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在城市固废堆场建造运维、污染场地土壤、地下水围封阻隔等环境岩土、污染防治领域中,均会涉及到土体力学行为、孔隙水流动以及污染物运移之间的耦合作用问题。将土体的固结变形分为由力学荷载引起的力学固结变形及由化学荷载引起的化学–渗透固结变形,引入广义达西定律,并考虑土体物理特性和输运性质的动态变化,通过理论推导建立了适用于堆场黏土防渗垫层的水力–力学–化学耦合模型,模型最大的特点是实现了土体固结变形、孔隙流体流动与污染物运移过程之间的全耦合,各模型参数均能够体现耦合效应的影响。采用多场耦合有限元分析软件COMSOL Multiphysics对所建模型进行数值验证和求解,模拟结果表明:所建模型可从机理上描述水力–力学–化学全耦合过程,模拟结果与Peters和Smith模拟结果吻合较好,能够正确揭示超孔隙水压力、污染物浓度时空分布及土体固结变形的演化规律。
In the field of construction and maintenance of urban solid waste storage yards, contaminated soil, groundwater enclosure barriers and other environmental geotechnical, pollution prevention and control, all involve the coupling of soil mechanical behavior, pore water flow, and contaminant transport. problem. The consolidation deformation of soil is divided into mechanical consolidation deformation caused by mechanical loading and chemical-infiltration consolidation deformation induced by chemical loading. The generalized Darcy’s law is introduced, and the dynamic change of soil physical and transport properties is considered. Through the theoretical derivation, a hydraulic-mechanical-chemical coupling model for clay liners in storage yards has been established. The most important feature of the model is that it achieves the full range of soil consolidation deformation, pore fluid flow and contaminant transport processes. Coupling, each model parameter can reflect the coupling effect. Multi-field coupled finite element analysis software COMSOL Multiphysics was used to verify and solve the model. The simulation results show that the model can describe the mechanics of the hydraulic-mechanical-chemical full coupling process. The simulation results are consistent with the Peters and Smith simulation results. Better, it can correctly reveal the temporal and spatial distribution of excess pore water pressure, pollutant concentration and the evolution law of soil consolidation deformation.