水对断层摩擦滑动稳定性的影响  

THE EFFECT OF WATER ON STABILITY OF FRICTIONAL SLIDING OF FAULT

作　　者：黄建国[1] 张流[1] 

机构地区：[1]中国地震局地质研究所,北京100029

出　　处：《地震地质》2002年第3期387-399,共13页Seismology and Geology

基　　金：.NULL.

摘　　要：在不同含水条件下研究了光面、含脆性物质夹层和含延性物质夹层 3类断层的摩擦滑动行为 ,认为水对断层滑动稳定性和摩擦滑动的速度依赖性有重要影响。建立了含有岩性、围压 (深度 )和含水量 3因素的断层活动稳定性的模式 ,认为脆性断层更多地表现为速度弱化 ,少量水的存在易于出现黏滑 ,高孔隙压时会表现为稳滑 ;半脆性或半延性的断层在少量水或较低孔隙压的情况下会表现出速度弱化 ,也就可能出现黏滑 ,但孔隙压较高后 ,会表现出速度强化 ,滑动也就会是稳定的 ;延性断层多为速度强化 ,不出现黏滑。提出水的进入降低了系统的稳定性 ,水的存在增加了系统的稳定性。这是考虑水或一般流体对岩体或断层活动稳定性影响时需要考虑的两个方面。The friction behavior of faulted granite samples, with size of Φ 20 mm×40mm and saw cut at an angle of 35° to σ 1 axis, was experimentally studied under various water containing conditions and tri axial compression. The stability during stable sliding or stick slip was emphasized. Three types of polished fault surface are considered: (1) two surfaces contact directly without any gouge in between, used to simulate the friction behavior of brittle fault; (2) the preset fault is filled with 0 25g quartz powder with mean grain size of 10μm, used to simulate the friction behavior of a fault containing brittle gouge; (3) the preset fault is filled with 0.25g clay fault gouge with grain size of <10μm, used to simulate the friction behavior of a fault containing ductile gouge. The water content ranges from dry to water saturated, and the pore pressure ranges from 20 to 150MPa. The following conclusions can be drawn from the results of the experiment: (1) The mode of faulting is strongly influenced by the existence of water. For dry polished surfaces without any gouge, there is a certain range of confining pressure in which stick slip behavior exists. This range of confining pressure may shrink quickly when water enters and forms pore pressure on sliding surface, i.e. the friction behavior turn to stable sliding. For samples with quartz powder, frictional behavior changes from stable sliding to stick slip when dry gouge becomes wet, and return to stable sliding again when gouge is saturated and undrained. In this case, there exists also a certain range of confining pressure in which stick slip behavior exists. For samples with clay gouge, frictional sliding keeps stable under any humidity and pore water pressure. (2) Experimental study also shows that stress drop of stick slip is dependent on the water content. For samples without gouge, stress drop decreases with increasing water content in rock. For samples with quartz powder gouge, however, stress drop increases quickly at first and then slo

关 键 词：摩擦滑动 断层活动 稳定性 水 发震原因 岩性 围压 含水量 

分 类 号：P315.1[天文地球—地震学]