Study On Application Of Assembled Foundation With Micro Steel Pipe Pile

The cast-in-place reinforced concrete foundation is mainly used in the transmission line project,which has a large amount of manual work,high cost and great impact on the environment.The micro steel pipe pile foundation has the advantages of high bearing capacity,small settlement and good environment al protection performance.It will greatly improve the construction efficiency of the transmission line project,save resources and have a wide range of social and economic benefits if it is combined with the assembled foundation.(1)Based on a line project in Cangzhou,this paper puts forward a kind of assembled foundation of micro steel pipe pile.Firstly,the bearing capacity of micro steel pipe pile is studied by static load test on site.Then,ABAQUS finite element software is used to study the bearing capacity of micro steel pipe pile assembled foundation under different loads,the connection structure between pile top and pile cap,and the connection between column and pile cap on pile cap The main work and research results are as follows:(2)Through the static load test of single pile in the field,the compression,uplift and horizontal bearing capacity of single pile with different grouting technology are studied.The results show that: under the static pressure pile driving technology,the pressure resistance,pull-out resistance and horizontal bearing capacity of the micro steel pipe pile with the diameter of the welding plate of the pile tip larger than that of the pile body are all higher than that of the micro steel pipe pile with the diameter of the welding plate of the pile tip equal to the diameter of the pile body when the grouting is not carried out.The bearing capacity of the post grouting steel pipe pile can be calculated according to the ordinary cast-in-place pile,and the diameter of the pile tip is taken as the diameter of the pile.(3)According to the field test results and the actual engineering conditions,the design of assembled foundation of micro steel pipe pile is completed.By using ABAQUS finite element software,the bearing capacity of fabricated micro steel tubular pile foundation under different loads is studied.The results show that the load-bearing capacity of the fabricated foundation based on the current code meets the engineering requirements.The change of pile diameter and pile spacing has an effect on the uplift and horizontal bearing capacity of micro steel tubular pile group.Increasing the pile spacing can improve the compressive bearing capacity of pile group foundation.When the pile spacing is more than 6 times of the pile diameter,increasing the pile spacing has no obvious effect on improving the compressive bearing capacity of pile group foundation.(4)According to the engineering experience,the current code and the results of finite element analysis,the structural requirements for the connection design of the assembled foundation of micro steel tubular piles are given.