Study On Performance Of CFG Pile And Cement Soil Pile Composite Foundation

With the rapid development of the construction industry,promoting the continuous updating of building technology,some of the original building technology can not meet the needs of social development.Especially in recent years some buildings due to the occurrence of large uneven settlement seriously affect the use of buildings the traditional single pile composite foundation pile layout has brought many problems in some areas.Aiming at this kind of problem,a rigid and flexible pile arrangement method based on the idea of variable stiffness leveling is proposed to improve this kind of problem.At present,variable stiffness leveling methods mainly include variable pile length,variable pile diameter and pile spacing,etc.,which are widely used in engineering.Based on the finite element software ABAQUS and combined with engineering examples,this paper established the rigid-flexible pile model,analyzed the influence of flexible piles arranged in different positions on the settlement of composite foundation,discussed the variation law of settlement,and put forward an optimization plan to reduce the uneven settlement of the project.The main contents are as follows:1.Based on the CFG single pile test report,the finite element single pile model was established,and the load settlement curve of the test pile report was fitted by using the same loading method as the single pile test report,and the relevant calculation parameters of the finite element model were obtained.2.This article through to the CFG pile composite foundation to establish the three-dimensional finite element model,the analysis on the settlement of single pile under the pile type uniform cloth,it is concluded that the settlement for common butterfly settlement,the settlement of raft in the middle area is the largest,to the edge of raft decreases,and the traditional single pile composite foundation of pile type cloth will produce larger uneven settlement,the preliminary several optimization schemes is put forward.3.On the premise of meeting the requirements of bearing capacity,flexible cement-soil piles are used to put forward various adjustment schemes for piles in different parts,such as raft central pile,side pile,corner pile,etc.,and finite element model analysis is established respectively.(1)several different schemes were put forward in the analysis of the central part of the raft.According to the finite element analysis,when flexible cement-soil piles were arranged in the central part of the raft,the uneven settlement tended to decrease first and then increase with the increase of flexible piles in the central part.When the control area of flexible pile is about 20%,the uneven settlement decreases by 19%.(2)when only CFG pile with short side of raft is adjusted,when the flexible pile is gradually adjusted to the center from short side of raft,the uneven settlement of the whole raft decreases first and then increases.When the control area of flexible cement-soil pile is about 40%,the uneven settlement can be reduced by about 25% at most.When the short side of the raft is replaced with a few flexible piles at the same time,the flexible pile is replaced gradually from the edge of the raft to the center,and the uneven settlement is also reduced first and then increased,that is,when the control area of the flexible cement-soil pile is about 60%,the uneven settlement is reduced by about 38% compared with the single pile.(3)replace the flexible pile at the corner of the raft.When the adjustment range of the corner is about 10%,the settlement change is very small.When the Angle adjustment range is about 45%,the uneven settlement is reduced by about 25%.4.Combined with the project of kaifeng Jin Mingzhong learn office building,this paper puts forward four kinds of optimization scheme,and the finite element model is set up respectively were analyzed,and the draw for the rectangular foundation,long and short while in piles at the same time can decrease the uneven settlement of foundation,according to the change of cement-soil pile after pile of control area accounts for about 60% of the area of the whole raft,on the basis of the area ratio,combined with rigid pile raft long side cloth pile length range of raft ratio is about 0.53,the total length of long side raft short of short rigid pile fabric range and proportion of the total length of 0.6,can get a decrease the uneven settlement effect is good and soft cloth pile composite foundation pile.