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岩石变形特征与所受的应力状态以及加载历史密切相关.基于三轴循环加卸荷试验,研究了不同围压、不同应力状态、不同卸荷量对砂岩变形特征及参数的影响.试验结果表明,卸荷过程中岩石变形模量变化规律和加载时并不相同:①相同应力差下,围压越大,相同卸荷量引起的变形模量降低量越小;②相同的围压下,应力差越大,相同卸荷量引起岩样变形模量的降低值越大;③循环荷载在岩石极限强度30%以内时,完全卸荷后岩石变形模量降低30%左右;循环荷载为岩石极限强度的30%～100%时,完全卸荷后岩石变形模量降低30%～60%左右;④不同围压下,卸荷时岩石变形模量降低量和卸荷量呈很好的线性关系.
The deformation characteristics of rock are closely related to the stress state and loading history.Based on the triaxial cyclic loading and unloading test, the effects of different confining pressure, different stress states and different unloading amount on the deformation characteristics and parameters of sandstone are studied.The results show that , The law of rock deformation modulus change during unloading is different from that under loading: (1) Under the same stress difference, the larger the confining pressure, the smaller the decrease of deformation modulus caused by the same unloading; (2) Under the same confining pressure, The larger the stress difference, the greater the decrease of the deformation modulus of the rock specimen caused by the same unloading amount. (3) When the cyclic loading is within 30% of the rock ultimate strength, the rock deformation modulus decreases by 30% after complete unloading; the cyclic loading is rock When the ultimate strength is between 30% and 100%, the deformation modulus of rock after complete unloading is reduced by about 30% -60%. (4) Under different confining pressure, there is a good linearity relationship.