Characterization of Static Liquefaction in Tailings through the Critical State Framework

尾矿储存设施（TSF）是用于储存采矿废物的人造土制结构，由提取过程中留下的细矿物和水组成。它们存在于经济、安全和可持续性的交叉点。采矿业需要更好的工程实践来评估和改进现有的tsf，设计新的tsf和处置过程，其动机是：最近tsf的灾难性失败；经济挑战要求降低尾矿处理成本；以及不断变化的监管和社会压力，以提高尾矿储存的安全性和可持续性。颗粒状土壤，如尾矿，会在一个称为液化的过程中失去全部或部分强度。液化是一种现象，当松散的颗粒“想要”形成更致密的结构时，就会发生这种现象，但在空隙中存在的水阻止了这种现象的发生，其代价是水中的压力增加。结果很明显：如果水压足够大，整个混合物就会变成“液体”。土壤的抗液化能力主要取决于其颗粒的密集程度。液化潜力是通过估算土壤密度来评估其对穿透探针的阻力。锥体穿透测试（CPT）是主要的现场表征工具，因为它提供了丰富的信息，快速和廉价的应用。

Tailings storage facilities (TSF) are man-made earth structures used for storing mining waste, comprised of fine minerals and water left behind during the extraction process. They exist at the intersection of economics, safety, and sustainability. The mining industry needs better engineering practices for assessing and improving existing TSFs, designing new TSFs, and disposal processes motivated by: recent catastrophic failures of TSFs; economic challenges demanding reductions in tailings disposal costs; and evolving regulatory and social pressures to improve the safety and sustainability of tailings storage. Granular soils, such as tailings, can lose all or part of their strength in a process called liquefaction. Liquefaction is the phenomenon that happens when loosely compacted particles "want" to form a denser structure, but presense of water in the voids prevents that, at the cost of increasing pressure in the water. The result is obvious: if the water pressure sufficiently increases, the whole mixture will turn into a "liquid". Soils' resistance to liquefaction mainly depends on how densely-packed its particles are. Liquefaction potential is assessed by estimating soil density from its resistance to a penetrating probe. The Cone Penetration Test (CPT) is the predominant site characterisation tool since it provides a wealth of information with fast and inexpensive application. Assessing the potential threat of liquefaction to a TSF involves three steps: How the CPT estimates the density of tailings, if liquefaction will occur given the density of tailings, and how much strength the tailings will retain should liquefaction occur. A consultant (Golder) and a specialty contractor (ConeTec) who often collaborate on TSF projects in Canada and around the world have come together with University of Toronto to pool their expertise and answer these pressing questions. The proposed partnership will produce a new tailings-specific liquefaction assessment framework. Consequently, Canadian consultants, contractors, and mining companies will obtain a competitive edge leading to added work and employment, reduced cost of operation, and most importantly safer designs.