Experimental study on effects of heating-cooling cycles on shear characteristics of clay

The consolidated undrained shear tests on the normally consolidated saturated clay after heating-cooling are carried out by using the temperature-controlled triaxial apparatus. The effects of the heating-cooling on the soil strength, effective stress path and excess pore pressure are studied. The results show that under the confining pressures of 100, 200, 400 kPa, the soil samples exhibit similar characteristics to those of the overconsolidated soil after heating-cooling, and the consolidated undrained shear strength increases by 25.8%, 22.1% and 14.8%, respectively. The change of strength mainly shows the improvement of cohesion, and the critical friction angle basically remains unchanged. By comparing the consolidated undrained shear test results of the soil samples with different OCRs at room temperature, it is found that the peak strength of the soil samples after heating-cooling is similar to that when OCR=1.5, but the increment of plastic volumetric strain generated during heating-cooling is much smaller than that generated by mechanical loading and unloading, which indicates that the hardening effects of heating-cooling on soil are different from the volumetric hardening mechanism of the overconsolidated soil.