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: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=710685
• 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.

造成灾难性后果的尾矿坝溃坝继续经常发生。 2015 年巴西和 2014 年不列颠哥伦比亚省（波利山）最近发生的尾矿坝溃坝及相关环境灾难只是最广为人知的两起事件：巴西的尾矿坝溃坝造成了超过 70 亿美元的损失，波利山的尾矿流入克内尔湖，该湖是世界上最大的原始淡水水体之一，也是不列颠哥伦比亚省水道的重要组成部分。 鲑鱼渔业。尽管之前采取了一些改善尾矿坝安全和尾矿蓄库管理的举措，但这些故障仍然继续发生。 大坝溃决的灾难性后果，即尾矿在决口或流出后移动的距离，可归因于至少两个因素：i）尾矿顶部存在的水可能会推动尾矿，以及ii）在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。实践中存在很多关于这两个因素的相对贡献的猜测。最近的研究表明，尾矿在高应力水平和相对高的密度下很容易塌陷。此外，众所周知，尾矿的流变性（控制尾矿在溃坝后流动多远的材料特性）很容易在高剪切速率后退化，正如在大坝溃决期间可能预期的那样。此外，尾矿的结构或尾矿颗粒的排列也会影响崩塌行为。例如，众所周知，干燥会引起织物变化，从而提高强度。 因此，拟议的研究计划调查影响坝倒塌或溃坝后尾矿变形行为的各种因素。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故障，ii）数值模拟，使用大规模物理测试作为校准/验证工具，iii）改变模拟沉积物中的几个因素（气候冻结/解冻或干燥），固结程度，年龄，沉积类型，修正物的使用（废石，胶结尾矿层），以及 iv) 使用多个负载路径进行织物测量和剪切强度测试，以解释大规模测试。拟议的研究将提高对导致尾矿流失的因素的理解，从而改进实践中的方法，以减少或消除此类事件的灾难性后果。