Study On Surface Settlement Caused By Large Diameter Shield Tunneling

With the coordinated development of Beijing-Tianjin-Hebei transportation integration,the construction of Beijing New Airport Line,S6 Line and Pinggu Line has also been launched one after another.Construction of Beijing Regional Express Line,For the first time,8.8m diameter shield tunneling method was used in the construction of Beijing New Airport Line.Because the shield tunneling method disturbs the soil around the tunnel,resulting in surface settlement and deformation,endangering the safety of ground buildings.Therefore,the study on the ground settlement law caused by 8.8m shield tunneling of the new airport line can provide reference and basis for the follow-up regional express line construction in Beijing.Firstly,the paper summarizes the settlement theory obtained by predecessors,and analyses the law and mechanism of ground settlement caused by shield construction.Secondly,using ABAQUS numerical simulation software to simulate the shield construction process relying on the engineering background,analyzing the ground settlement and its influence scope caused by shield construction.Then,Comparative analysis of numerical simulation data and measured surface monitoring data,and based on the engineering background,the Peck prediction formula for predicting ground settlement caused by 8.8m shield construction on Beijing New Airport Line is deduced.Finally,the control measures to control the surface settlement are briefly described.The research results are as follows:(1)summarizing the settlement theory obtained by predecessors.and using ABAQUS simulation software to simulate the construction process of the Right-Line mileage of a Shield Section on the new airport line of Beijing Rail Transit.The influence range of soil three-dimensional disturbance is analyzed when the shield is buried in silt layer at a depth of about 15 m.The proportion of settlement in the total settlement is analyzed and summarized in combination with the longitudinal settlement curve.(2)Analysis of the Variation Law of Surface Settlement in Lateral and Longitudinal Dimensions by Using Field Data,and Combining the numerical simulation data with the measured surface monitoring data,it is analyzed that the traditional Peck theoretical formula curve is the same as the measured surface settlement data curve in the overall trend,but there are large numerical errors.Based on the linear regression and correction of the theoretical formula,the Peck modified prediction formula for predicting the surface settlement caused by shield tunneling of the new airport line of Beijing Rail Transit is derived.(?)(0.5~0.8 for?;0.6~0.9 for?)(3)This paper briefly expounds the control measures of ground subsidence caused by normal shield tunneling and passing through special sections,and summarizes the technical points and methods of controlling ground subsidence,which can provide reference for the construction of regional line of Beijing rail transit in the future.