循环冲击下波阻抗定义岩石损伤变量的研究

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。

A method for defining rock damage variable by wave impedance under cyclic impact loadings

The P-wave velocities of rock with axial pre-compression cannot be measured during cyclic impacts on coupled static and dynamic test equipment,and the characteristics of rock damage evolution in the process of cyclic impacts are not able to be studied with variation of wave velocities.A method for defining damage variable of rock based on its wave impedance is proposed.Firstly,the good positive correlation between density and P-wave velocity of jointed rock was verified;and it was obtained that the variatio...