在围岩裂缝与缓冲材料交界处地下水对膨润土的侵蚀作用研究

In the background of the construction of geological disposal repository for high-level radioactive waste in China, a series of tests will be carried out in this project on which are: (1) the anti-erosion capability of bentonite colloids to underground water flow, (2) the hydraulic characteristics of fractured surrounding rock, and (3) the interaction among bentonite, surrounding rock and underground water at the interface between buffer material and fractured rock. The aims of the study are to investigate the process and mechanism of the filling and sealing effect into the rock fractures by bentonite; analyze the initial condition of the erosion effect of flowing underground water on bentonite colloids; and explore the influnce of water properties (flow rate, positive ion type, pH value and chemical composition) and fractured rock characteristics (porosity, hydraulic conductivity, width and distribution of fractures) on the erosion effect of underground water on bentonite. Combined with mechanism analysis for the influence of compacted bentonite erosion on the physical barrier layer's stability, a theoretical model would be established in order to predict the loss of bentonite filling and sealing rock fractures in the long term. The performance of this study would be good reference to the design, construction and safe use of disposal repository, and be important to prevent from or reduce the bentonite erosion problem probably induced by underground water flow in fractured surrounding rock for chinese repository in future.

以我国拟建高放废物地质处置库为背景，通过开展膨润土胶体抗冲蚀试验，地下水对因吸水膨胀而进入围岩裂缝的膨润土的侵蚀试验，带裂缝围岩的水理特征测试，及地下水侵入条件下围岩和膨润土交界处的相互作用试验；探究高压实膨润土填充/密封围岩裂缝的过程及其机理，分析地下水流动对膨润土胶体水力侵蚀的发生条件及过程，揭示地下水特性（流速、离子类型、化学成分、pH 值等）、围岩和裂缝特性（围岩孔隙率、渗透性；裂缝宽度及分布情况等）对地下水侵蚀膨润土作用的影响；结合膨润土颗粒侵蚀对压实膨润土阻隔层物理稳定性的影响机理分析，建立预报围岩裂缝与缓冲材料交界处膨润土流失的理论模型，形成预测和评价膨润土填充/密封围岩裂缝稳定性的方法。本项研究的实施，可望对处置库中膨润土侵蚀问题的防治具有重要的应用前景和实际意义，并为今后我国高放废物地质处置库的设计、施工及长期安全性评价提供参考。

以我国拟建高放废物地质处置库为背景，开展了膨润土胶体抗冲蚀试验，地下水对因吸水膨胀而进入围岩裂缝的膨润土的侵蚀试验，带裂缝围岩的水理特征测试，及地下水侵入条件下围岩和膨润土交界处的相互作用试验；探究了高压实膨润土填充/密封围岩裂缝的过程及其机理，分析了地下水流动对膨润土胶体水力侵蚀的发生条件及过程，揭示了地下水特性（流速、离子类型、化学成分、pH 值等）、围岩和裂缝特性（围岩孔隙率、渗透性；裂缝宽度及分布情况等）对地下水侵蚀膨润土作用的影响；结合膨润土颗粒侵蚀对压实膨润土阻隔层物理稳定性的影响机理分析，建立了预报围岩裂缝与缓冲材料交界处膨润土流失的理论模型，形成了预测和评价膨润土填充/密封围岩裂缝稳定性的方法。本项研究的实施，可望对处置库中膨润土侵蚀问题的防治具有重要的应用前景和实际意义，并为今后我国高放废物地质处置库的设计、施工及长期安全性评价提供参考。