Flowslide of tailings dam: understanding the mechanics of intermediate soils for biomediated tailings improvement

自然资源开采对加拿大经济至关重要;加拿大拥有世界上第二多的尾矿坝。然而，采矿活动继续对业务和公共安全及环境构成风险。由于尾矿坝的破坏，已经释放了惊人的约2.75亿立方米的尾矿，导致超过3 000人死亡。然而，资源开采需求的增加将导致估计每年需要储存100亿立方米的额外尾矿。目前的尾矿坝现场监测程序不足以提供流动液化发展的关键预测（即，固体材料在单调载荷下表现得像流体）;变形过程和触发机制尚不清楚。这些知识差距将导致更多的大坝故障。从根本上更好地了解尾矿行为对加拿大的采矿部门、经济和环境至关重要。拟议的研究整合了尾矿（作为一种中间土壤）的力学，尾矿坝的变形和生物调解方法，以提高对尾矿中流动滑坡的理解和缓解。预计3名博士生将接受最先进的实验室和数值技术的培训，以实现以下研究目标：目标1 i）使用数据优化框架进行荟萃分析，以评估细粒含量对尾矿和其他中间土壤的影响。它是量化粒度组成的影响，以确定适用的参数范围，采用预测尾矿的行为。目的1 ii）是设计和使用运动传感器来研究流动液化开始时土壤结构的倒塌;如果实际发生结构倒塌，垂直加速度的幅度可以揭示颗粒碰撞。目的二是利用离心模型模拟尾矿坝的变形过程。边坡几何形状的变化的影响下，一个传播的潜水面进行了分析，这有望揭示前故障的尾矿坝的几何形状的变化和由此产生的流动收缩，这可能会导致排水条件的转变，触发流动液化。目的3是研究微生物诱导方解石沉淀处理对尾矿力学行为的影响，重点是根据实验室试验和数值模拟的微观结构和渗透率各向异性的变化。研究结果将提供对生物介导土壤的基本认识，这些土壤是充分评估其对尾矿复垦的适用性所急需的。拟议的研究计划将开发首个同类数据库，这将提高我们对尾矿材料流动液化发展以及中间土壤力学的理解，从而改善目前的尾矿管理实践。

Natural resource extraction is essential to the Canadian economy; Canada has the second largest number of tailings dams worldwide. However, mining activities continue to pose risks to operational and public safety and the environment. A staggering ~275 million m3 of tailings have been released due to tailings dam failures, resulting in >3,000 fatalities. Yet the increased demands for resource extraction will lead to an estimated 10 billion m3/year of additional tailings requiring storage. Current field monitoring programs for tailings dams are insufficient for providing critical forecasts for the development of flow liquefaction (i.e., solid materials behave like fluid under monotonic load) of tailings; the deformation process and the triggering mechanism are not well understood. These knowledge gaps will lead to more dam failures. A greater fundamental understanding of tailings behaviour is vital for Canada's mining sector, economy and environment. The proposed research integrates the mechanics of tailings (as a type of intermediate soil), the deformation of tailings dams, and bio-mediation methods to improve the understanding and mitigation of flowslides in tailings. It is anticipated that 3 PhD students will be trained in state-of-the-art lab and numerical techniques to attain the following research objectives: Objective 1 i) use a data optimization framework for a meta-analysis to assess the effects of fines content on tailings and other intermediate soils. It is to quantify the effects of grain size composition to identify applicable ranges of parameters to be adopted to predict tailings behaviours. Objective 1 ii) is to design and use motion sensors to investigate soil structure collapse during the onset of flow liquefaction; the amplitude of vertical acceleration can reveal particle collision if actual structure collapse occurs. Objective 2 is to simulate the deformation processes of tailings dams using centrifuge modelling. Changes of slope geometry under the influence of a propagating phreatic surface are analyzed, which are expected to reveal the pre-failure geometry change of the tailings dam and the resultant flow constriction, which can induce a drainage condition transition that triggers flow liquefaction. Objective 3 is to study the effects of microbial-induced calcite precipitation treatment on the mechanical behaviours of tailings, focusing on the changes in the microstructure and permeability anisotropy in light of laboratory tests and numerical modelling. The results will provide the fundamental understanding of the bio-mediated soils that are critically needed to fully evaluate its applicability to tailings reclamation. The proposed research program will develop the first-of-its-kind data repository, which will improve our understanding of the development of flow liquefaction in tailings materials as well as the mechanics of intermediate soils, and thus improve the current practices of tailings management.