Analysis of the Load Sharing Behaviour and Cushion Failure Mode for a Disconnected Piled Raft

Disconnected piled raft (DPR) foundations are characterized by having no structural connection to a raft. The raft-pile gap is filled with a granular cushion, which creates a more uniform pressure distribution on the raft and reduces the differential settlement. A series of tests has been performed to investigate the load transfer mechanisms of a DPR. The effects of the thickness and stiffness of the cushion and the pile diameter are presented and discussed. A simple failure mode of the cushion is also put forward according to the cushion slip plane obtained by using the digital image correlation technique that tracks the pixels in the images and generates a displacement field. Then a new theoretical analysis has been presented for rigid pile composite foundation. Through comparative studies, it is found that the present method is validated as reasonable by laboratory tests and is in agreement with several current design methods.

Character Analysis of Balance and Imbalance of Varying Rigidity of Rigid Pile Composite Foundation under Seismic Load

Based on ABAQUS finite element analysis software simulation, the finite element model for dynamic analysis of rigid pile composite foundation and superstructure interaction system is established, which selects the two kinds of models, by simulating the soil dynamic constitutive model, selecting appropriate artificial boundary.The influence of rigid pile composite foundation on balance and imbalance of varying rigidity is analyzed under seismic loads. The result shows that the maximum bending moment and the horizontal displacement of the long pile is much greater than that of the short pile under seismic loads, the long pile of bending moment is larger in the position of stiffness change. By constrast, under the same economic condition, the aseismic performance of of rigid pile composite foundation on balance of varying rigidity is better than that of rigid pile composite foundation on imbalance of varying rigidity.

Analysis of the Settlement in Rigid Pile Composite Foundation

On the basis of rigid pile composite foundation mechanism, This paper makes assumptions and establishes settlement calculation models, then applies shear displacement method to solve interaction flexibility coefficient of the pile-soil system and raises a rigid pile settlement calculation method, considering the effect of cushion.By calculating a certain experiment, it was found that theoretical and measured values of the relative error is smaller ,which can provide a reference for settlement calculation of rigid pile composite foundation in engineering.

Prediction of Composite Foundation Settlement Based on Multi-Variable Gray Model

In this paper, based on the principle of gray theory, MGM(1,n) multi-variable settlement prediction model was established. Combined with specific examples of projects, settlement of rigid pile composite foundation was predicted, and the prediction results are compared with both prediction results of GM(1,1) gray model which is currently comparatively mature and the settlement observation results. The study shows that it is effective to use MGM(1,n) multivariate gray model to predict composite foundation settlement.