Effect of cushion and cover on moisture distribution in clay embankments in southern China

垫层和包边土对中国南方地区黏土路堤湿度分布的影响研究

To achieve durability of the embankment in southern China,a method to control the change of moisture content with the cushion and cover was proposed.A finite element model of cushion and cover considering different materials and thicknesses for a typical embankment was built,and 20 numerical analyses of transient seepage in the embankment were simulated.The results show that the sand cushion effectively blocks the effect of groundwater capillary rise and the minimum thickness of the sand cushion is 75 cm without considering the atmospheric environment.With the combination of sand cushion and clay cover,as the thickness of the clay cover increases,the duration time of the moisture content from the initial to relative equilibrium state increases,but the equilibrium moisture content is the same as that of the original embankment.Besides,with the combination of the sand cushion and sand cover,the moisture content inside the embankment remains the same,which is consistent with the optimum moisture content during construction.The combination of 75 cm sand cushion and 30 cm sand cover is a very effective method to block groundwater and atmospheric environment,and achieve the control of the humidity stability of the embankment in southern China.

为了实现中国南方地区路堤的耐久性,提出了一种运用垫层和包边控制路堤含水率变化的方法。选取典型路堤结构建立了一种考虑不同材料、不同厚度的垫层和包边的有限元计算模型,并开展了20种瞬态渗流模拟。结果表明,在不考虑大气环境影响的前提下,砂垫层有效地阻断了地下水毛细上升的影响,其最小厚度为75 cm。考虑大气环境后,采用砂垫层和黏土包边的组合,随着包边厚度的增加,含水率从初始状态到相对平衡状态的时间延长,但平衡含水率与原路堤的相同。另外,结合砂垫层和砂包边,路堤内部的含水率基本不变,与最佳含水率一致。通过比较分析,75 cm砂垫层和30cm砂包边的组合,可以有效地阻止地下水和大气环境影响,是一种控制南方黏土路堤湿度稳定性的有效方法。