Construction Technology Of Shield Tunnel Through Existing Railway

The rapid development of urban underground works brings about inevitably more and more shield tunnel construction projects under the existing lines. Due to the high standards of the normal operation demands about line tracks of the existing railways, the displacement and subsidence of surface railway lines must be strictly controlled during the tunnel construction process. This article is based on the Shumuling shield tunnel of the CZT intercity rail which is under construction and through the Beijing-Guangzhou railway project. By using the theoretical analysis, numerical calculations, field tests and other methods, a systematic research on control technologies during construction of Shield Tunnel through existing lines is studied. The main contents are as follows.(1)Using numerical methods, the surface settlement is analyzed with factors of the surface grouting, shield tail grouting quality during the construction process and others. Surface grouting measures could well control the settlement of the existing railways due to the shield on crossing projects. The quality of tail grouting affects the surface subsidence significantly, so it should be strictly ensured during construction.(2)This article has a depth study of the methods and construction technology of surface grouting operations under the conditions of existing lines. By further field grouting tests, it determines the final grouting parameters of the surface grouting materials, grouting mix, grouting pressure, grouting speed and so on.(3) According to the tunnel depth and geological conditions of scene under Beijing-Guangzhou railway, the specific tunneling parameters of Shield Tunnel Construction Turkey cabin pressure, driving speed, tool penetration, cutter speed and others are determined during construction by computational analysis and field tunneling trials.(4) Based on the designed railway monitoring and measuring requirements and control standards of the railway shield, standards for the monitoring and control of the project has been optimized through repeated discussions. It adds groundwater level observation, catenary power base bed columns settlement observation and settlement observation, also determines the existing line monitoring and control standards for each project for further safety of the train operation.(5) Field monitoring and feedback is important means of ensuring tunnels and surface existing line operational safety. It determines the specific monitoring methods throughout the construction process by field practice. And the field monitoring results demonstrate the reliability of the tunnel shield construction parameters and railway technology solutions of this project.