蓄水引起的地基垂直形变的总效应和丹江水库地震

THE TOTAL EFFECT OF THE LOAD OF WATER UPON LOCAL CRUSTAL DEFORMATION AND EARTHQU- AKES OF THE DANJIANG RESERVOIR AREA

  • 摘要: 水库蓄水后,水体质量荷载引起地基岩石介质产生静力学形变效应.发生地震的水库,由于震源区岩石介质扩容,也会引起地基岩石介质的形变.本文同时考虑了这两种效应.水体质量荷载的静力学形变总效应包括:荷载引起的地基岩石介质的静态弹性形变,质量引起的重力等位面形变以及静态弹性形变所引起的重力等位面形变.岩石介质扩容效应在一定阶段会引起地基岩石介质的膨胀隆起,这种隆起形变同样也引起重力场变化.采用上述模型分析了丹江水库的水准测量成果,确定了该地区地基岩石介质的 Lame 常数,分析了地面垂直形变与地震的关系,从而认为使用该模型分析蓄水后库区的地面的垂直形变,可以为预报水库区地震提取必要的信息.

     

    Abstract: After a reservoir was filled with water, the effect on statical deformation in the rock medium of it's foundation is caused by the load of water mass. Morever, the deformation also results from the dilatancy in the rock medium at the foci when some earthquakes occur. In this paper, these two types of deformations have been considered.The total effect of the load of the water mass on statical deformation consists of the statical elastic deformation in rock medium resulting from the water load, the deformation of the gravitational equipotential surface caused by the water mass, and that resulting from elastic deformation. In addition, the upheaval of ground surface due to dilatancy in the rock medium occurs also at certain stages. It induces, at the same time, the variation of the Earth's gravitational field.The results obtained from first order precise levelling prior to and after the filling of the Danjiang reservoir have been analysed based on the model mentioned above. Lame elastic constant of rock medium has been determined and the relation between vertical deformation of ground surface and the earthquakes occurred in this area has been discussed. It is supposed that with this model, studies on the characteristics of the vertical deformation of ground surface after the filling of the reservoir, then, may be possible to acquire certain information for earthquake predication in the area.

     

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