The Optimization Design Of The Zhengzhou Shield Lining Segments

Zhengzhou is an important transportation hub city in the central region,the fastdevelopment of the city has brought great pressure to the transport. Zhengzhou begin todevelop rail transport vigorously in order to solve the traffic problem. Among them, theshield method become an important method for the construction of the subway because of itsunique advantages. In the Shield Tunneling Method, the shield lining segments are the mainassembly member,they bear the underground soil pressure, water pressure and some specialloads, so they play an important role. The quality of the shield segments is directly related tothe quality and safety of the tunnel, therefore, the design of the segments in the shieldconstruction method is particularly important.But the shield segment has not been very sound shield segment design specifications,each region still learn the design from other cities of the country, this method is oftencontradictory and geological parameters of each city are not the same，and because thegeological parameters and the segment structure parameter of each city are uncertainty. thereis a big difference of the form of reinforcement calculated in the section of segment structure.the rationality of the reinforcement in the actual stress condition of the segment structure cannot be considered fully. So the study on the stress characteristics of the shield segment inZhengzhou and the optimization design of steel have a very practical significance. The papertakes Zhengzhou No.1subway as an example, combined with the formation characteristics ofZhengzhou, the segment mechanical model is established using the finite elementsoftware,through the calculation of the segment loading,analyzes the influence of thedepth,the cohesion,the density,the internal friction angle of soil to the segment stress. Andthe function relationship between the different parameters and the maximum axial, themaximum relative bending moment, the maximum negative bending moment is obtained byusing polynomial fitting.Using the finite element software ABAQUS simulate the shield lining segments withplate reinforcement,beam slab reinforcement，the mechanical behavior of steel and concrete are researched on the basis of strength theory. By comparing the segment mechanicalbehavior with different reinforcement forms, the right reinforcement is obtained.The main reinforcement of less than15meters tunnel lining segment is optimized usingthe stratigraphic structure method. The original diameter25mm of main reinforcement isoptimized for the diameter of20mm. Using the finite element software establishes theoriginal model and the final model, by analysizing and comparing the simulation results ofthe main reinforcement and the distributon reinforcement,it is concluded that the optimizedscheme is feasible and some other reference conclusions.