Research On The Influence And Control Of Deformation Of Piles On Structure By Top-down Method

The construction technology of top-down method has been used more and more widely in the construction of dense urban construction.In the construction of the top-down method,as an important part of the structure and the key link in the construction,the precise positioning,control of verticality and settlement of the support pile is particularly important.At present,most of the research on pile positioning,control of verticality and settlement of pile is still limited to the construction experience,not to the theoretical level,form a complete theoretical system,so there is still need to continue research.This paper combines the construction project of Hunan Wangwang hospital(phase two),and carries out the following research work:(1)By means of formula derivation,the stress and deformation of the structure when pile is normal and pile deviation,deflection and settlement are compared and analyzed.The following conclusions are obtained:when the pile is tilted,with the increase of pile and column inclination angle ?0,pile bearing capacity Pcr,decreased,when the pile inclines seriously,the failure mode of pile is instability of buckling;when the pile deviation occurs,with the increase of pile and column offset ?,the bending moment at pile and column increases as followed,the increased value is 0.375q?2;when the pile sinks,the structural beam and slab will be affected accordingly,resulting in additional deflection and additional bending moment.The values of additional deflection and additional bending moment vary with the settlement of the pile.If the pile subsidence is serious,it will have an adverse effect on the overall structural safety.(2)The influence of verticality,deflection and settlement of piles on the stress and deformation of the structure under various working conditions was studied and analyzed through the numerical simulation method under the action of self-weight load and construction live load,founding that the verticality of the piles has a great influence on the stress state of the structure;the main effect of the pile deviation on the structure is not to increase the overall deformation of the structure,but to produce a greater stress and strain on the piles where the displacement occurs.As for pile settlement,as long as the structural integrity is guaranteed during construction,the small settlement of a single pile has a limited effect on the overall structure.(3)Based on the engineering practice of the project,this paper proposes the process and method to solve the problems of pile positioning,control of settlement and verticality of pile in the construction by top-down method,which can provide references for similar engineering practice.