应力途径和破裂前兆
STRESS PATH AND PRECURSORS OF RUPTURE
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摘要: 本文研究了在不同的应力途径下岩石破坏的条件和破裂的前兆.选定了三种应力途径进行研究:在一定应力状态下增加最大主应力σ1, 保持σ2, σ3不变, 使岩石破坏（A 型）;减小最小主应力使岩石破坏（B 型）;增加最小主应力岩石不破坏（C 型）.通过实验得到了济南辉长岩和昌平花岗岩 A 型途径和 B 型途径破裂强度的比较.对三种途径岩石的体应变、声发射和波速Vp, 进行了对比研究.A 型途径的破裂前兆表现与许多作者的结果相符合.B 型途径岩石断裂前处于"过密"状态, 与此相联系的声发射增加和波速Vp下降出现得很晚.C 型途径岩石处于超膨胀状态, 出现了声发射增加和波速Vp下降而岩石并未破坏的现象.Abstract: In this paper, the conditions of rupture and rapture precursors of rock samples under different stress paths have been studied. We have done some experiments by three stress paths: (1) starting from a given stress state, we increased the maximum principal stress σ1 and kept σ2 and σ3 constant until the rock sample failed (type A); (2) decreased the minimum principal stress until the rock sample failed (type B); (3) increased the minimum principal stress and kept the rock sample intact (type C). Experiments on samples of Jinan gabbro and Changping granite allow us to compare the rupture strengths for the A and B type of stress paths. Besides, we also compared the volumetric strains, acoustic emission, and velocity Vp for all three types of stress paths.For the A type, rupture precursors conform with the results of previous studies by other authors. In case B, the rock samples were in a super-dense state before rupture the related increase of acoustic emission and reduction of velocity Vp however appeared very late. In case C, the rock samples were in an over-dilatant state, increase of aeoustic emission and dropping of velocity Vp, appeared but no rupture occurred.
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