Collaborative Research: Experimental and Computational Investigation of Consolidation-Induced Contaminant Transport for High Water Content Geo-Materials

该项目的目标是在我们对高含水量土工材料固结诱导污染物迁移的机制和意义的理解方面，推进最先进的技术。在岩土工程和环境工程的各种实际应用中，会出现固结和污染物运移耦合的现象。这些应用包括在非原位工程水库中对受污染的高含水量土工材料（如尾矿、疏浚、污泥和泥浆）进行密闭处理，对受污染的高含水量土工材料进行机械脱水，通过注入颗粒状零价铁（ZVI）泥浆和土壤混合对受氯化溶剂污染的源区进行原位修复，以及对水下受污染的沉积物进行原位封盖。最近的研究表明，固结诱导的污染物迁移是一种有效的迁移机制，可能对给定系统的污染物迁移行为产生持久的影响。然而，人们对这种机制在实际应用中的一般意义知之甚少。目前对固结引起的污染物迁移的理解在以下方面是有限的：(1)较高的化学浓度和多物种污染物的影响，例如通常发生在现场的污染物；(2)胶体颗粒促进运输的重要性，这可能是具有高吸附污染物的天然细颗粒材料的重要机制；(3)实际土工材料的测试，如矿山尾矿或疏浚沉积物；(4)在恒定应变速率或离心机加载条件下不需要做功。建议的研究将包括对几种材料和条件下固结引起的污染物迁移机制的基础实验和计算调查，然后评估这些发现对相关岩土工程和地质环境应用的意义。研究计划有六个任务：(1)材料采购和表征；(2)材料性能测试；(3)固结诱导输运试验；(4)计算模型的开发和验证；(5)计算模拟；(6)项目协作和成果传播。拟议的研究在对这种运输机制和相关参数的基本评估方面具有内在的科学价值，并且在提高我们预测固结期间高含水量地质材料中污染物流出的能力方面具有实际意义。因此，将更好地了解固结引起的污染物运输的机制和意义，从而提高设计者和监管者保护公众健康和环境免受污染物影响的能力。这项研究的结果有可能改变目前污染的高含水量土工材料的表征、处理、脱水和/或处置方式。

The goal of this project is to advance the state-of-the art with respect to our understanding of the mechanisms and significance of consolidation-induced contaminant transport for high water content geo-materials. The phenomenon of coupled consolidation and contaminant transport occurs for a variety of practical applications in geotechnical and geoenvironmental engineering. Such applications include confined disposal of contaminated high water content geo-materials (e.g., tailings, dredgings, sludges, and slurries) in ex situ engineered impoundments, mechanical dewatering of contaminated high water content geo-materials, in situ remediation of source zones contaminated with chlorinated solvents via injection of granular zero valent iron (ZVI) slurry and soil mixing, and in situ capping of subaqueous contaminated sediments. Research has demonstrated only very recently that consolidation-induced transport of contaminants is a valid transport mechanism that may have lasting effects on the contaminant migration behavior for a given system. However, little is known about the general significance of this mechanism for practical applications. Current understanding of consolidation-induced contaminant transport is limited with respect to: (1) the effects of higher chemical concentrations and multispecies contaminants, such that typically occur in field sites; (2) the importance of facilitated transport via colloidal particles, which is likely to be an important mechanism for natural fine-grained materials with highly sorbed contaminants; (3) testing of realistic geo-materials, such as mine tailings or dredged sediments; and (4) absence of work conducted for constant rate-of-strain or centrifuge loading conditions. The proposed research will consist of a fundamental experimental and computational investigation of the mechanism of consolidation-induced contaminant transport for several materials and conditions, and then assess the significance of these findings for relevant geotechnical and geoenvironmental applications. The research plan has six tasks: (1) material procurement and characterization; (2) material property testing; (3) consolidation-induced transport testing; (4) development and validation of computational models; (5) computational simulations; and (6) project collaboration and dissemination of results. The proposed research has both intrinsic scientific merit in terms of a fundamental assessment of this transport mechanism and associated parameters as well as practical implications in terms of improving our ability to predict contaminant outflows from high water content geo-materials during consolidation. As a result, a better understanding of the mechanism and significance of consolidation-induced contaminant transport will be achieved, thereby enhancing the ability of designers and regulators to protect the public health and the environment from the effects of contaminants. Results from this research have the potential to transform the way contaminated high water content geo-materials are currently characterized, handled, dewatered and/or disposed.