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通过富水砂质泥岩循环三轴试验,对循环荷载作用下砂质泥岩的动应变发展规律进行了研究,重点分析了动应力水平、静偏应力大小以及振动频率对动应变的影响。结果表明:富水砂质泥岩在循环荷载作用下的不可逆应变累积过程表现为稳定型和破坏型两种典型情况。对于稳定型发展曲线,变形发展表现为初始阶段和稳定阶段,初始阶段的累积变形约占总变形量的40%～50%,但所占比重随着应力水平的提高逐渐减小;对于破坏型发展曲线,变形发展表现为初始阶段、稳定阶段和加速阶段的三阶段变形演化规律。岩样的累积塑性变形随动应力和静偏应力的提高而增大,随振动频率的增大而减小,而且动应力和静偏应力越大,变化趋势越明显。富水砂质泥岩的临界动应力值与其岩性、应力水平、振动频率等密切相关。
Through the cyclic triaxial tests of sandy silt rich in water, the law of dynamic strain development of sandy mudstone under cyclic loading was studied. The effect of dynamic stress level, the magnitude of static deviatoric stress and vibration frequency on dynamic strain were analyzed emphatically. The results show that the irreversible strain accumulation process of sandy silt rich in water under cyclic loading is characterized by two typical cases: steady state and failure state. For the stable development curve, the deformation development shows the initial stage and the steady stage. The cumulative deformation in the initial stage accounts for 40% ~ 50% of the total deformation, but the proportion decreases gradually with the increase of the stress level. Development curve, deformation development performance of the initial stage, the steady stage and acceleration stage of the three stages of deformation and evolution. The cumulative plastic deformation of rock samples increases with the increase of dynamic stress and static deviatoric stress and decreases with the increase of vibration frequency. The greater the dynamic stress and static deviatoric stress, the more obvious the change trend. The critical dynamic stress value of sandy silt is closely related to lithology, stress level and vibration frequency.