深厚覆盖层土石围堰防渗墙结构设计研究

防渗墙良好的工作性态是深厚覆盖层土石围堰正常运行的重要保障,为弄清不同材料、不同设置位置、不同结构型式防渗墙在深厚覆盖层条件下的工作性态,给在该种环境下防渗墙的结构设计提供参考,以某实际工程为研究背景,采用有限单元法,借助ABAQUS大型商用有限元计算软件,对该工程防渗墙的各种方案进行结构计算,得出了不同方案条件下防渗墙的应力、位移变形等规律。根据计算得出的规律从定性与定量2个方面对该工程防渗墙的设计方案进行了优化选择,研究表明采用塑性混凝土防渗墙优于刚性混凝土防渗墙,前者与围堰的变形更协调,更有利于围堰的安全;防渗墙的设置位置对围堰自身的应力、位移变形影响较大,防渗墙设置离上游堰脚1/3堰底宽度的地方优于将防渗墙设置在堰轴线的地方;当一道防渗墙不能满足设计要求,可以考虑采用双防渗墙的结构型式,这种结构型式能大幅度提高围堰的安全裕度。

Design on Structure of Cutoff Wall in Deep Overburden Earth-rock Cofferdam

The good working state of cutoff wall is an important guarantee of the normal operation of earth-rock cofferdam on deep overburden. To understand the working state of cut-off wall on deep overburden in the presence of different materials, different setting positions, and different structural types, and to provide a reference for the structural design of cut-off wall, we conducted finite element calculation for the cut-off wall of an engineering project using ABAQUS software, and obtained the regularities of cutoff wall’s stress, displacement and deformation under different conditions. According to the obtained regularities, we proposed optimized design for the cut-off wall from qualitative and quantitative perspectives. Results reveal that plastic concrete cutoff wall is better than rigid concrete cut-off wall because the deformation of the former is more coordinated with cofferdam, which is conducive to the safety of the cofferdam. The position of cut-off wall has big impact on its own stress, displacement and deformation. Setting the cut-off wall 1/3 of weir bottom width away from the upstream weir feet is better than setting it at the local weir axis. When one single cut-off wall cannot meet the design requirements, we can consider using double cutoff walls, which could greatly increase the cofferdam’s safety margin.