EXPERIMENTAL STUDY ON TRIAXIAL CONSOLIDATED UNDRAINED OF STRUCTURAL CLAYS WITH DIFFERENT BONDS AND VOID RATIOS

Laboratory and in situ tests show that some natural sedimentary clays possess strong structures, and the clay structure directly affects the calculation of ground deformation and stability. Therefore, intensively studying the mechanical characteristics of structured clays is of great engineering significance. In this study, cement and salt were added to disturbed soil samples, and Kaolin and Tianjin clay specimens with different bonding strengths and initial void ratios were artificially prepared using a compaction method. Triaxial consolidated undrained tests were conducted on structured clays with varying bond strengths and void ratios. The test results show that: (1) When the bonding strength of the specimen was relatively low and the initial void ratio was relatively high, the bonding might be damaged, and the initial void ratio might be significantly reduced during the consolidation stage. The effects of previous construction disturbance on the bonding strength and void ratio of structured clays should be considered in practical engineering. (2) The greater the bonding strength and the smaller the initial void ratio before shearing, the greater the deviator stress at the same axial strain, the higher the peak strength of the specimen, the more obvious the strain softening characteristic of the stress-strain curve, and the greater the maximum deviator stress in the stress path. (3) If the clay structure remained when the specimen reached peak strength, the stress path exhibited a structural damage stage. The Kaolin structured clays showed a tendency of shear contraction followed by shear dilation, exhibiting the phase transformation behavior of transitional soil. The Tianjin structured clays only exhibited a tendency of shear contraction. The stress path initially moved to the upper left, then to the lower left due to structural degradation.