Nonlinear Stress Analysis of Flexible Pile Composite Foundation by Energy Method

Abstract

To calculate the stress of cement-soil pile (flexible pile) in composite foundation accurately and overcome the defective preposition that the pile and the soil are elastic, the nonlinear analysis and calculation of pile-soil stress by adopting the energy method are performed. First, on the basis of the universally adopted load transfer method, it is assumed that the friction and the relative displacement of the pile shaft conform with the elastic-plastic relationship. Then, the modified Cam-clay model is introduced to calculate the compressive amount of soil around the pile. Further, the stress and strain characteristics curve of the flexible pile is used to calculate the compression of the pile, deducing the energy equation of the pile and soil around the pile, establishing the total potential energy expression of the flexible pile composite foundation, and the load sharing value and the corresponding stress value of the pile-soil are obtained based on the minimum potential energy principle. Finally, this method is verified by indoor laboratory model test and the reported case. The results show that the calculated solutions are in agreement with the measurements; therefore, the calculation method is reasonable.