Research On Work Mechanics And Settlement Of Gravel Pile Composite Foundation

In recent years, gravel pile composite foundation has been used in many engineering projects which show many great economic and social benefits, but the research on the composite foundation and the knowledge on its behaviors are still inadequate.Now it has been discussing and studying gradually . So combining with the item"soft foundation treatment monitoring and Experimental Research of Daqing-Guangzhou Expressway in Hubei Province from Macheng to Xishui" , it studies deeply the mechanics of bearing capacity and methods for settlement calculation of gravel pile composite foundation through theory analysis,field test numerical simulation and back analysis and so on. The main contents of the research are as follows:At first ,under the base of inheriting former conclusions critically, this paper summed up the mechanism and calculating methods and so on for the gravel pile composite foundation, in which bearing capacity and settlement calculations of composite foundation are the focus of this paper.Gravel pile test section is set in DaGuang expressway and soft clay foundation supported by gravel piles is studied through field tests. At the first phase ,we do the dynamic penetration test for monitoring gravel pile density and static load test for the gravel pile foundation,and analyse the effect of the reinforced composite foundation. At the second phase , during the embankment building process ,we monitor the settlement and deformation of composite foundation.Based on the pore pressure and settlement data and so on, the deformation and distribution of stress in the composite foundation was measuerd.The construction of soft clay foundation reinforced by gravel piles are proposed.Selecting the monitoring data of a typical cross-section, through statistical analysis,regression analysis,we get the effective soil pressure which impacts the changes of displacement, and the physical and mechanical parameters by inverse analysis combined simulated model with FLAC^3D.The three dimensioned calculation model of composite foundation supported by gravel pile is established by FLAC3D, which is according to the DaGuang freeway K84+000 working section.Model simulates the embankment building process. Stress and strain data contrast is done between original subgrade and field test.The numerical simulation results indicates, compared with the original subgrade model, that the model of reinforced composite foundation increases of the bearing capacity of weak subgrade and decreases highly the vertical settlement.Meanwhile, the data of simulation analysis is compared with the filed test.