EVALUATION OF STRENGTH CHARACTERISTICS OF COMPACTED LOESS SUBJECTED TO FREEZE-THAW CYCLING BY WAVE VELOCITY

Characterizing the mechanical properties of loess while considering the influence of freeze-thaw cycling is of great importance in geotechnical designs at Loess Plateau in China. Several key influencing factors are studied in a collective manner. They include the number of freeze-thaw cycles, the sand content, the salt content and the water content. In this paper,we carry out the unconfined compression tests,and obtain the uniaxial compressive strength of loess. At the same time,we also measure the shear wave velocity and the compression wave velocity of loess specimens subjected to different freeze-thaw cycles. The following are found: (1)the shear wave velocity and compression wave velocity decrease with an increase of freeze-thaw cycles. The reduction is more pronounced in loess samples with lower sand content. (2)The velocity of loess with high salt content decreases after the first freeze-thaw cycle,and it becomes less significant with further increase of the freeze-thaw cycles. (3)With the increase of freeze-thaw cycles and water content,the failure forms of soil samples change from brittle failure to plastic failure. (4)Based on the test results,we propose an empirical correlation between the wave velocity and the uniaxial compressive strength of loess. The research provides a new insight into evaluation of strength deterioration of loess under freeze-thaw cycle.