Experimental research on development of vibration excited subsidence of frozen soil under cyclic loading

Based on the constant-amplitude load tests by a new low-temperature triaxial device under realistic confining pressure, amplitudes of dynamic stress, consolidation and freezing, the residual strain behavior of frozen soil during frozen period is studied considering the influences caused by temperatures, loading amplitudes and loading cycles. The results show that the residual strain during frozen period increases with the increasing cycles of loading, but decreases with the reducing temperatures. The residual strain developing mode shows that it increases dramatically in the initial loading cycles followed by gradual increase of residual strain with time. When the dynamic stress exceeds a critical stress, the residual strain starts to increase dramatically till failure. The critical stress of frozen soil under low temperatures is larger than that under normal temperatures, with increase of 20%~25% at -5℃ and 45%~50% at -10℃. In most cases, the frozen soils tested do not fail and the residual strains under different temperatures develop nearly parallelly after certain cycles of loading. The residual strain is fairly sensitive to the frozen temperatures at large amplitudes of dynamic stress. The proposed test layout overcomes the previous testing limitations such as over consolidating pressure and over dynamic loading, so that the test results are more consistent with the real conditions.