Effect of ground improvement on the lateral resistance of closed-end steel pipe piles in a coal ash pond

Abstract

This study assessed the effect of configuration of the ground-improved body to improve the lateral resistance of piles driven into a coal ash pond. Nine closed-end steel pipe piles were studied by lateral load tests in the investigation, which included four test piles and five reaction piles. While TP1 pile was carried out without the reinforcement, TP2, TP3, and TP4 piles were tested with various reinforcements, including grid-type, block-type, and cross-type. The lateral load test results showed that the ultimate lateral loading capacity, pile-head stiffness, and soil resistance of the reinforced piles compared with TP1 pile were increased by 26%–39%, 54%–238%, and 33%–128%, respectively. Conversely, the maximum bending moments of the reinforced piles were reduced by 48%–73%, respectively. Soil-mixing wall reinforcement was found to increase effectively the lateral resistance of the closed-end steel pipe piles in a coal ash pond. However, because a variety of ground-improved body configurations can increase the lateral resistance of piles, the choice of the type of reinforcement must be considered for reliable design, construction feasibility, and economic benefits of engineering practice.