Abstract: Early in the 60s-70s of the 20th century, Japanese and American scientists have successfully observed the variation of gravity associated with earthquake process. In China, many researchers have studied the gravity field of some typical earthquakes. The results showed that observable variations of gravity do exist during the development process of medium-strong earthquakes, and that different earthquakes have different features of gravity variation. It is considered that the density variation in the crust may be an important factor. In this paper a model of stress-failure coupling effect is proposed in the light of failure mechanism. In addition, the theoretical relation between the stress failure coupling effect and variation of gravity in the crust is derived according to strain equivalent hypothesis. Furthermore, the different features of gravity evolution during the development processes of the Tangshan earthquake (M_S7.8) in 1976 and the Kunlun earthquake (M_S8.1) in 2001 are simulated through rock mechanical test with various loading paths. The results are something in good agreement with the actual facts and show that the stress failure coupling effect may be a physical explanation of gravity change before earthquake.

Key words: stress-failure, coupling effect, gravity variation

摘要： 文中运用损伤力学研究方法,提出孕震过程中引起地壳破坏的应力-损伤耦合效应。利用应变等效性假设,推导了地壳体的应力-损伤耦合效应与地表重力变化之间的理论关系。根据岩石力学实验的不同加载途径,模拟了1976年唐山7.8级地震和2001年昆仑山口西8.1级地震重力演化的不同特征,结果与实际情况符合较好,表明应力-损伤耦合效应可以作为地震前地壳重力变化的一种物理解释。

关键词: 应力, 损伤, 耦合效应, 重力变化