Abstract: Seepage flow in dam foundation is mainly controlled by the intact degree and the sealing effect of the curtain under dam foundation. Its property is weakened by the long term physical and chemical actions of groundwater. Based on seepage hydraulics and geochemistry theory, multi-fields coupling model for water-rock-seepage curtain of dam foundation was made up of seepage model, solute transport model, geochemistry model and curtain erosion model, and all the models were calculated by FEM. The result proved that the curtain efficiency was weakening all the time. Calcium had been always in dissolution during the time of simulation. The erosion was more quickly in the bottom of the curtain than the top. And it’s the same to the upstream and downstream. Calcium dissolution mainly caused by hydraulic condition and dispersion, and it varied in a non-linear way.

Key words: curtain under dam foundation, solute transport, calcium ion leaching, multi-fields coupling model

摘要： 坝基的渗流动态很大程度上受控于坝基帷幕体的完好程度和止水效果，但由于地下水长期存在的物理-化学作用，造成帷幕体防渗性能的衰减。依据渗流水力学以及水文地球化学的基本理论，建立了反应帷幕体防渗时效的多场耦合作用模型。该模型由渗流模块、溶质迁移模块、地球化学模块及帷幕体侵蚀模块构成，并采用有限元数值法求解。工程实例计算结果表明，帷幕体的防渗效果随着时间的推移越来越差。在整个模拟时段，帷幕体中的可溶类钙质始终处于溶解状态，其不同部位发生溶蚀的强度也不相同，帷幕体底部的溶蚀量要高于其上部的溶蚀量；靠近坝基上游侧的帷幕的溶蚀量要高于下游侧的溶蚀量。钙离子迁移主要由水动力条件和弥散作用共同引起，且坝基各点的钙离子浓度随时间呈非线性变化。

关键词: 坝基帷幕体, 溶质迁移, 钙离子侵析, 多场耦合