水布垭水库水压应力场、孔压场及形变场分析

本文以Biot的固结理论为基础,利用有限单元法,对水布垭水库未来蓄水后地壳岩石中由于附加水荷载所产生的各种力学效应进行了数值计算。计算中沿清江从招徕河到恩施之间共取剖面48个。认为:(1)水体荷载产生的附加应力场、孔压场和形变场在库岸附近造成压应力差和位移差,特别是分布有附加的张应力,促使库水向外渗透和扩散,导致孔压改变、有效应力降低或增大;(2)水布垭库坝区的张性断裂和喀斯特较发育的地段,由于水体荷载效应和库水的渗透及扩散作用,易沟通地下水的动力联系,使岩体失稳并在浅层易产生倾斜型或倾斜型兼走滑型滑动;(3)孔压和位移一般在库基下几公里深度区域内多形成一个高值孔压和低值位移的变换带,是应力易于集中的场所;(4)水荷载产生的各种附加效应,受蓄水方式和蓄水时间的影响。

ANALYSIS OF THE STRESS, PORE PRESSURE AND DEFORMATION FIELD UNDER WATER LOADS FOR SHUIBUYA RESERVOIR

Based on the Boit's consolidation theory, the numerical calculations of various mechanical effects in rock of earth's, crust under supplementary water loads after water storage of Shuibuya reservoir is carried on with finite element method. Some conclusions are given: 1) The compressive stress difference and deformation difference, especially the distribution of supplementary tensile stress around reservoir bank, which are caused by supplementary stress, pore pressure and deformation field under water loads, make water of resrvoir infiltrate and spread out, resulting in change of pore pressure and decremerit or increment of effctive stress. 2) In the area of tension fractures and developing Karst, the dynamic contact of ground water can be easily linked by the water load effect and the infiltration and spread action of reservoir, so that the dip--slip and dips-- trike-- slip at shallow layer are produced. 3) The high pore pressure and alternate belt of lower displacement are generally formed at the zone of several Kilometers under the reservoir bed rock where stress is easilyconcentrated. 4) Each supplementary effect produced by water loads is influenced by the way and the time of water storing.