Reserch On Working Properties Of Rigid Long-short-pile Composite Foundation

When the building higher requirements to the construction site or the complicated geologic conditions of foundation bearing capacity,the rigid long short pile composite foundation treatment,can effectively enhance the bearing capacity of the foundation,reduce the settlement,has good economic and social benefits.Based on the background of a high-rise residential rigid long short pile composite foundation engineering,on the basis of field of single pile and multi pile composite foundation static load test,using the method of finite element simulation analysis,research on the working behavior.The main contents and conclusions are as follows:(1)The scene of single pile and multi pile composite foundation static load test results based on the finite element simulation of pile group,the working mechanism of the rigid long short pile in the project were analyzed,obtained the raft foundation and the rigid long short pile composite foundation settlement performance characteristics of large middle and small round.With the increase of load,the axial force of the pile with different pile types increases,and the axial force of the middle pile is larger than the angle pile,and the stress ratio of the long short pile is gradually increasing.(2)Changing the length of the pile and the spacing between the piles will affect the working behavior of the rigid long and short pile composite foundation.Finite element analysis shows that the long pile length increases and pile spacing is conducive to improve the bearing capacity of composite foundation,reduce the settlement;increasing long pile length,the load becomes large;reduce the pile spacing,pile length pile soil stress ratio decreases.(3)When the design of rigid long and short pile composite foundation is reasonable,the pile length and the spacing between the long piles can be reasonably determined,and the ideal load sharing ratio between piles and soil can be achieved.In this paper,when the length of the long pile is 8.5 m and the spacing between piles is 1.2 m,the settlement of composite foundation is smaller,and the bearing capacity of the long and short piles and the soil between them is more adequate.