蒸发塘岸坡土工膜防渗层力学响应分析

Mechanical response of geomembrane seepage barrier in side slope of an evaporation pond

含防渗层的蒸发塘不仅可储存废液减免污染,还可通过蒸发结晶提取废液中的盐类,获取经济效益。在缺少黏土等天然防渗层的地区,土工膜等人工合成材料防渗层是控制蒸发塘所蓄废液外渗的关键,其物理力学性能与防渗效果紧密相关。在施工和运行过程中,柔性土工膜会与其赋存的岩土体等相对刚性的环境产生相互作用,从而影响土工膜的力学性能。鉴于此,以一位于寒区的蒸发塘为例,基以过程模拟的方法,研究了蒸发塘土工膜防渗层这一赋存于相对刚性环境中的柔性结构在施工、蓄水和塘水结冰条件下的力学响应。研究表明柔性土工膜与其赋存的相对刚性的地基层和保护层之间存在界面相对摩擦和同向变形协调两种作用,塘内蓄水、结冰等外界环境的作用可通过保护层间接作用于土工膜防渗层。锚固沟处土工膜易应力集中,锚固沟设计和施工时建议遵循"可拉动不拉断"。数值模拟中当土工膜防渗层的最大变形受到模拟方法的限制时,可利用应力判别运行状态。

The evaporation pond with seepage barrier can store waste liquid, limit pollution and extract solution through evaporation by sunlight. In the areas without natural barrier, such as clay, geomembrane is usually applied. So the physical and mechanical properties of geomembrane are essential to the seepage controlling. During construction and operation of evaporation ponds, soft geomembrane will interact with the surrounding relative rigid foundation and protection cover, and its performance is affected. Taken an evaporation pond sited in cold region as an example, the mechanical response of geomembrane to construction, impounding and expansion of ice is investigated. It is shown that two interactions exist between the geomembrane and the surrounding materials. One is interface friction and the other is coordinate deformation along the same direction. The effect of impounding and expansion can be applied to the geomembrane through protection cover. Stress concentration appeares at anchor trench, thus the geomembrane should be able to move in the anchor trench before breaking. If the simulated deformation is limited by the ways of modelling, stresses should be taken to determine the state of geomembrane.