Abstract:

Triaxial consolidation undrained shear tests were performed on both undisturbed and remolded samples of soft Lianyungang clay to investigate its undrained shear strength behavior. The test results indicated that the strength envelope of the undisturbed sample is composed by two straight lines separated by the triaxial consolidation yield stress. The strength envelopes of remolded samples, however, are straight lines through the origin. When the applied confining stress is less than the triaxial consolidation yield stress (i.e. pre-yield stress state), undrained shear strength of undisturbed samples are larger than remolded samples due to the resistance of soil structure. While at post-yield state (the applied confining stress is larger than the triaxial consolidation yield stress), strength envelope of the undisturbed sample lies among the remolded samples with different initial water contents. This difference is found to be caused by the difference in initial water content. The changing in water content and strength with confining stress for undisturbed sample at post-yield state behave like as a remolded sample at given initial water content. The compression behavior of undisturbed sample at post-yield state or remolded samples of different initial water contents can be well normalized by the void index proposed by Burland.

Key words: undisturbed samples, remolded samples, undrained shear strength, initial water content