Fabric, rheology, and shear strength for risk reduction in tailings impoundment management

织物、流变学和剪切强度可降低尾矿蓄积管理的风险

• 批准号: RGPIN-2017-06384
• 负责人: simms, paul
• 金额: $ 2.04万
• 依托单位: Carleton University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=665234
• 关键词: Fabric; rheology; shear; strength; risk

The failure of tailings dams with catastrophic results continues to occur with regularity. The recent tailings dam failures and associated environmental disasters in Brazil in 2015 and in British Columbia (Mount Polley) in 2014 are only two of the most well-publisced occurrences: the failure in Brazil resulted in excess of $7 billion dollars in damages, with the tailings from Mount Polley flowed into Quesnel lake, one the largest pristine freshwater bodies in the world, and an important component of the water way for British Colombia's salmon fishery. These failures continue to occur despite several previous initiatives to improve tailings dam safety and tailings impoundment management.******The catastrophic consequences of dam failure, namely the distance the tailings travel after the breach, or runout, can be attributed to at least two factors: i) the presence of water on top of the tailings may push the tailings, and ii) the susceptibility of the tailings themselves to strength loss and high flowability upon the sudden change in stress state following dam breach. Much speculation exists in practice concerning the relative contribution of these two factors. Recent research has shown that tailings are susceptible to collapse up to high stress levels and relatively high densities. Also, it is known that the rheology of the tailings, the material properties that control how far the tailings flow after failure, are susceptible to degradation following high rates of shear, as might be expected during dam failures. Further, the fabric of the tailings, or the arrangement of tailings particles, influences collapse behaviour. For instance, it is known that desiccation induces a fabric change that leads to higher strength.******Therefore, the proposed research program investigates the various factors that influence the deformation behaviour of tailings post-dam collapse or dam breach. This will involve: i) use of an existing large earth testing facility to physical simulate dam failures, and ii) numerical modelling, using the large-scale physical tests as a calibration / verification tool, iii) varying several factors in the simulated deposits (climate – freeze/ thaw or desiccation), degree of consolidation, age, type of deposition, use of amendments (waste rock, layers of cemented tailings), and iv) to conduct measurements of fabric and shear strength test with multiple load paths to interpret large-scale tests . The proposed research will lead to improved understanding of the factors contributing to tailings runouts and therefore to improved methods in practice to reduce or eliminate the catastrophic consequences of such events.

尾矿坝的破坏造成灾难性后果的情况继续经常发生。2015年巴西和不列颠哥伦比亚省最近发生的尾矿坝事故及相关环境灾害（波利山）在2014年只有两个最好的事件：巴西的失败造成了超过70亿美元的损失，波利山的尾矿流入了奎斯奈尔湖，这是世界上最大的原始淡水湖之一，也是英属哥伦比亚鲑鱼渔业水道的重要组成部分。尽管先前采取了一些措施来改善尾矿坝安全和尾矿蓄水管理，但这些故障仍在继续发生。溃坝的灾难性后果，即溃坝或溢流后尾矿行进的距离，可归因于至少两个因素：i）尾矿顶部存在水可推动尾矿，以及ii）溃坝后应力状态突然变化时尾矿本身对强度损失和高流动性的敏感性。在实践中，人们对这两个因素的相对作用有很多猜测。最近的研究表明，尾矿在高应力水平和相对高的密度下容易坍塌。此外，已知的是，尾矿的流变性，即控制尾矿在破坏后流动多远的材料性质，在高剪切速率之后容易降解，如在大坝破坏期间可能预期的那样。此外，尾矿的结构或尾矿颗粒的排列影响坍塌行为。例如，众所周知，干燥会引起织物的变化，从而导致更高的强度。因此，建议的研究计划调查的各种因素，影响尾矿坝后倒塌或溃坝的变形行为。这将涉及：i）使用现有的大型地球测试设施来物理模拟大坝破坏，以及ii）使用大规模物理测试作为校准/验证工具的数值建模，iii）改变模拟沉积物中的几个因素（气候-冻/融或干燥）、固结度、年龄、沉积类型、改良剂的使用（废石、胶结尾矿层），以及iv）进行组构测量和具有多个载荷路径的剪切强度测试，以解释大规模测试。拟议的研究将导致更好地了解造成尾矿流失的因素，从而改进实际方法，减少或消除这种事件的灾难性后果。