Calculation of Settlement of Composite Foundation with Rigid Piles under Flexible Ground

According to the character of the interaction of the pile, soil and cushion in composite foundation by fitting the vertical relative displacement distribution function of pile-soil element and introducing an elastic-plastic load transfer model, and deformation form of the pile-soil relative displacement, friction variation of pile, and pile-side soil reaction force model were simplified to a certain degree, and a basic differential equation of settlement calculation of the rigid pile composite foundation was established with consideration of both upward and downward penetration displacements of piles and the coordination of deformation of neutral point and the pile-soil interface. Then, a new method of calculating the settlement of the rigid pile composite foundation considering the interaction of pile-soil-cushion system was developed. At last, this new method was applied to the analysis of a model experiment and a project example, and the results show that (1) there exist great difference between the deformation mode and pile-soil stress ratio of rigid pile composite foundation under flexible ground and those under rigid ground; (2) the calculated results are close to the measured values. This method can reduce the calculation and provide a reference for the settlement calculation of rigid pile composite foundation.