溪洛渡拱坝蓄水期谷幅变形驱动机制研究

Study on mechanism of reservoir valley width deformation during impoundment of Xiluodu arch dam

溪洛渡谷幅变形的产生机制尚存在争议,是当前工程界的难点问题。通过对锦屏一级及溪洛渡谷幅变形典型案例的对比分析,认为溪洛渡谷幅变形具有大量值、大范围和整体性的特点。以变形加固理论的弹塑性方法作为黏塑性方法的近似,引入孔隙弹塑性有效应力,结合溪洛渡库区的水文地质构造背景,计算结构塑性变形的驱动力——不平衡力,研究水库蓄水后控制溪洛渡谷幅变形的关键位置。研究结果表明,水库蓄水后孔隙压力增加引起的不平衡力主要集中在河谷底部的玄武岩层内和层间错动面中,可驱动岩体沿结构面产生大范围变形,这可能是控制溪洛渡谷幅变形的主要机制。

The mechanism of the deformation of Xiluodu Valley is still controversial,which is a key problem in the current engineering field.Based on the comparative analysis of Jinping I and Xiluodu valley deformation,the valley deformation of Xiluodu shows the feature of large value,large scale and integration.In this paper,we adopt the elasto-plastic method of deformation reinforcement theory as the approximation of visco-plastic method,and take the pore elastoplastic effective stress and the hydrogeological structure of Xiluodu Reservoir area into account.The key location which controls the Xiluodu valley deformation is studied by analysing the unbalanced force,which drives the plastic deformation of structure.The results indicate that the unbalanced force caused by the increase of pore pressure after impoundment is mainly concentrated in the basaltic layer and the interlayer dislocation plane at the bottom of the valley,that could drive the rock mass to produce large-scale deformation along the layers and may be the primary mechanism of the structural valley deformation of Xiluodu.