EXPERIMENTAL STUDY ON DYNAMIC FAILURE CHARACTERISTICS OF LOESS SLOPE WITH BEDROCK AND OVERBURDEN LAYER BY LARGE SCALE SHAKING TABLE TEST

To study the relationship between dynamic failure characteristics and acceleration response of loess-covered slopes,a 1∶20 shaking table test is set up. The amplitude of the input seismic wave is gradually increased. The development law of slope cracks in the whole cycle is tested in real time during the test. The MATLAB dynamic failure feature detection system is used to obtain the basic information of the surface cracks. The dynamic failure features of the slope surface are proposed. The peak acceleration change law of the monitoring points of each working condition is also analyzed. The results are as follows: (1)The crack width and crack area of the slope top and toe have a jumping growth when the input peak acceleration is 0.6g,indicating that the soil at the soil-rock contact surface has undergone progressive shear failure. The acceleration peak response on the sliding surface and the slope surface has a sudden significant change,indicating that the slope has been damaged. (2)The acceleration magnification coefficients along both the slope and sliding surfaces increase non-linearly. Additionally,the magnification coefficients along the slope surface are obviously larger than those along the sliding surface under various working conditions,indicating that the acceleration magnification effect along the elevation is obvious. (3)The sudden increase of tensile and shear cracks area is an important feature of slope failure. The generation of through cracks and the sudden change of acceleration response can be used as the basis for slope dynamic failure. Furthermore,the generation of through cracks and the sudden change of acceleration response can be used as the basis for the dynamic failure of the slope.