Research On Rectification And Reinforcement Mechanism And Key Technology Of High-rise Buildings In Western Region With The Special Geotechnical

With the rapid development of economic and society,high-level,high-rise buildings,due to the tension of urban land,some buildings had to be located on the special geotechnical foundation,and cause the accidents of building tilt happen now and then.This article rely on the engineering case of rectification and reinforcement of two high-rise buildings that is located in loess foundation and weakly expansive and strongly weathered mudstone foundation in the western region,and through systematic analysis of rectification mechanism and corresponding reinforcement mechanism of horizontal forced settlement and vertical forced settlement rectification method by field test,monitoring method,theoretical analysis,numerical simulation and so on.The main contents are as follows:(1)Investigation and analysis on the reason of the inclination of the building,six types of factors that may cause building tilt summed up,such as man-made design mistakes,improper construction,improper use and maintenance,the influence of foundation geology environment,the influence of surrounding environment and the influence of natural disasters.At the same time,combined with the engineering case,analysis of the reasons for the tilt of building 1 in a cell in Dingxi and B11 building in a cell in Xining,and find out the two floor tilt of the adverse factors,to lay the foundation for further mechanism analysis;(2)The analysis on the failure modes of level soil pore forming tells that the mail soil failure mode is the hole edge shear sliding failure,and the middle belt is still for the elastic compressive deformation.And based on Mohr-coulomb yield criterion,the level soil pore forming additional settlement calculation model,soil plastic zone between the hole range calculation formula,and the corresponding critical state soil width calculation formula are all concluded,which can provide the basis for tilt rectification design.At the same time by means of numerical simulation,the numerical analysis was carried out on the key soil parameters.The consistence between theoretical calculation results and the numerical simulation results proves the rationality of the calculation model;(3)Based on the systematical analysis of level soil landing rectify leaning method used on collapsible loess foundation as well as the stress distribution characteristics of foundation soil,gravity center position of building is calculated,and according to the tilt direction,building remedy tilting axis is determined;According to rectify leaning goals,the regional target settlement is determined,and then according to different target settlement,the foundation soil is categorized as landing zone and adjusting zone.landing zone is 1 ? 2 m more than central axis.landing zone is to be soiled out and adjusting zone is to be reinforced.soil pore size should rely on the target volume and the conditions of construction machinery.in the same remedy pour engineering,soil pore size should be fixed and Soil according to target settlement,hole spacing is horizontal soil landing rectifying inclination of the line of control parameters;(4)Systematical analysis on anchor mechanism in horizontal soil landing method has been carried out.Anchor cable pressure does not play a bigger role in the case of less quantity of soil.when soil make stress reaches a critical stress,the influence on additional settlement increases significantly.Therefore,anchor cable pressure should be in critical condition after pressure.(5)Based on the theory of semi-infinite elastic body,mindin solution on vertical soil stresses release stress release theory analysis,draw a single soil cause based on both sides of the additional settlement calculation method,and using the method of numerical analysis for validation,due to the theoretical analysis results without considering the mutual influence of the perforated sequence,the theoretical calculation results than the results of numerical simulation is larger,but overall is consistent;(6)Rectifying inclination of the success or failure depends on whether choke inclined to continue to develop,and at the completion of a full tilt stable,this article in view of the collapsible loess foundation is put forward by adopting the combination of steel pipe pile and lime pile reinforcement method,and based on the theory of cavity expansion theory of composite pile reinforcement mechanism analysis,concluded that lime pile can effectively improve the physical and mechanical properties of foundation soil,to improve bearing capacity of steel tubular piles by 28%,and steel pipe pile and lime pile arrangement method is put forward.At the same time for located in strongly weathered mudstone and sandy pebble foundation outside the building with raft of wisdom of the flexible reinforcement method,avoid the risk of the pile foundation construction causes tilt intensifies,and remain stable for a follow-up.