Study on the Combined Bearing Characteristics of Cutoff Wall-Double Row Piles Composite Foundation

The combination system of cutoff wall and double row piles, as a new type of composite reinforcement structure, can take into account the foundation reinforcement needs of the upper structure’s bearing capacity and the water-rich strata seepage interception. Based on a case of the cutoff wall and double-row piles combination reinforcement foundation at a large ship lock project in Lu’an City, Anhui Province, China, the combined bearing characteristics of the composite reinforcement structure are systematically studied in this study through three-dimensional refined modeling of the geological materials and the reinforcement structural systems. The numerical modeling results indicate that the joint-bearing characteristics of the composite foundation are significantly influenced by the elastic modulus of the material in the linking region between the cutoff wall and the upper structure, as well as the size of the upper load. As the elastic modulus of the linking region increases, the stress, displacement, and load-sharing ratio of the cutoff wall increases. The load-sharing ratio contributed by the cutoff wall decreases significantly from 22% to 3.8% when the elastic modulus of the linking region decreases from 20 GPa to 0.2 GPa. The smaller the upper load, the smaller the load-sharing ratio contributed by the cutoff wall. To protect the cutoff wall and better utilize its seepage-proofing performance, a flexible connection is suggested to be used in the linking region between the cutoff wall and the upper structure, and the upper load level should be controlled. The research has reference significance for better studying the bearing characteristics of composite foundations.