土工膨润土防水毯在不同酸碱度下的防渗性能及其机理研究

Geosynthetic clay liners (GCLs) are increasingly considered for deployment as hydraulic barriers in heap leach pads and waste rock dumps. As a result, there is a high probability that they may come into contact with aggressive leachates having non-neutral pH, a great need to understand their seepage performance and mechanism under these acidic and alkaline conditions. In this study, parameters, such as liquid/plastic index, swell index and fluid loss, of bentonite component in a GCL would be determined with different pH solutions in order to establish the quantitative relationship between GCLs’ hydraulic conductivity and these parameters,by this way, the hydraulic conductivity of a GCL could be estimated. Based on the law of conservation mass and the Darcy’s law, the hydraulic conductivity could be back-calculated with the fluid loss results to provide a quick and effective method to evaluate the hydraulic performance of a GCL. The flexible-wall hydraulic conductivity tests would be conducted so as to determine the hydraulic performance of a GCL under different conditions (different pH, effective stress and pre-hydration). Micro-structure of bentonite component would be observed using X-ray fluorescence, scanning electron microscopy, transmission electron microscopy and infrared spectroscopy to obtain the rules of micro-structure changing under different pH solutions. These micro information would be correlated with the macro hydraulic performance of a GCL. The seepage mechanism of a GCL would be clarified in this study and would provide the reference for future studies regarding GCLs’ applications under pH conditions.

针对土工膨润土防水毯（Geosynthetic Clay Liner,GCL）在尾矿处理、堆浸法选矿等酸碱条件下的应用，其防渗性能及机理欠明确。本项目通过综合分析不同酸碱度下膨润土组分的各项性质指标变化（包括液塑限、自由膨胀指数及滤失量），建立其与GCL渗透系数之间的量化关系，评估GCL的防渗性能；基于质量守恒原理和达西定律，建立不同酸碱度下滤失量推导渗透系数的计算模型，提供快速评估GCL防渗性能的有效手段；采用三轴柔壁渗透试验，揭示多条件下（不同酸碱度、有效压应力、预水化条件等）GCL的防渗性能变化规律，并构建GCL防渗性能综合评价体系。以GCL中膨润土组分为研究对象，采用X荧光光谱分析、扫描电镜、透射电镜、红外光谱分析等方法，进行膨润土微观结构变化研究，建立膨润土微观结构变化与GCL宏观防渗性能间的表征机制，揭示GCL在不同酸碱度下的防渗机理，为后期GCL在不同酸碱度下的应用奠定基础。

针对土工膨润土防水毯（Geosynthetic Clay Liner,GCL）在酸碱条件下的应用时其防渗性能及机理欠明确的问题，本项目通过综合分析不同酸碱度下GCL中膨润土组分的各项性质指标变化，建立了各指标与GCL渗透系数之间的量化关系；采用三轴柔壁渗透试验，揭示了多条件下GCL的防渗性能变化规律，构建GCL了防渗性能综合评价体系。并以膨润土组分为研究对象，采用扫描电镜、透射电镜、红外光谱等测试分析方法，研究其微观结构变化，建立膨润土微观结构变化与GCL宏观防渗性能间的表征机制，揭示GCL在不同酸碱度下的防渗机理，为GCL在不同酸碱度条件下的应用奠定基础，圆满完成了既定目标。