Compression and extension yield of an anisotropically consolidated soil

A series of undrained and drained triaxial tests were conducted to investigate the yielding behavior of anisotropically consolidated reconstituted Shanghai clay under triaxial compression and extension loading conditions. The soil was consolidated with K of 0.5, where K is the ratio of cell pressure to axial pressure. The tests included drained constant η (=q/p′) loading tests and undrained and drained triaxial compression and extension shear tests on anisotropically consolidated specimens. It was found that the anisotropically consolidated Shanghai clay obeys Rendulic’s principle under compression loading, but not under extension loading, and that the yield surface inclined inside the state boundary surface under extension loading. Moreover, the pre-yield behavior and the post-yield behavior were found to be very different under these two loading conditions (compression and extension loading). The test results confirm the validity of the sloping elastic wall theory, and the influence of anisotropic parameter β on the shape of the yield curve in the p′?v plane was also studied in the paper. Constitutive modeling methods for anisotropic consolidated soils were also discussed based on the test results.