爆炸与冲击中的非线性岩石力学问题(Ⅱ):冲击扰动诱发岩块滑移的物理模拟试验

Nonlinear mechanical problems in rock explosion and shock. Part Ⅱ:Physical model test on sliding of rock blocks triggered by external disturbance

深部岩体为具有块状层次结构的含能地质体,在冲击扰动通过块系岩体向前传播的振动过程中,极易诱发原先处于平衡状态的岩体的内应力释放,产生不可逆变形、岩爆、工程地震等工程灾害。利用自行研制的块系岩体动态力学性能测试试验系统,进行不同初应力条件下冲击扰动诱发岩块滑移的物理模拟试验,获得冲击扰动诱发岩块不可逆位移、动力滑移失稳的关键力学机制、规律及充分必要条件。通过深入研究冲击扰动下初应力岩体运动的能量转化机制,推导得到了支配岩块运动规律的特征能量因子,给出了与不同规模的岩体破坏(不可逆位移、动力滑移失稳)相适应的特征能量因子阈值和判别准则。研究表明,基于特征能量因子的判别准则能较好的表征冲击扰动诱发岩块间不可逆位移和动力失稳的特征科学现象。

Rock masses can be regarded as the hierarchical structure of masses composed of blocks with structural planes and have the capability of storing energy at micro-level.Propagation of stress waves in rock masses generated by the external disturbances may trigger the release of internal energy and result in geologic hazards such as very large irreversible deformation,rockburst,engineering earthquake and so on.With the dynamic testing system of rock blocks developed in-house,the physical experiments to simulate the slipping of rock blocks induced by the impact disturbances were carried out to study the mechanism of irreversible displacements and slip failure,the influence factors and the conditions of threshold energy.Experimental results show that when the initial shear force is close to zero,the irreversible displacement may be induced by the external disturbances.The threshold energy of the irreversible displacement decreases with the increase of the initial shear force.When the initial shear force is close to the dynamic shear strength,the external disturbances may trigger slip failure.A dimensionless characteristic energy factor was used to characterize the threshold energy conditions of the irreversible displacement and slip failures induced by external disturbances.The physical relationship between the characteristic energy factor and the dimensionless energy conditions for pendulum-type waves was discussed.The comparison with experimental results shows that the energy factor can characterize the threshold energy conditions of irreversible displacements and slip failures induced by the external disturbances very well.