蓄水初期库盘非稳定渗流场时空演化与谷幅变形规律分析

The Temporal and Spatial Evolution of Unsteady Seepage and the Valley Deformation of Reservoir Basin During Initial Impoundment Period

为揭示蓄水初期谷幅变形的产生机制,基于饱和-非饱和非稳定渗流应力耦合分析方法,模拟了初期蓄水过程中库盘非稳定渗流场的时空演化和谷幅变形的发展过程;通过建立岩体遇水劣化模型,研究了饱水过程中库盘岩体力学性能逐渐劣化对谷幅变形的影响;此外,分析了考虑岩体基质压缩性与存在强透水地质缺陷时的谷幅变形规律.结果表明,在蓄水引起的渗流应力耦合作用下,谷幅变形的一般规律为先扩张后收缩,谷幅收缩的直接致因是库盘岩体有效应力的降低;岩体遇水劣化会直接影响谷幅变形的量值,劣化程度越高,谷幅变形量越大;岩体基质可压缩性越强,谷幅收缩量越小;库水位变化高程范围内的强透水地质缺陷会导致谷幅出现收缩变形的时间提前和谷幅收缩变形更快趋于收敛.

To reveal the generation mechanism of valley deformation during initial impoundment,the spatiotemporal evolution of the unsteady seepage field in the reservoir basin and the development of valley deformation during the initial impoundment period are firstly simulated by performing the saturated-unsaturated seepage and stress coupling analysis.Then,the effect of the gradual deterioration of rock mass during the saturation process is investigated by utilizing the proposed rock mass deterioration model.Afterwards,the influences of both rock matrix compressibility and strong permeable geological defects on valley deformation are analyzed.Numerical results show that the valley expands at first and then shrinks due to the coupling effect of seepage and stress,and the fundamental cause of valley shrinkage is the reduction of effective stress of rock mass in the reservoir basin.Both the rock mass deterioration and rock matrix compressibility affect the magnitude of valley deformation.The higher the degree of degradation is,the greater the magnitude of valley deformation is.The stronger the rock matrix compressibility is,the less the valley shrinkage is.Moreover,the geological defects with high permeability leads to the valley shrinks earlier and the shrinkage deformation converges faster.