Method for calculating the bearing capacities of caisson foundations considering the effects of caisson construction

Abstract

Theoretical analysis of the effects of caisson on the bearing capacities of large caisson foundations was performed, with the slip line simplified as a polyline. Based on the limit balance of forces in active zone, transition zone and passive zone, a simplified bearing capacity algorithm for caisson shaft wall or partition wall with no buried depth and no excavation is established. The effects of caisson excavation on the caisson foundation bearing capacity were examined, and a theoretical formula for estimating the caisson shaft wall or partition wall bearing capacity considering the effects of the angle and depth of excavation was derived. At the same time, the influence of soil weight and the extension of soil slip line from the bottom of the foundation to the surface on the bearing capacity of the foundation is analyzed when there is a certain buried depth between the shaft wall and the partition wall, and a formula for calculating the bearing capacities of buried caisson foundations was proposed. According to the calculation method of caisson shaft wall or partition wall proposed in this paper under the condition of no buried depth and no excavation, combined with the world’s largest north anchor caisson project of Wufengshan Yangtze River Bridge, the plate loading test and inversion analysis are carried out. The results of the test and the simplified calculation method of foundation bearing capacity are in good agreement, and the error of the inversion value and the theoretical calculation value are within 5%. For the theoretical calculation method of foundation bearing capacity considering foundation excavation and buried depth, experiments, inversion analysis or numerical simulation will be carried out to verify the accuracy of the calculation method.