Research On Influence Mechanism And Reinforcement Measures Of The Adjacent Bridge Piles Affected By The Construction Of The Long-Distance Overlapped Shield Tunnels

Metro tunnels are generally laid along the main roads of urban traffic.Due to the limitation of routing and adjacent buildings(structures),metro tunnels are often arranged in a overlapping manner.As well as the superimposed effect of surrounding buildings(structures),it will have a very adverse effect on construction safety.The thesis relies on the shield tunnel between Wanshousi Station and Suzhou Bridge Station on Beijing Metro Line 16.This project is limited by the adjacent Suzhou Bridge and adopts a long-distance overlapping arrangement.It is 1.6m;the tunnel of the entire overlapping section crosses the Suzhou Bridge along the longitudinal side,and the minimum clear distance between the shield tunnel and the bridge pile is only 4.58 m.It mainly analyzes the influence of the tunneling of the upper shield tunnel after the overlapped section on the existing lower tunnel and the reinforcement measures,and the impact of tunneling of the shield tunnel on the adjacent bridge piles and the reinforcement measures.The research content and results include:(1)Using the method of numerical simulation,a three-dimensional calculation model is established for the three typical overlapped sections of the shield tunnel in the interval,and the influence of the advancement of the upper shield on the stratum and lower tunnels has been analyzed.The study shows that the construction disturbances caused by the advancement of the upper shields in different overlapping sections are also different;when the later constructed upper shield enters the scope of its construction impact,the deformation and stress of the segment structure of the lower tunnels of the three overlapping sections have been built The change values are relatively large,and corresponding reinforcement measures must be taken.(2)In order to effectively control the impact of the construction of the upper tunnel of the overlapped section on the segment structure of the tunnel that has been built in the lower layer,a numerical simulation method was used for the comparative analysis of different reinforcement conditions to determine the "interlayer between the two tunnels.Grouting reinforcement,and set steel reinforced measures in the lower shield tunnel.(3)Study the rationality of the reinforcement measures taken on site through on-site monitoring methods.The monitoring results of the section steel support and segment stress show that the reinforcement measures of the grouting in the soil layer and the section steel support can ensure the construction safety of the overlapped tunnel,and the layout plan of the section steel support in the lower tunnel is optimized according to the monitoring results.(4)The numerical simulation method is used to study the variation law of various deformation control indexes of the bridge under the influence of the construction of the intermittent overlapping shield tunnel.The calculation results show that the maximum differential settlement of the adjacent pier columns along the bridge direction and the cross bridge direction is beyond the control Standard,effective reinforcement measures must be taken to control the deformation of the bridge pile.After comparing the schemes and combining with the actual conditions on the site,we proposed and implemented the reinforcement measures for the diagonal grouting of the soil between the tunnel and the bridge pile in the tunnel,and deformed the bridge pier column at the stage of passing through the bridge pile on the shield side The monitoring was carried out and the results showed that the oblique grouting reinforcement measures had a significant control effect and ensured the safety of the adjacent Suzhou Bridge during the crossing phase of the overlapped shield tunnel.