The Characters Of The Consolidation Of Composite Foundation

Composite foundation is an artificial soil composed of basal body (natural foundation) and reinforcement body (piles), its characteristic is that the superimposed loading is shared by the basal body and the reinforcement body jointly and directly. Being applied widely in all the civil engineering, composite foundation is having been yielded good economic performance. Not only the bearing capacity and deformation of composite foundation have greatly interested the academia and the engineers, but also its characteristic of consolidation is having been researched widely and deeply. Relying on the known research findings, a systemic research on the characters of the consolidation of composite foundation has been carried out in this paper:i. The whole in radial direction of the pile and its surrounding soil of composite foundation is regarded as an analytic element respectively, so the effect of smear resulting from the installation of the piles is not necessary to be considered. Based on the equivalent of seepage discharge of an element to its volume change and the concept of the average excess pore water pressure, the analytic equation of consolidation for the composite foundation formed by homogeneous ground was derived. Considering the effect of stress concentration, the calculation formulas of both excess pore water pressure and consolidation percent of the pile and its surrounding soil have been achieved. The parameters of the pile such as permeability, compressibility and replacement ratio, etc., which have effects on consolidation, have been explored in detail respectively and their regularities are generalized;ii. The analytic equations of both excess pore water pressure and consolidation percent of the composite foundation composed of multi-layered ground have been obtained, the parameters of the soil which have effect on consolidation have been researched in order to find out the characters of the consolidation of composite foundation;iii. The consolidation equation of the composite foundation with weaksubstratum has been built up. Through improving the continuity condition between the reinforced zone and the contact face of substratum, the corresponding solutions of the excess pore water pressure and rate of consolidation have been achieved. According to the settlement characteristic of composite foundation, the degree of consolidation of the whole composite foundation has been acquired, which could reflect the consolidation settlement;iv. The feasibility of ABAQUS is tested with one-dimension consolidation theory of Terzaghi, and the friction effect of the pile and its surrounding soil on the consolidation characters of composite foundation is also explored;v. Using finite element method, the change of parameters such as foundation layout, the permeability and compressibility of the pile and its surrounding soil, pile's replacement ratio and foundation stiffness, etc., has been discussed to discover their effects on the consolidation characters of composite foundation. The magnitude and distribution of excess pore water pressure, consolidation settlement and consolidation percent have been calculated and their results are analyzed and generalized.In the paper, the characters of the consolidation of composite foundation are researched amply, a simplified analysis method is brought forward and the continuity condition of composite foundation is improved, which will further rich and perfect the consolidation theory of composite foundation and is of beneficial reference to actual engineering.