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在动静组合加载试验系统上,对有轴向预应力的岩石进行循环冲击时无法测量其声波波速,以致于不能用声波波速值的变化研究此过程中岩石的损伤演变特性,为此提出了基于岩石波阻抗定义其损伤变量的方法。在理论上证明裂隙岩石的密度和纵波波速间具有良好的正向相关性,在同一损伤过程中,岩石的波阻抗与其纵波波速的相对变化量接近,根据密度和纵波波速都能反映岩石损伤的现实,得出基于岩石波阻抗定义岩石损伤的方法是可行的结论,并给出其定义损伤变量的表达式。根据一维应力波理论,推导出由入射波和反射波或透射波求解波阻抗的表达式。对利用霍布金森压杆装置进行试验时应力波在岩石试件两界面间多次透反射的过程进行了分析,在此基础上,确定了由试验数据计算循环冲击过程中岩石波阻抗的方法。对岩石试件进行了无初始应力的循环冲击试验,测量了岩石在每次冲击后的纵波波速,得出了基于波阻抗和纵波波速定义的损伤变量具有相同的变化趋势的结论,并分析了二者之间有差别的原因。研究结果表明,在入射能大小接近的循环冲击过程中,利用波阻抗定义岩石损伤变量的方法是可行的。
In the dynamic-static combined loading test system, the acoustic wave velocity can not be measured when the rock with axial prestressing is subjected to cyclic impact, so that the damage evolution characteristics of the rock during this process can not be studied by the change of the acoustic wave velocity value. Rock wave impedance defines the method of its damage variable. It is proved theoretically that there is a good positive correlation between the rock density and the longitudinal wave velocity. During the same damage, the rock impedance is close to the relative change of its longitudinal wave velocity. Both the density and the longitudinal wave velocity can reflect the rock damage In fact, the conclusion that rock damage is defined based on rock wave impedance is feasible and its expression of defining damage variable is given. According to one-dimensional stress wave theory, the expression of wave impedance is derived from incident wave and reflected wave or transmitted wave. Based on the analysis of the multiple transflection of stress wave between the two interfaces of rock specimen during the test with Hopkinson pressure bar device, the method of calculating the rock wave impedance in the process of cyclic impact from the test data was established . A cyclic impact test with no initial stress on the rock specimen was carried out. The longitudinal wave velocity of the rock after each impact was measured. The conclusion that the damage variables based on the wave impedance and the longitudinal wave velocity have the same trend was obtained and analyzed There is a difference between the two reasons. The results show that it is feasible to use the impedance of wave impedance to define the damage variable of rock during the cyclic impact with a large incident energy.