Construction Of Isolation Piles For Adjacen High-speed Railway Viaducts Analysis Of The Influence Of Piers

At present,to ease traffic congestion,convenient for people,countries are developing urban rail transit,the first-line cities are in place for the construction of the subway,the subway construction,a lot of the time would inevitably through high-speed rail viaduct,in order to reduce the influence of shield construction on the pile foundation,the reinforcement measures will be taken,and the construction of the reinforcement engineering of high-speed impact of the pile foundation.In this paper,the isolation pile reinforcement project of an off-line beijing-shanghai high-speed railway viaduct under jinan subway is taken as the background,and the influence of isolation pile construction on the displacement of railway bridge piers and pile foundations is studied through the analysis of field monitoring data and the data of numerical simulation of construction.The main research contents and results are as follows:(1)The review of the domestic and international research status of the influence of isolation pile construction on the stratum and adjacent pier pile foundation is reviewed,and some shortcomings and some problems to be solved in the current research are proposed.(2)The principle of isolated pile construction,the theoretical calculation method of adjacent pile foundation deformation caused by construction,the construction method of bored pile,post-grouting technology and the construction control measures of isolated pile are summarized.(3)Analyze the on-site monitoring data of the displacement of the railway pier and the deformation of the beam caused by the construction of the isolation pile.The results show that the construction of the isolation pile will have the greatest impact on the settlement of the adjacent high-speed railway pier,and the displacement in the horizontal Y direction will be the least,and the deformation of the beam will be synchronous with the pier.When drilling,the pressure and speed of the rig are increased,resulting in collapse in the hole near the pier,and the deformation data of the pier is increased by 0.2 mm.When the outer side of the beam body is constructed,the displacement of the pier is larger in the horizontal X direction(cross-bridge direction).When the beam is under the beam body,the settlement of the pier and the displacement in the horizontal Y direction(shun-bridge direction)are larger.MIDAS-GTS software was used to conduct numerical simulation of the influence of isolated pile construction,and the displacement and deformation of piers,cap caps and pile foundations were analyzed,and the simulated and measured displacement and deformation values of piers were compared and analyzed.The results show that the method of parameter selection in this simulation is correct,and the parameters and model size selection are very reasonable.The horizontal displacement of the pier caused by the construction of isolated piles is the largest at the top of the pier,the settlement of the pier on the side with more isolated piles is large,and the deformation of the pile foundation is in the shape of C.The drilling interval of the isolated pile has obvious influence on the pier and the pile foundation,but when the interval is too large,the displacement change of the pier and the pile foundation tends to be sta ble and no longer decreases.(4)The MIDAS-GTS software was used to simulate the influence of the isolation pile construction.The displacement deformation of the pier,the cap and the pile foundation was analyzed,and the simulated and measured values of the displacement deformation of the pier were compared and analyzed.The results show that the simulated and measured values of the displacement deformation of the piers are basically consistent with the measured values.The method of selecting the parameters is correct.The horizontal displacement of the piers caused by the isolation pile construction is the largest at the top of the pier,and the other side of the isolation pile The settlement of the pier is relatively large,and the deformation of the pile foundation is C-shaped.(5)This paper uses numerical simulation to analyze the influence of four construction processes on the displacement of piers,which are Shi Ji-3,Shi Ji-5,Shi Ji-7 and Shi Ji-5 symmetrical jumping pile construction.It is concluded tha t the settlement of piers varies most in different construction processes.