Analysis On Working Behavior And Influence Factors Of Composite Foundation Improved By Concrete-cored DCM Pile

As further acceleration of urbanization process in our country,the scale of engineering construction continues to expand.During the construction of various buildings and structures on the soft foundation,demands for bearing capacity and settlement of foundation are getting higher and higher.Combining high comprehensive strength of concrete pile and large surface area of DCM column,the application of concrete-cored DCM pile can significantly improve the safety and economy of engineering.The existing research on the influence factors of concrete-cored DCM pile composite foundation is not comprehensive enough,as well as the research results of concrete-cored DCM pile composite foundation under flexible foundation.In this paper,firstly axisymmetric analysis model of concrete-cored DCM pile composite foundation under rigid foundation is established by ABAQUS software to analyze the load transfer mechanism and deformation characteristics between precast core pile,DCM column socket and surrounding soil.Effects of six influence factors on working performance of concrete-cored DCM pile composite foundation are also studied,including load level,core ratio,core length ratio,replacement ratio of concrete-cored DCM pile,property of pile-tip soil and cushion thickness.Secondly,based on orthogonal analysis method,influence degrees of the above six influence factors on pile-soil stress ratio and settlement of concrete-cored DCM pile composite foundation under rigid Foundation are compared.Results show that influence of cushion thickness and replacement ratio of concrete-cored DCM pile on the pile-soil stress ratio are more significant,however,the influence of load level and replacement ratio of concrete-cored DCM pile on the settlement of composite foundation are more significant.Finally,difference of the working performance of concrete-cored DCM pile composite foundation between rigid foundation and flexible foundation is compared and discussed.Results show that:(1)There are significant differences of the working performance of concrete-cored DCM pile composite foundation between rigid foundation and flexible foundation.Under the rigid foundation,precast core pile bears the most of upper load.And as load increases,the upper load is transmitted outward from precast core pile to surrounding soil through the DCM column socket.However,under the flexible foundation,surrounding soil bears the most of upper load.As load increases,contrarily the upper load is transmitted inward from surrounding soil to precast core pile through the DCM column socket;(2)When other factors are the same,bearing capacity of composite foundation under rigid foundation will be higher than that under flexible foundation,and the settlement of composite foundation is also less.