Laboratory Study of the Influence of the Excavation of a Foundation Pit on Adjacent Engineering Piles

With the development of urban modernization, the excavation of foundation pits near other existing buildings is increasing, which may influence the normal use of adjacent engineering piles and affect the safety of the superstructure. Taking a project in Lanzhou City, Gansu Province, China, as the background, laboratory experiments for excavation of a foundation pit adjacent to an existing engineering pile are conducted in this study, and the bending moment of the engineering pile, the surface horizontal soil pressure, and the horizontal soil pressure along the engineering pile are monitored. On the basis of verifying the correctness of the laboratory results through the finite-element model, the influence factors, such as engineering pile length, are explored. The results show that the maximum bending moment of the engineering pile caused by the excavation is always located near the bottom of the foundation pit. Increasing the pile length will increase the bending moment of the engineering pile, while increasing the pile diameter and distance between the edge of the foundation pit and the engineering pile could reduce the bending moment. When the end of the engineering pile is above the bottom of the foundation pit, the excavation has little effect on the bending moment of the engineering pile. But when the pile end is located below the bottom of the foundation pit, the bending moment of the pile would be significantly affected by the excavation. Engineering piles outside the foundation pit can serve as supporting piles, greatly reducing the soil pressure acting on the supporting structures. Large-diameter engineering piles can effectively resist the influence of the excavation of adjacent foundation pits. Increasing the distance between the edge of the foundation pit and the engineering pile can also reduce the influence of foundation pit excavation on adjacent engineering piles.