Study On Schemes And Applied Technology Problems Of Metro Stations Constructed With Shield-driven Method And Mining Method

In urban metro construction in china, the shield-driven method is only utilized currently to construct interzone shield tunnels, whose cross section is very simple circle and whose diameter is about 6.0m. Due to lacks of the apparatus capacity and experiences in design and construction for shield tunnels, the shield-driven method is not used directly or indirectly in constructing metro stations and special sectional tunnels, such as connecting line tunnels and transecting line tunnels and back-turning line tunnels and so on. Hence, such a present status has no doubt to limit the extensive application of the shield-driven method. In order to enlarge the applied scope of the shield-driven method in urban metro construction, in the meantime, improve the construction quality and shorten the construction period, the project cost is reduced consumedly on the whole. Based on the matter of fact on the shield technology in China, it is very necessary to study the design and construction technologies of the metro station and special section tunnels constructed with the shield-driven method and mining method.Based on the design principle, technical standard and geologic parameter of Linhe West Road Station in Guangzhou Metro No.3 Line, schemes of building metro stations with the shield-driven method and mining method were put forward. By using similar model test and 2D and 3D Finite Difference Method (FDM), the feasibility and reasonable forms and vital parameters of main structure were researched for triple-arch and double-arch stations constructed with the shield-driven method and mining method. Then, the dynamic variation process of the ground surface settlement and the stress change of the stratum and segment lining were investigated in course of expanding construction. In the meantime, the stress characteristic of main structure and the load magnitude acting on the main structure for double types of stations were studied in the construction. Moreover, the reasonable expanding construction scheme and reinforcing measurement are proposed. Main research findings as follows: 1. The basic construction clews and specific schemes are brought forward for the triple-arch and double-arch metro station constructed with the shield-driven method and mining method. Moreover, the forms of main structure and typical expanding construction steps are designed. Then, the special segment lining and supporting system are developed.2. The similar model test on the construction process of building the triple-arch and double-arch metro station with expanding interzone shield tunnel is carried out by using geometry similarity ratlo C_L=30. The results show that it is feasible to build metro stations with the shield-driven method and mining method. Moreover, the reasonable expanding construction schemes are achieved, and the reinforcing measures and scope of advanced support, during expanding construction are put forward.3. Based on Load-structure Model, the mechanical model which is utilized to simulate the main structure of the station in design and computation is established. In the meantime, the reasonable form and vital parameters of main structures of triple-arch and double-arch station are researched by using FEM (Finite Element Method).4. The dynamic variation laws on the displacement field and stress field of the stratum due to expanding construction are investigated by using the similar model test and numerical calculation (2D and 3D FDM). The form and width and maximum value and its location of ground surface settlement curve are gained. In the meantime, the effect to ground surface environment in construction is appraised.5. The load magnitude acting on the main structure for double types of stations is elicited after expanding construction. The variation of intemal force of segment lining and stress characteristics of the main structure are analyzed when constructing. In the meantime, that whether the lining satisfies design demand or not is evaluated for double types of stations. Moreover, the treatment measures of station structure and reinforcing suggestion are put forward in designing.