Impact of differential settlement of oil sand fine tailings on reclamation covers

油砂细尾矿差异沉降对复垦覆盖层的影响

• 批准号: RGPIN-2019-04573
• 负责人: Beier, Nicholas
• 金额: $ 2.26万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=749024
• 关键词: Impact; differential; settlement; oil; sand

This research program aims to ensure the sustainable development and ultimate reclamation of one of Canada's greatest energy resources, the oil sands. Alberta's oil sand mining region is dominated by several storage ponds containing nearly 1 billion m3 of a clayey mud-like slurry waste called fluid fine tailings (FFT). The oil sands industry has implemented various processes to treat the FFT with some using chemicals and mechanical equipment. The resulting treated tailings (T-FFT) are then placed behind dams creating vast deep tailings ponds. These tailings will then undergo substantial settlement estimated to be 30-50% of the initial height over a period of decades to centuries. Due to the size and inherent variability of the tailings properties within the ponds, this settlement is expected to occur at different rates and magnitudes across the tailings ponds, resulting in what is known as differential settlement (dS) of the tailings surface. The rate and extent of dS has not been thoroughly investigated and quantified for oil sands fine tailings ponds. Significant research and detailed closure and reclamation designs have been undertaken for various soil structures, containment dams or sandy tailings deposits at the oil sands mines. However, none of these deposits will undergo dS to the extent of T-FFT. The reclamation landforms planned for T-FFT deposits include wetlands, ponds, lakes and forests. Should dS continue after the reclamation covers and final landforms are constructed on these T-FFT deposits, there may be detrimental impacts to the surface water balance, groundwater system and overall physical stability. These impacts may ultimately delay or prevent a mine site from achieving its reclamation goal of a "maintenance-free, self-sustaining" landscape. An improved understanding of the impact of dS will lead to more resilient designs of closure landforms. The long-term goals of this research program aim to develop risk management and design approaches to improve reclamation and closure of tailings dams in Canada. The proposed research program will investigate the potential dS arising from various T-FFT deposits, the resulting impact on proposed closure landforms, and quantify the risk to successful closure. Specific objectives of this research program are to: 1) Quantify the dS across T-FFT deposits and its relation to the physical properties of T-FFT. 2) Evaluate the impact of settlement on reclamation covers on tailings undergoing dS. A combination of advanced numerical modeling and laboratory testing in a unique geotechnical testing facility (centrifuge) will be used to estimate the variability in dS in T-FFT and the resulting impact on reclamation covers. The results from the proposed research will be immediately available for oil sand companies and regulators to estimate maintenance and monitoring requirements, evaluate the risk of current tailings pond closure designs, and provide guidance on enhanced design alternatives.

该研究计划旨在确保对加拿大最伟大的能源之一油砂之一的可持续发展和最终开垦。艾伯塔省的油砂挖掘区以几个储藏池为主，其中包含近10亿平方米的粘土泥样泥浆废物，称为流体细尾矿（FFT）。油砂行业已经实施了各种过程，以使用一些化学品和机械设备来处理FFT。然后将所得处理的尾矿（T-FFT）放在大坝后面，形成巨大的深尾矿池。然后，这些尾矿将在数十年到几个世纪以来估计约为初始高度的30-50％。由于池塘内的尾矿特性的大小和固有变异性，预计该沉降将以不同的速度和尾矿池塘的大小发生，从而导致尾矿表面的差分沉降（DS）。尚未对油砂细尾矿池塘进行彻底研究和量化DS的速率和程度。已经针对油砂矿山的各种土壤结构，遏制坝或沙质尾矿沉积物进行了大量研究以及详细的封闭和开垦设计。但是，这些沉积物都不会在T-FFT的范围内进行DS。计划用于T-FFT沉积物的开垦地面包括湿地，池塘，湖泊和森林。如果在这些T-FFT沉积物上构建填海覆盖物和最终地面后，DS继续存在，则可能对地表水平衡，地下水系统和整体物理稳定性产生不利影响。这些影响最终可能会延迟或阻止矿场实现其“无维护，自我维持”景观的开垦目标。对DS影响的改进，将导致更具弹性的封闭地面设计。该研究计划的长期目标旨在开发风险管理和设计方法，以改善加拿大尾矿大坝的开垦和关闭。拟议的研究计划将调查各种T-FFT沉积物引起的潜在DS，对拟议的关闭地面的影响，并量化成功关闭的风险。该研究计划的具体目标是：1）量化T-FFT沉积物之间的DS及其与T-FFT的物理特性的关系。 2）评估定居点对正在进行DS的尾矿的填海覆盖的影响。 在独特的岩土测试设施中（离心机）中先进的数值建模和实验室测试的组合将用于估计T-FFT中DS的变异性以及对填海覆盖的影响。拟议研究的结果将立即用于油砂公司和监管机构，以估算维护和监视要求，评估当前尾矿池塘封闭设计的风险，并提供有关增强设计替代方案的指导。