Study On Bearing Mechanism Of Rigid Pile Composite Foundation With Cap

Composite foundation technology is the most effective engineering measures to reinforce soft ground. To withstand greater load or the thick soft foundation, rigid pile or pile net composite foundation technology is usually used to deal with in engineering and vertical generally adopt rigid pile with cap, so as to effectively control of the settlement of composite foundation and stress ratio,improve bearing capacity and stability of the composite foundation. Although the rigid pile with cap is widely used in the engineering practice at home and abroad, However, due to the load bearing mechanism of rigid pile with cap is still at the primary stage, the load transfer mechanism of cap pile(load displacement relationship) is not clear. In composite foundation with cap pile are generally not a single, so the bearing capacity of will be adjacent to the other with pile cap effect, however, how to consider the adjacency effect of capped pile bearing capacity, rarely at home and abroad research,In this paper, the pile cap pile composite foundation is studied from three aspects: the bearing mechanism of the pile cap, the bearing mechanism of the cap pile, the bearing capacity of the pile with the adjacent influence.(1)Summary and analysis of model test and numerical simulation results showed that the similar with the load increasing with rigid cap pile cap foundation soil occurred in the end the whole lateral shear slip failure, the failure modes and shallow foundation. Accordingly, based on the analysis of seismic slope displacement method and displacement of slope stability analysis method based on the idea of, establish a used both for separate analysis of the load displacement relationship of capped pile caps, also can be used to analyze the load displacement relationship of shallow foundation of practical analysis method of sliding displacement method. Finally, the load displacement relation of circular shallow foundation is calculated and analyzed, and the results are compared with the finite element analysis software ABAQUS, the correctness of the sliding block displacement method is verified.(2)Based on the load displacement relation of the upper part of the pile with cap pile, the load transfer method is related to the displacement method of the sliding block and the load displacement relation of the lower part of the pile. The load-displacement relation(P-s curve) for the rigid short pile with enlarged cap was acquired based on the displacement compatibility of the upper and lower parts by using iteration approach. The verification of this technique was performed by comparing with the results of model tests and demonstrated a good agreement between the derived P-s curve and testing data. On P-S curves of the view of the whole process, obtained by the method of theoretical curve and the model test curves are in good agreement, relative error of the average of 8.1%. The method in this paper can calculate big pile cap rigid short pile bearing capacity limit value and the characteristic value is obtained(according to industry standards to limit value of half), its precision can meet the engineering requirements and test results of relative error was 5.9%). And the calculated value of the method is slightly less than the experimental value, and the method is conservative. Therefore, the method is feasible.(3)Through drawing lessons from foreign scholars on the adjacent set of strip foundation bearing capacity calculation model established presence of adjacent pile with cap under the influence of pile with cap failure mode, and according to the failure mode, considering soil weight, cohesion, overloading effect on the bearing capacity, based on the limit equilibrium method had pushed the pile with cap in the presence of adjacent under the influence of the formula for calculating the bearing capacity.