Application Of Cement-soil Mixing Pile And CFG Pile Composite Foundation In Filling

With the prosperity of China's economy and the rapid development of infrastructure projects,multi-pile composite foundation has been more and more widely used by society.But there is still a big difference between the research theory of multi pile composite foundation and the actual project.In this paper,the working mechanism of composite foundation is summarized by consulting a large number of literatures,and the parameters of composite foundation are analyzed by finite element method.The main research and conclusions of this paper are given as follows:(1)By reading a large number of literatures,we can see that the working mechanism of composite foundation is basically similar,which is to adjust the load-bearing ratio between pile and soil through the setting of cushion layer;the composite foundation formed by the combination of different pile types can give full play to the advantages of each pile body to complement each other,coordinate each other,and further increase.The bearing capacity of the composite foundation and the effect of controlling the settlement and deformation of the foundation are increased.(2)The increase of pile length and diameter with larger modulus has more significant effect on reducing foundation settlement than that with smaller modulus.From the economic point of view,the optimum diameter and length can be selected in the design to reduce foundation settlement and save cost.(3)The cushion can obviously alleviate the phenomenon of stress concentration of pile,and the load sharing ratio between pile and soil can be adjusted by changing the thickness of cushion to make the upper load distribution more uniform.The bearing capacity of composite foundation increases with the replacement rate between pile and soil,but when the replacement rate reaches a certain value,its sensitivity to the bearing capacity of composite foundation decreases greatly.The settlement of the composite foundation decreases with the increase of the modulus of the soil between piles,and decreases with the increase of the modulus of the soil layer.(4)According to the rock and soil geological conditions of Honggui Dongsheng project,the integrity and bearing capacity of cement mixing pile-CFG pile composite foundation are tested under low strain and load test.The test results show that cement mixing pile-CFG pile composite foundation can enhance the bearing capacity of foundation.(5)It can be applied to the foundation of new super high rise building in filling site.The pile body of composite foundation is well constructed,the bearing capacity of composite foundation design meets the requirements of design and code,and the structure of pile body is relatively complete,can meet the design requirements.Through the actual project,accumulated experience for the future foundation treatment has a reference and guiding significance.