Centrifugal Model Tests on the Bearing Capacity of Piles with Basement Construction Under the Existing Building

Abstract

It is a reasonable choice to solve the problem of the limited space and the contradiction of land use in the urban areas by basement construction beneath the existing building. The excavation beneath the existing building will change the stress state of the soil around pile foundation and thus affect the post-excavation pile foundation behavior. A series of centrifuge tests are conducted to study the influence of basement excavation on the bearing capacity of single pile under typical geological conditions in Chengdu, Sichuan. Modelling the existing building by loading on the top of the pile foundation, the relation between different excavation depths and pile foundation characteristics is studied, including ultimate bearing capacity, the axial force and shaft resistance of piles. The test results show that excavation beneath existing building has great influence on the ultimate bearing capacity of both single pile and pile groups. The ultimate bearing capacity of single pile decreased by 11.8% after 4 m excavation of a 20 m long pile, while 35.3% after 8 m excavation. With the increase of excavation depth, the axial force and shaft resistance of pile beneath the excavation face gradually develop. The test results can provide some reference for the design of excavation construction beneath the existing building.