Applicatio N Of Micro Steel Pipe Pile In Inclination Correction And Reinforcement Of A High-rise Building In Loess Filling Site With Large Thickness

Building rectification and reinforcement is a difficult and comprehensive engineering technology,especially for high-rise pile foundation buildings.Miniature bearing capacity of pile with small diameter,higher many advantages is widely used in building rectifying inclined reinforcement,but in most full tilt reinforcement construction process,only limited to the use of miniature pile foundation reinforcement,foundation reinforcement and rectify leaning process structures often independently,this leads to increase in the number of safety factors influencing the construction process,quality and safety control is difficult,the project cost is on the high side.In view of this,based on a top of lanzhou city,gansu province rectify leaning building reinforcement engineering,pile foundation of the structure of the tilt reason,the micro steel tube pile underpinning the feasibility of in-depth analysis and research,through the micro steel tube pile vertical bearing capacity of single pile tests eventually determine remedy pour reinforcement design scheme,finally adopted a new type of cut pile landing rectify leaning process,used in the process of landing the micro steel tube pile for foundation reinforcement to underpinning of the upper structure load,through limit device adjust the sedimentation rate and settlement size,full tilt of the building to the success of the centralizer.This paper mainly studies the application of micro pile in the rectification and reinforcement engineering from the following aspects:(1)Analysis of tilting reasons and preliminary determination of settlement schemeThrough the observation data,the tilt rate of the building is calculated,and the reason of the building tilt is analyzed in combination with the geological survey report,field survey and settlement calculation.The main reason is: the pile foundation of the building did not meet the design requirements of the holding layer;The number of pile foundation is more in the north than in the south,resulting in uneven bearing capacity distribution.The advantages and disadvantages of the two methods of forced landing and jacking were compared and analyzed.Compared with the method of forced landing,jacking correction of the jacking method was of great difficulty,high cost and great damage to the original structure.Finally,it was determined to adopt the method of forced landing and rectifying and righting the building.(2)Study on the feasibility of micro steel pipe pile underpinningThe bearing capacity of the miniature steel pipe pile is analyzed and calculated according to the three aspects of material damage of pile body,pile lateral friction resistance and stability of pile,and it is concluded that the micro-steel pipe pile will not cause instability failure in the foundation of this rectification project.At the same time,Abaqus software was used to carry out numerical simulation on the static load test of micro steel pipe pile,and the simulation analysis results showed that the bearing capacity of micro steel pipe pile was relatively low,so it is necessary to conduct further research through the vertical bearing capacity test of single pile on site.(3)Research and data analysis of vertical bearing capacity of single steel tube pileFirstly,the elastic modulus of the concrete members of the miniature steel tube was obtained through the indoor cement net slurry elastic modulus test and the axial compression test of two 1-meter short columns.Secondly,the static load test was carried out on 3 miniature steel tube cement piles,and the characteristic value of vertical compressive bearing capacity of the three miniature steel tube cement piles was obtained to be 1250 kN.The relationship between pile top settlement and pile body compression was analyzed and discussed through the calculation of test data,as well as the value of comprehensive coefficient in the standard calculation method.Finally,it is concluded that the bearing capacity of the micro-steel pipe pile meets the design requirements,which can reinforce the building on the original base and the building structure with little interference.(4)The application and research of the miniature steel pipe pile in the reinforcement scheme of rectifyingThe working procedure of building rectification and reinforcement and the basic principle of strengthening foundation with micro-steel pipe pile are described in detail.A new method of controlling forced landing and rectifying is adopted in the forced landing and rectifying of buildings.The successful rectifying of this high-rise building provides further theoretical support and basis for the extension and application of the miniature steel pipe pile in loess area.The successful application of the miniature steel pipe pile to the forced landing and rectifying is a successful case for reference in the future.