Study on Working Behaviors and Improvement Strategies of Concrete Cutoff Wall with Slurry Cake in Thick Soil Foundation

Abstract

Concrete cutoff walls are becoming more widely used to control foundation seepage for earth–rock dams built on a thick soil foundation because of the urgent demand for hydroelectric energy. As the lifeline impermeable structure, the safety of the concrete cutoff wall is of great importance and deserves increased attention. However, such walls have often been analyzed through linear-elastic modeling and simulated as a continuous structure. The working behavior of the discontinued concrete cutoff wall with slurry cake is still unclear. This paper presents a three-dimensional (3D) nonlinear finite-element numerical analysis of the concrete cutoff wall in a thick soil earth–rock dam foundation considering the effect of slurry cake. The results indicate that the damage degree and range in the concrete cutoff wall are significantly affected by wall discontinuity and slurry cake thickness. Moreover, the panel joints may open at the downstream side of the wall under the action of lateral water pressure, which will reduce the effective thickness. The joint opening and tensile damage degree decrease with a reduction in panel width, while the compression damage at the lower part of the wall becomes more serious. The thickness of slurry cake should be controlled reasonably because of its obvious effect on damage behavior of the wall. The working behavior of the concrete cutoff wall can be improved by arranging the width distribution of the panel reasonably and dealing with the problem of the slurry cake. This study can provide useful basis and suggestions for the design of a concrete cutoff wall with slurry cake between panels in thick soil foundations.