Research On The Reliability Of The Composite Pilefoundation's Bearing Capacity And Settlement Deformation Control

Composite pile foundation is a kind of special pile foundation structure that comes to bear superstructural load together by natural foundation earth and pile foundation. In recent years, people pay great attention to its theoretical research and application in projects. This paper first summarized and analyzed the various methods for calculating the settlement deformation and bearing capacity of composite pile foundation by analyzing its working properties. According to the "double-control" design principle of composite pile foundation, it analyzed the design method and steps based on "bearing capacity control" and "settlement deformation control" , combining with project examples. Secondly, with analyzing the limit state of the pile foundation's bearing capacity, settlement deformation, and differential deformation, the paper established the corresponding limit state equations, then analyzed and calculated the reliabilities of the composite pile foundation's bearing capacity, settlement deformation, and unequal settlement deformation by using the JC method, studied the influences, come from the statistical value of various variables and parameters, on the reliable index of the composite pile foundation's bearing capacity, settlement deformation, and unequal settlement deformation. The paper also compared the reliability index with the safe coefficient. Based on the analysis of reliability, the paper further researched into the limit state probability design method for the composite pile foundation's bearing capacity, and calculated the partial coefficients of each resistance and load effect, corresponding with the reliability index. Thus the design of the composite pile foundation, based on the reliability, can be applied conveniently to project practice. Finally, based on the "double-control" principle, the paper considered the analysis model of the composite pile foundation system's reliability, which is in series composed of the bearing capacity reliability subsystem and the settlement deformation reliability subsystem, and calculated the reliability index and failure probability of this system. With this ligament, the system's failure probability, we organically combined the control index of the composite pile foundation's bearing capacity with its deformation, and offered a new train of thought and basis for the limitstate design method of composite pile foundation.