Application Of Discontinuous Contact Computational Model In Mechanical Behavior Of Shield Lining

Because of the limitation of city land in our country and the requirement of the three-dimensional city traffic, the development and utilization of underground space has been the primary task in modern city. Meanwhile, high efficiency and dense function of modern city require more precision during engineering construction. Shield method has become the main construction method in urban underground engineering, which has little influence on the surrounding environment and high automation in construction. So the study for the design of shield lining is very valuable for academy and application, which has some guidance for designing shield segment in the aspects of security, rationality and economy.The permanent supporting structure in shield tunnel is shield lining, which is the key part and the focal design point in whole shield tunnel. Now, the biggest difference between common design methods of shield lining is different assumptions on segment joint. Because the joint has different forms, the selection of joint parameters has an enormous effect on calculation results. The common design methods of shield lining all assume the reinforced concrete segments as elastic body. But the concrete material has different strength and rigidity characters under the compressive and tensile stress. Especially, when the tensile stress of concrete is larger than the design value, there will be micro-cracks on the area of tensile stress. So the design model of shield lining must consider the concrete material characters. During the shield tunnel construction process, segment structure show exceptionally complex mechanical property, which influence by construction factors such as assembly process, grouting pressure, jack forces and tunnel longitudinal discrepancy settlement. How to reasonably and effectively assess the influence of mechanical properties of lining segment by shield tunnel construction process still is one of the difficult problems in lining design work and construction. The main research as follows:1. On the base of analysis on the common design methods of shield tunnel lining, a new discontinuous contact computational model of shield tunnel lining is built, which use by finite element software and can accurate simulate the interrelationships between bolts and segments. And it gives a detailed presentation of the calculation principle of nonlinear contact problem.2. In order to verify the rationality of the discontinuous contact computational model, using field test and numerical simulation calculation method to research the force and deformation of shield lining. It gives a detailed presentation of the contents and results of field test. And the calculation equation of internal force is derived, which based on the harmonious relation between the inner side rebar strain, the external side rebar strain and pressure area concrete strain, and equilibrium relation of force and bending moment on section.3. Using load-structure calculation method, study the force and deformation characters of shield segment in discontinuous contact computational model method, elastoplastic-damage model method and routine method model. It obtains the strength and rigidity characters of concrete material under the compressive and tensile stress, the micro-cracks caused by structure damage, the similar and dissimilar characteristics between3models.4. Using soil-structure calculation method and discontinuous contact computational model, study the influence of shield segment by tighten degree of bolts, non-uniform grouting behind lining, and existing dislocation on longitudinal joint. Through simulated results and measured datas, it can draw same conclusions of stress and deformation law of shield segment caused by every irregular construction operation.