| Urban development is intensive and high-rise,and the development of urban rails has quickly entered people’s lives due to its environmental protection and high efficiency nowadays.lt is complex in the construction environment of the subway project.The shield method is one of the main ways of tunnel construction among them.Which reduce the disturbance of the shield construction,control the surface deformation and settlement.This article takes the third-phase Wu-Tian interval of Hefei Metro Line 1 as the research object to study the influence of the main factors of tunnel shield construction on the surface settlement status and change trend.Through the data sampling and analysis of the settlement points,the derivation analysis of the Peck formula and the simulation calculation of the FLAC 3D finite difference program,the law of surface settlement changes is obtained,and on this basis,measures to control settlement are proposed.Firstly,the principle of shield against strata disturbance was explained according to the space-time effect theory of stratum.Secondly,the variation rules of surface settlement were summarized according to the monitoring data.and the Peck correction formula adapted to the interval was obtained.Furthermore,the numerical simulation analysis was carried out using Flac 3D software.Based on it,the proposed measures to control the settlement were put forward.The research results of article are as follows:(1)Firstly,based on the theory of space-time effect of stratum movement.The reasons and mechanism of surface subsidence caused by the tunnel shield.Main influencing factors of surface subsidence(2)By collecting and sorting the monitoring data and data of the third phase Wu-Tian of Line 1 of Hefei Metro,the surface settlement monitoring plan was determined and the measured data was analyzed.The results show that the surface subsidence data is within a stable and controllable range.The tunnel excavation in this interval is mainly located in a relatively uniform silty clay layer.The lateral settlement change caused by the excavation process is approximately normal.(3)The regression analysis method was used to fit the monitoring data of the interval to determine the reliability of the Peck regression prediction.Two correction parameter factors were introduced to modify the Peck formula and compare and analyze the measured data of the interval.Finally,the recommended value range of the correction parameter of the Peck formula is obtained:the correction parameter value of the maximum ground settlement Smax is between 0.06 and 0.15,and the correction parameter value of the settlement tank width coefficient i is between 0.6 and 1.1.(4)Based on this shield interval,It is established a simplified three-dimensional numerical.lt use FLAC 3D finite difference software to study the ground settlement law during the earth pressure balance shield construction process,select the three sections of the 3D model when the shield advances to 0m,15m,30m and 45m,pass the shield The contour cloud map,vertical stress distribution cloud map,and vertical displacement cloud map of the soil around the tunnel are analyzed in three aspects to analyze the inflluence of the shield tunneling process on the settlement of the stratum disturbance.Finally,through analysis of simulation calculation results and actual data,and the corresponding control settlement measures are proposed. |
PDF Full Text Request