Research And Application On Pile Foundation Filling Pile And After Pouring Raft Combination To Strengthen Existing Building

With the increasing of high-rise buildings in major cities, the accident of existingbuildings foundation bearing capacity insufficient and building tilt has been happened. Tiltof the existing buildings is top most of the pile foundation, when building foundationbearing capacity is insufficient and produce tilt need to filling pile reinforcement andcorrective measures. The mainly job of this article is discuss after pouring raft used infilling pile reinforcement and correct tilt of existing building.Analyzed the reasons，harm and processing methods when existing building occur tilt.When the spacing of filling pile is less than specification requirements and using differentpile type, combine with using sweeping slightly mesh of ABAQUS software and considerthe constitutive model of soil and pile and raft, material nonlinearity of soil, pile and soilcontact nonlinear and balance on the basis of initial ground stress, researched the influenceof settlement control about before and after filling pile, the pile stiffness, the elasticmodulus of soil and the length of the pile. Through the study found that after filling pile,improving the soil between piles and elastic modulus of pile endpoint soil can effectivelyreduce the foundation settlement. To fill short pile is not apparent for settlement control, itcan makes a ideal effect when the length of filling pile is about2times the original pile.We can found that after the correction of after pouring raft can significantly reducethe maximum settlement of foundation by establish three-dimensional finite elementmodeling in more pile caps. It can reduce the maximum subsidence foundation of30%to40%. Research the influence of raft stiffness control settlement by changing different raftthickness to change the raft stiffness, we can found that when raft thickness take600-1000mm can make maximum settlement reduced most obvious，it can also improvethe foundation bearing capacity. Increasing raft thickness blindly does not have very goodeffect will cause unnecessary waste.According to a project of the pile foundation filling pile and rectify by existingbuilding the author participate in, it has obtained the good effect of reinforcingrectification after poured600mm thick raft, reference for engineering practice.