Study On Calculation Method Of Foundation Settlement Of Karst Tunnel Reinforced By Pile Foundation

In recent years,the rapid development of high-speed railway in southwest,the inevitable in the mountainous karst geographical environment construction of the tunnel,karst geological hazards to the safety of tunnel construction,safe operation pose a serious threat.Due to the variability and karst tunnel location,as well as the size of the karst variability,caused the complexity of karst influence on tunnel basement subsidence,and the existing research on karst tunnel remains to be further deepened.To this,this article will take the yunnan-guizhou high-speed changqingpo in karst tunnel as the research background,karst,tunnel and pile reinforcement of 3 d model,using FLAC3 D numerical simulation,study filling karst under the condition of different size and different position,the influence of foundation settlement of pile foundation reinforcement of karst tunnel,and analysis of the regularity,according to the calculation data,combined with the existing formula for karst tunnel foundation settlement calculation method is put forward.Main research work:(1)after examining the existing data on the basis of research on karst,in yunnan-guizhou high-speed changqingpo in karst tunnel as the research background,analysis of karst cave and the tunnel,the space position of the relationship between karst boundaries as classification basis,to a reasonable classification of karst tunnel,three-dimensional calculation model is established.(2)use FLAC3 D numerical calculation software to analyze and analyze the settlement effect of karst boundary on the tunnel basement before and after the pile reinforcement tunnel.The influence of karst boundary on the settlement of tunnel foundation and the change of foundation settlement are analyzed.In the case of pile reinforcement in tunnel,the settlement variation law of foundation of karst tunnel is analyzed,and the reinforcement effect of pile is analyzed.(3)the parameters of the reinforced pile are studied in the case of maximum karst range.The single-row pile number of pile foundation,longitudinal spacing of pile and diameter of pile are studied by single variable method,and the influence of the change of pile foundation parameters on the settlement of tunnel basement is analyzed.(4)according to the results of numerical calculation,studied and analyzed the existing foundation settlement formula,is put forward to karst border settlement calculation for variables,using the data fitting software,set up four kinds of cases with karst boundaries as the variable function calculation formula and the influence of pile foundation parameters calculation formula of the coefficient of function,and the formation of the corresponding calculation flow chart.The practical engineering cases are selected,and the calculation results are compared with the actual design,and the rationality of the calculation method is verified.