Contrast research of bearing behavior for composite foundation with tapered piles and cylindrical piles

Based on the shear displacement method, the Mylonakis & Gazetas model for mutual action between pile and soil, and the Winkler foundation model were introduced; then the flexible factors for mutual actions between pile and pile, pile and soil, soil and soil were provided. An analysis method to pile-soil-cushion mutual action in the composite foundation was deduced; and the correlated program was also developed by Matlab software. In order to validate the feasibility proposed approach in this paper, two static load model tests for the composite foundation with tapered piles and cylindrical piles were done in laboratory respectively; and the method was used to analyze two models. Experimental and theoretical results indicated the reaction force distribution of surrounding soil in pile-top plane keeps saddle type, which is similar to natural foundation; the bearing capacity of composite foundation with tapered piles is higher than that of composite foundation with cylindrical piles; and the average pile-soil stress ratio of composite foundation with tapered pile is lower than that of composite foundation with cylindrical piles obviously; tapered pile can relief pile-tip stress concentration in composite foundation effectively; and it has good regulation on using the bearing capacity of natural foundation fully.