Collapsible Loess Static Characteristics And Ct Scan Of The Triaxial Test Process

The compression test and triaxial test of the original loess and remolded loess are carried out. The influence of the structure strength of the original loess to its collapsibility and the triaxial damage form is analyzed. Discrimination of the original loess and disturbed loess is compared and explained. To analyze the loess characters of compression, collapsibility and expansion after unloading, water content and the compaction degree of the loess is changed in the test which indicates that the loess with high compaction degree and low water content still has collapsibility. The cause of its expansion is explained by hydrology characteristic of clay soil , damage process caused from expansion is exposed subsequently.The triaxial shear test of the original loess is carried out and the CT scanning is ongoing at the same time. Combining images and data of the CT scanning with the stress-strain curve, the course of soften dehiscence damage and harden yield damage is explained by means of damage theory. Determination method of the damage threshold stress and damage threshold strain is given, six kinds of damage variables (which are across isotropy effectual elastic modulus damage variable, simple effectual elastic modulus damage variable, density damage variable, volume damage variable, volume density damage variable and area density damage variable) are defined, evolution curves and evolution equations of harden yield damage are obtained. The CT scanning is ongoing when collapsibility test under triaxial condition of the original loess is conducted. Based on combination triaxial collapsibility images with data of scanning, transformation of the microstructure of loess and the mechanism of collapsibility is made clear.