Assessment of liquefaction potential of unsaturated oil sand tailings subjected to future saturation

油砂尾矿是从油砂中提取沥青过程中的副产品，包括水、沙、细颗粒、残留沥青或其他碳氢化合物。加拿大采矿业生产了大量油砂尾矿，这些尾矿永久储存在大型尾矿库后面。尾矿库的液化流失效和尾矿的无控制释放将对生产、环境、公众认知和生命损失造成灾难性的影响。安全和负责任地管理这些尾矿需要正确了解它们的抗剪强度和抗液化能力。然而，油砂尾矿的液化行为和强度损失，无论是通过地震荷载还是其他触发机制，如降雨、饱和、施工荷载或大坝坡度过陡，都不是很清楚。特别是，部分饱和对现场试验测量和解释尾矿不排水抗剪强度的影响是未知的。这项拟议的研究将利用饱和和不饱和油砂尾矿的强度、硬度、容重和细粒含量来校准广泛使用的现场测试工具-圆锥渗透试验(CPT)。将对油砂样品进行实验室CPT模型试验、剪切波速测量和直接简单剪切试验的综合方案。研究结果将对油砂尾矿的剪切响应和液化行为有新的认识。通过静力触探试验，建立了一种稳健的方法来预测油砂尾砂在动、静载荷作用下的现场强度和液化敏感性。然后，采矿工程师可以在未饱和的油砂尾矿中使用这种方法，以评估尾矿库在饱和时的液化潜力和稳定性。这将使矿山运营商和工程师能够设计更安全的尾矿处置坝，并更好地了解现有大坝面临的风险。这将进一步有利于加拿大，特别是艾伯塔省，通过确保矿藏最终与周围地区整合，并将其改造成环境友好和安全的生态系统，将采矿的环境风险降至最低。

Oil sand tailings are by-products of the bitumen extraction process from oil sands, which include water, sand, fine particles, residual bitumen or other hydrocarbons. Large amounts of oil sand tailings are produced by the Canadian mining industry which are stored permanently behind large tailings dams. Liquefaction flow failure of a mine tailings dam and uncontrolled release of tailings would have a catastrophic impact on production, the environment, public perception, and loss of life. Safe and responsible management of these tailings requires proper understanding of their shear strength and resistance to liquefaction. However, liquefaction behavior and strength loss of oil sand tailings, either through earthquake loading or other triggering mechanisms such as rainfall, saturation, construction loads, or oversteepening of dam slopes are not well understood. In particular, the effect of partial saturation on in-situ test measurements and interpreting undrained shear strength of tailings is unknown. The proposed research will calibrate a widely used in-situ testing tool, the Cone Penetration Test (CPT), with strength, stiffness, unit weight, and fines content of saturated and unsaturated oil sand tailings. A comprehensive program of laboratory CPT model experiments, shear wave velocity measurements, and direct simple shear tests will be carried out on oil sand samples. The results will produce new knowledge in shear response and liquefaction behavior of oil sand tailings. A robust method will be established to predict in-situ strength, and liquefaction susceptibility of oil sand tailings under dynamic and static loads from CPT measurements. Mining engineers can then use this method in unsaturated oil sand tailings to assess the liquefaction potential and stability of tailings dams if they become saturated. This will allow mine operators and engineers to design safer tailings disposal dams and have a better understanding of the risks to existing dams. It will further benefit Canada, and particularly Alberta to minimize environmental risks of mining by ensuring that the mine deposit is ultimately integrated with the surrounding area and reclaimed into an environmentally-friendly and safe ecosystem.