Impact Analysis Of Nearby Viaduct Shield Tunneling

As the speed of urban construction accelerates,To alleviate traffic congestion,metro has become the primary means to ease urban traffic congestion.Shield tunneling inevitably result in disturbances to the surrounding rock,in severe cases,damage to the building may even affect its normal use.Through theoretical analysis,numerical simulation,in-situ monitoring,etc.this paper analyzes the influence mechanism and influence factors on surrounding rock during shield tunneling,and the analysis of the influence factors on the neighboring pile foundation during the shield tunneling process.This paper uses the finite element software MIDAS GTS to simulate and analyze the working conditions of the Qian Gao section of Hefei Metro Line 4,research and analyze the actual in-situ monitoring data of the working condition,by comparison,the influence of the driving distance on the surrounding rock disturbance and the pile foundation of the adjacent viaduct is obtained.Get the following conclusion:(1)soil settlement law and the five stages of vertical settlement are analyzed when the single and double-line shield construction disturbs the soil.settlement trough of the soil tends to be normally distributed in the case of a single-track tunnel.however,soil settlement trough of the double-track tunnel has many forms of influences such as the depth of the covering soil,the distance between the tunnels,and the diameter of the tunnel.stages of large vertical settlement are mainly the passing stage of shield equipment and the later stage of consolidation settlement.(2)The distance between the excavation position and the pile group affects the growth rate of surrounding rock settlement.construction phase of Ring 20-Ring30,growth rate of settlement of surrounding rock is the largest compared with other stages.(3)When the same soil depth,when the ratio S/D of the distance between the double lines S to the outer diameter D of the tunnel,when S/D>2.3,surface settlement trough slowly transformed into a "W" and "double V" shape.When S/D<2.3,ground subsidence approximately normal distribution curve.(4)Within ± 20 circle excavation range at midpoint of tunnel excavation direction,main growth rate of pile deformation mainly comes from the tunneling of the first 20 rings,growth rate of pile foundation deformation caused by shield tunneling of the last 20 rings is very low.In addition,closer shield tunnel is to the position of the pile group,the greater the growth rate of the pile group’s deformation.Figure 26 table 12 reference 50...