路堤荷载下砼芯砂桩复合地基固结沉降特性OA

A comparative in-situ experimental study is conducted to investigate the surface settlement,layered settlement,and pore water pressure dissipation of composite foundations reinforced with concrete-cored sand(CCS)piles and PHC pipe piles under embankment loading.Considering the annular drainage boundary condition of the CCS piles,a formula for the consolidation degree calculation of the composite foundation under staged loading is derived,and the degrees of consolidation of the two composite foundations are compared.The results show that the surface settlement of the CCS pile composite foundation during construction is 4 cm greater than that of the PHC pipe pile composite foundation.The layered settlement of the CCS pile composite foundation is larger,which enables full mobilization of shaft friction along pile shafts and increases the depth of load transfer.In the CCS pile system,the sand pile serves as a drainage channel,which accelerates the dissipation of excess pore water pressure,increases the degree of consolidation during construction,shortens the embankment filling period and foundation settlement stabilization time,and reduces post-construction settlement.Under staged loading,the degree of consolidation of the CCS pile composite foundation is 35%higher than that of the PHC pipe pile composite foundation.The findings of this study can provide important guidance for the design and construction of similar projects.