Control Of Surface Subsidence In Spliy-type Launching

As the development of our economic construction impels China to be more and more urbanized, cities are expanding as well. In this case, people’s livelihood and production depends more on rail traffic. Metro constructions are often undertaken in urban areas, which cause problems between the construction and crucial buildings or living quarters. Effective measures should be carried out to control subsidence of ground adhesion and soil disturbance.This paper mainly focuses on the shield construction of 01 section of Daxing Line, Beijing Subway, from Huangcun Railway Station to Yihezhuang Station. The project is implemented in a small curvature radius of 300 m, going through 12 railways including Beijing-Shanghai railway and Beijing-Kowloon railway, which is facing tough issues in social impacts and construction difficulties. Researches and innovations presented in this the paper are as follows:(1) For the engineering geology and construction drawings of this shield zone, we analyzed the overall hydrogeological condition, surrounding buildings, underground utilities and the soil conditions in this area. And suitable shield equipment is chosen concerning its structure, function, the construction technology involved and other situations.(2) For the cases in the job site, the unearthed shaft can hardly build for the difficulties in adjacent buildings and narrow fabricating yard. However, after analyzing the possible shield launching methods, spilt-type launching will be adopted, and detailed study has been done for the launching process.(3) In the spilt-type launching stage, as it disturbs the soil, emergencies, like instability of shield-tunneling faces, may occur. For this matter, we analyzed the mechanism and rules lying in soil disturbance and set appropriate soil pressure. With the real-time monitoring of the soil pressure in the chamber, the soil pressure in the sealed cabin can be kept in dynamic balance with that of the excavated surface.(4)As for the surface subsidence emerging in spilt-type launching process, correspondent measures and monitoring plans are made. The research analyzes the monitoring data of the rail surface, the ground between rail tracks, deep displacement, rail and ground surface settlement as well as shield parameter. Effective measures are taken to cope with such matters, so that ground surface settlement is controlled in a better manner.