Study On The Tests And Application Of Shear Band Deformation Of Soft Clay

When practical engineering was designed, it had satisfied the norms and had somesecurity reserve, but the damage of deep foundation pits and high embankments occurredoccasionally, because the research of localization was not enough. During a long time,it was little understanding of the shear band, and the research of shear band was asphenomenon description only. In order to research the shear band phenomenon deeply, aseries of plane strain compression tests and triaxial tests of Shanghai muddy slity clay,were carried on. Most of the sample's response was recorded during the shearingprocedure, such as the stress-strain response, the development of pore water pressure,and the evolution of local lateral non-homogeneous deformation. Based on theexperimental results analysis, conclusions were gotten: 1) The el of shear bandbeginning was equal to theε₁ of yield of strain-stress curves. That showed theformation of shear band was caused by pore pressure; 2) Theε₁ of yield point ofShanghai muddy slity clay was same whatever in plane strain tests or in triaxial tests;3) The feature points could get from the pore pressure-strain curves, and they havesome identified relationship. Based on the experimental results, the soften modelconsidering the shear band deformation of Shanghai muddy silty clay was gotten. Thedevelopment of shear band was simulated with FEM program and FDM program,adopting the model considering the shear band deformation. The simulation resultsshowed that the development of shear band accorded with the factors such asdilytancy angle, initial damage, constitutive model and boundary conditions. In orderto reduce the accidence of engineering, the method that adopt the strengthen index ofshear band beginning as design parameter was suggested in this article. It showed thatthe method considering the localization in this article could calculate the deformationof deep foundation pit with two examples of deep foundation pit in Shanghai.Because of the factors such as test conditions limit, the research job of shear band wasa little done, more jobs should be carried on for the future research.