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对取自陕北榆横矿区小纪汗煤矿顶板砂岩的干燥及饱和试件进行单轴循环加、卸载试验,分析了干燥与饱和状态下岩石的强度和变形特征以及岩石破坏过程中的能量演化与能量分配情况。结果表明:(1)循环加、卸载导致干燥试件的峰值强度较单轴压缩时下降19.47%;(2)饱水对砂岩的强度和变形均有影响,饱和试件的平均峰值强度比干燥试件低39.55%,同时饱和试件具有更加明显的压密阶段;(3)循环加、卸载下砂岩的加载和卸载弹性模量均呈现增大趋势,但饱和试件的弹性模量低于干燥试件;(4)通过峰值强度归一化处理后发现,在应力加载的不同阶段,饱和试件的弹性应变能Ue和耗散能Ud均低于干燥试件;(5)加载过程中,饱和试件弹性应变能Ue的占比高于干燥试件,该比例随着加载过程逐渐下降并在破坏前与干燥试件的Ue的占比达到近似水平。
Uniaxial cyclic loading and unloading tests were carried out on the dry and saturated specimens taken from the sandstone of the Xiajian Coal Mine in the Yulian mining area of northern Shaanxi Province. The strength and deformation characteristics of rock under dry and saturated conditions and the energy evolution during rock failure were analyzed And energy distribution. The results show that: (1) The peak strength of dry specimens decreased by 19.47% compared with that under uniaxial compression due to cyclic loading and unloading; (2) The saturated water had an impact on the strength and deformation of sandstone, and the average peak intensity of saturated specimens was lower than that of dry specimens (3) The loading and unloading elastic modulus of sandstone under cyclic loading and unloading all showed an increasing trend, but the elastic modulus of saturated specimen was lower than that of saturated specimen (4) After normalized by the peak intensity, it is found that the elastic strain energy Ue and the dissipation energy Ud of the saturated specimen are lower than that of the dry specimen at different stages of stress loading. (5) During the loading process , The proportion of the elastic strain energy Ue of the saturated specimen is higher than that of the dry specimen, which gradually decreases with the loading process and reaches the approximate level of the Ue of the dry specimen before failure.