三峡库区寨坝变形体的渗流变形有限元耦合分析

The coupled FEM analysis of deforming slope of Zhaiba,the Three Gorges

三峡库区寨坝民德小学变形体是山前坡积物、崩积物以及滑坡堆积物等的混杂体,中部存在孤立的块碎石含水层,地下水位较高。公路开挖引起了远场集中通道排水疏干和开挖面附近卸载,导致了不均匀变形破坏产生。本文给出了这种开挖卸载与排水疏干共同作用下,边坡饱和-非饱和渗流与变形耦合的有限元分析方法。研究表明,集中通道排水造成了坡体大范围的孔隙水压力下降,从而导致不均匀变形和地面开裂;其中通道排水诱发的不均匀变形将随着排水通道的封堵和地下水位的回升而停止,而纯粹的开挖卸载主要影响开挖面附近的土体变形。这一典型实例所揭示的机理模式,可以解释工程施工区通常出现的因开挖和开挖引起的排水所诱发的远近变形破坏现象的实质。

The deforming slope in Minde primary school, Zhaiba, Yunyang county,the Three Gorges, is consisted of cliff debris, colluvial and diluvial deposits. There is an isolated aquifer, which is consisted of block and rubble stones under the center of the land site, and the underground water level is just below the ground surface. Uneven deformation had been induced by groundwater discharge via some concentrative piping channels due to road excavation in 1998-2000 construction periods. A coupling finite element method (FEM) of saturatedunsaturated soil seepage and deformation calculation has been presented to model the deformation and the ground failure. It has shown that a large range of both descending of pore water pressures and uneven deformation were in fact caused by groundwater discharge. The excavation unloading may only cause deformation of soils near the excavation face.