Numerical Simulation Research On Differential Settlement Of Long Tunnel Under Complicated Geology Conditions

Differential settlement is one of difficult problems in international geotechnical engineering. Differential settlement of long tunnel under complicated geology conditions is not only very complicated, but a problem which is crying for solving in project and theory.In this paper, combined connecting engineering project at Shenzhen of Shenzhen-Hong Kong Western Corridor, differential settlement of long tunnel is researched. This project is important part of Shenzhen-Hong Kong Western Corridor and special road passing through the territory of Shenzhen-Hong, which mainly adopts complex road structure. In the ground by filling sea of the project, conditions is very complicate and foundation treatment has many forms. Therefore, based on the domestic and foreign research status quo about differential settlement of tunnel, aiming at differential settlement of long tunnel under complicated geology conditions and combined incremental-iterative method of balance equation in non-liner finite element, differential settlement is researched, in order to provides gist for design and construction of the project. The research work here mainly includes:(1) Theory of consolidation settlement is applied in discussing the calculation method of stratum consolidation settlement. The domestic and foreign calculation method of instant settlement is summarized. The primary calculation method of consolidation settlement is expatiated, including the theory of linear elasticity consolidation, non-linear consolidation settlement characteristics of soils and calculation of final consolidation settlement of stratum, which establishes foundation for finite element analyse.(2) On the basis of the numerical simulation theory of stratum settlement, this paper discusses analysis method of non-liner finite element of consolidation settlement of stratum and more elucidates solutions of time step and iterative convergence in numerical calculation. Considering consolidation equations in common use, solving process of BIOT consolidation finite element is given. Based on Mohr-Coulomb rule, finite element of soil is discussed. Furthermore, the key approaches and technology problems of the finite element modeling process, including model parameters, boundary conditions, contact element, initial stress state and life-death element, which provides gist for specific numerical simulation and analyse.(3) Based on the theory of finite element and fully consideration of complicated geology conditions, under two-dimension and plane-strain condition, the numerical simulation methods of different soil models are given, including reinforced concrete case structure, pile, composite foundation and reinforced earth. According to characteristic and mechanism of different pile types and composite foundations, specific methods is elucidated in this paper. Basic principle about numerical simulation of pit excavation and a series of problems about numerical simulation pit backfilling is also given. Considering different working conditions, this paper discusses emphases aspects of numerical simulation in differential settlement of long tunnel, which establishes foundation for final numerical simulation.(4) Case calculation and analysis is made on long tunnel of Shenzhen-Hong Kong Western Corridor Project with the numerical simulation theory and method in differential settlement of long tunnel under complicated geology conditions and ADINA software in this paper. The numerical simulation in differential settlement of long tunnel under complicated geology conditions has been reasonable and validated.