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为研究受载过程中特别是循环加卸载作用下岩石电阻率变化规律,对单轴等幅循环加卸载和分级循环加卸载条件下岩石破坏过程中的电阻率响应特征进行研究。试验结果表明,岩石电阻率变化与荷载变化或试件内微裂隙发展密切相关。等幅循环加卸载过程中,加载时随着荷载的增加,岩石的电阻率总体上呈下降的变化趋势;第1次加载循环与其他4次加载循环明显不同,在加载初期存在快速下降阶段;卸载时,试样电阻率会逐渐恢复;5次加载循环中,完全卸载(载荷0 k N)和完全加载(载荷40 k N)时,不同循环电阻率不同,第一次最大,以后逐次减小。分级循环加卸载与等幅循环加卸载存在一些相同的规律,不同之处在于:5次加载循环中,完全卸载(载荷0 k N)和完全加载(载荷取第一级完全加载时荷载35 k N)时,不同循环电阻率也不同,前3次循环电阻率依次减小,后2次循环逐次略有增加;破坏加载时,加载初期也存在快速下降阶段。对2种循环加卸载过程中电阻率变化规律采用循环加载下微裂隙闭合机制进行了解释。试验研究表明,电阻率变化可以较好地表征单轴等幅循环加卸载和分级循环加卸载过程中试件内微裂隙发展情况。
In order to study the variation law of resistivity of rock under loading and unloading, especially the cyclic resistivity of rock under loading and unloading unloading and grading cyclic loading and unloading, the resistivity response characteristics during rock failure were studied. The experimental results show that the change of rock resistivity is closely related to the change of load or the development of micro-cracks in the specimen. During the loading and unloading process, the resistivity of rock decreases with the increase of load. The first loading cycle is obviously different from the other four loading cycles, and there is a rapid decline in the initial loading period. When unloading, the resistivity of the sample will gradually recover. In 5 loading cycles, the total resistivity of different cycles is different after unloading (load 0 kN) and full loading (load 40 kN) small. Hierarchical cyclic loading and unloading and constant amplitude cyclic loading and unloading there are some of the same rules, except that: 5 times the loading cycle, complete unloading (load 0 kN) and fully loaded (first load full load load 35 k N), the resistivity of different cycles is also different, the resistivity of the first three cycles decreases in turn, and the second cycle increases slightly after one cycle. At the time of destructive loading, there is also a rapid descent phase. The law of resistivity change during loading and unloading of two kinds of cycles was explained by the mechanism of microcrack closure under cyclic loading. Experimental results show that the change of resistivity can well characterize the development of microcracks in specimens during loading and unloading with uniaxial cyclic loading and unloading cycles.