Research On Technology For Deep Foundation Pit Nearby Existing Railway Lines Under Complicated Geological Conditions

With the scale of urban metro expanding in China, the technology of metro construction has also been developing rapidly, and the technology of deep foundation pit is an important part. Deep excavation, which mainly consists of supporting, waterproofing, dewatering, excavation, and many close links, is complex system engineering. Meanwhile, deep excavation is one of the most complicated fields of civil engineering technology, which related to geotechnical and structural knowledge and three basic issues in soil mechanics, such as stability, deformation and seepage. Analysis of monitoring data is an important way to conduct deep excavation construction and is also an important means of information construction. Deep excavation works related to the success of the overall construction situation. It is very important to study on the technology of deep foundation fit construction and information construction, and how to ensure the safety and protect the surrounding environment during deep excavation is an important issue.Based on the project of Zhongshan 8th station of Guangzhou Metro No.5 Line, relative study in this dissertation is carried out to discuss the key technologies, such as structural form selection for supporting structure, dewater techniques, excavation and supporting methods, information construction, and surrounding environmental protection measures for deep foundation pits. Against muddy, sandy, hard-soft uneven ground, nearby buildings and structures, and existing railway lines, the reasonable supporting structure plan is proposed to ensure the safety. Monitoring system has been established and the retaining systems has been optimized based on the monitoring real-time data and feedback. And then the information construction is achieved, therefore the deformation of foundation is in control. Moreover, measures have been carried out to ensure the safety of surrounding structures and the existing railway lines. And the experience and relevant construction parameters and have been obtained through construction and monitoring.The result of this dissertation has meaningful conduction to design and construction of deep foundation pit under complicated geological conditions and surrounding environmental protection. Meanwhile the obtained construction parameters and experience can also provide important reference to the correlative projects.