Refined Three-Dimensional Model of Concrete Cutoff Wall in Deep Overburden for Dynamic Numerical Simulation

The mechanical performance of concrete cutoff walls in deep overburden is decisive for dam safety. Current coarse mesh models struggle to accurately simulate their response under complex conditions. In this paper, a refined numerical model is established specifically for a concrete cutoff wall in deep overburden. The deformation and stress characteristics and mesh sensitivity of the cutoff wall are systematically investigated. A quantitative index of overstress area ratio is introduced innovatively, and the effects of cutoff wall mesh size along the thickness direction, dam height, and overburden parameters on the deformation and stress characteristics of the cutoff wall are explored in detail. The results show that the stress characteristics of the cutoff wall requires a fine mesh model with an element thickness ≤ 1/4 of the cutoff wall. The change in dam height and overburden parameters mainly affects the stress magnitude of the cutoff wall but does not change its tensile stress distribution pattern. The variable-size mesh generation achieves collaborative optimization of accuracy and efficiency, and the calculation amount is significantly reduced by about 16%, with error below 5%. This study presents an efficient method and can provide technical support for the safety evaluation of concrete cutoff walls in deep overburden.