三轴压缩岩石动静组合强度及变形特征的研究

Static-dynamic coupling strength and deformation characteristics of rock under triaxial compression

为研究深部地下资源开发过程中矿岩的力学行为,利用自行研制的岩石动静组合加载试验机,对细砂岩进行了两个系列的三维动静组合加载试验,即固定围压改变轴向静压和固定轴向静压改变围压的试验,并对实验数据整理分析。试验结果表明:围压不变时,细砂岩动静组合强度、弹性模量随轴向静压增大先升高(弹性阶段)后降低(损伤阶段);最大应变率和平均应变率则先下降后升高,并且当轴向静压在其静态三轴抗压强度80%左右时,动静组合强度最大;轴向静压不变时,增大围压,细砂岩动静组合强度、弹性模量升高,平均应变率下降,而最大应变率的变化趋势无明显规律。

By means of the improved SHPB with axial pre-pressure and confined pressure, a series of experiments on sandstone are carded out to research the mechanical behaviors of rock during the course of exploitation of resources in deep. The experiment includes some tests under triaxial static-dynamic coupling loads with fixed confined pressure or fixed axial static pressure. The results from tests under fixed confined pressure show that both static-dynamic coupling strength and elastic modulus are increased at the elastic stage and decreased at failure stage with increasing axial static pressure. The maximal strain rate and average strain rate are decreased at the elastic stage and increased at failure stage. When the axial static stress reaches to 80% of the corresponding static triaxial compressive strength, the static-dynamic coupling strength will be up to the maximum. On the condition of fixed axial static pressure, the static-dynamic coupling strength and elastic modulus are increased and the average strain rate is decreased with increasing confined pressure. It is found that the maximal strain rate is not obvious related with the confined pressure.