强地震动作用下层状岩体破坏的物理模拟研究

Physical simulation study on dynamic failures of layerad rock masses under strong ground motion

岩体地震动力破坏现象是常见但研究较少的复杂课题。利用物理模拟试验,研究了层状岩体边坡在强地震动作用下的变形破坏问题。按结构面走向平行和垂直地震动方向,对不同岩体结构特征的模型施加不同的幅值和频率的水平向地震动荷载,进行岩体的振动破坏试验。结果表明,结构面空间展布方向与地震动荷载的相互关系不同、结构面软弱程度不同,岩体变形破坏的形式和分布特征也不相同。岩体的动力破坏主要是岩体结构的破坏,即岩体结构的宏观破坏和微观损伤,岩体结构特征是控制其动力变形破坏的主要因素。极大的不均匀性是岩体动力破坏的显著特点,这与大量极震区岩体破坏的现象类似。但岩体动力破坏模式的建立和定量的力学分析还需更多研究。

Dynamic failures of rock masses under strong ground motion are common phenomena usually observed but lack of studies because of their complexity. Deformation failures of layered rock masses under strong ground motion are studied by physical simulation experiments. Horizontal ground motion with different amplitudes and frequencies is respectively operated on models with different structure characteristics to investigate dynamic failure of layered rock masses according to mutual relation between discontinuity orientations and seismic forces. The results indicate that deformation failures of rock masses have different forms and distributing characteristics because of different spatial relations between discontinuities and dynamic forces and different discontinuities strengths. Structure failure of rock mass is principal that can be classified into macroscopical failure and microcosmic damage, structure characteristics of rock mass is dominating factor of dynamic failure of rock mass; inhomogeneity is one of its outstanding characteristics that are similar with those of the rock mass suffered from strong ground motions at meizoseismal areas. More researches are badly needed to establish dynamic failure modes of rock mass and to carry out quantitative mechanical analysis.