Damage and pressure melting analysis of frozen saline soils in process of triaxial compression tests

The mechanical properties, such as damage and pressure melting, have significant influences on the strength and deformation behaviors of the frozen saline soils in the process of triaxial compression tests. In order to analyze the change laws of damage evolution and pressure melting variation, a series of triaxial shear loading-unloading-reloading tests and CT scanning tests are carried out for Delhi frozen saline soils at -15℃. The results show that the damage variable is influenced by hydrostatic pressure. When the hydrostatic pressure is between 1 MPa and 12 MPa, the damage variable increases with pressure, and when hydrostatic pressure is more than 12 MPa, with the increase of the hydrostatic pressure, the damage variable shows a decreasing trend. Meanwhile, the definitions of pressure melting threshold${{p}_{\text{s}}}$and the corresponding hydrostatic pressure value${{p}_{\text{m}}}$when the pressure melting variable reaches the maximum value are given. The pressure melting is hardly existent in the sample when pressure is less than the threshold. When the pressure is between${{p}_{\text{s}}}$and${{p}_{\text{m}}}$, the pressure melting variables can be expressed by the parabola equation. And if the hydrostatic pressure exceeds${{p}_{\text{m}}}$, the pressure melting variable reaches the maximum value${{\lambda }_{\text{m}}}$. Besides, the hydrostatic pressure corresponding to the maximum value of the pressure melting variables almost equals the hydrostatic pressure when the damage variable gets its maximum.