” Proc., 10th Southeast Asian Geotechnical Conf., Southeast Asian Geotechnical Society, Bangkok, Thailand, 1–26.
Information & Authors
Information
Published In
Copyright
Copyright © 2002 American Society of Civil Engineers.
History
Received: Mar 3, 2000
Accepted: Aug 20, 2001
Published online: Mar 1, 2002
Published in print: Mar 2002
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.