| With the wide development and utilization of cities’ underground space in China, especially the rapid planning and construction of the subway tunnel in cities, various complicated problems in adjacent excavation come into being. To ensure a smooth progress of the construction project, the structure security of adjacent buildings, as well as their proper functioning should be guaranteed. Therefore, to minimize the influences on existing buildings and underground pipelines, to ensure the construction safety and to achieve the highest economic profits, what technology and auxiliary methods should be adopted in the construction process, and how to effectively predict and prevent the occurrence of sedimentation and collapse, are urgent problems to solve.Against the background of Shenzhen metro line 7 that pass closely underneath the existing line 4 station project, theoretical research, the finite element numerical analysis and the numerical simulation based on the analysis of subsidence monitoring method, the calculation model was established based on scaled finite element analysis software ADINA, and the full face grouting reinforcement and CRD straight wall dig beneath the existing railway station construction scheme are studied by numerical simulation. By analyzing, quantifying the various risk elements exist in the construction process, it aims to provide a theoretical basis and reasonable prediction framework for the smooth implementation of similar project.The main contents are as follows:1. Due to the fact that the actual construction project is in its preliminary stage when this thesis is drafted, and also the lack of measurement data, this study focuses on the theoretical prediction and risk assessment of the underneath adjacent construction plan, engineering difficulties and related factors; and some countermeasures are also proposed. Combining actual geological survey data and using engineering analogy method the material parameters of reinforcement area are determined, and the values of which are tested via ADINA finite element software simulation.2. On the basis of a large number of numerical analysis methods and research results of the settlement mechanism, and a full consideration of the selection of related parameters and corresponding measures of the reinforced region, a response analysis of adjacent excavation and construction to existing railway tunnel was made via numerical simulation.3. According to the empirical formula of Peck and related theory, the settlement of tunnel excavation formation, i.e. the settlement curves can be expressed via the normal distribution curve; and with the excavation of tunnel, the ground settlement will tend to become stable, and this theory can be used as the criterion of rationality of simulation test data.4. The underneath adjacent CRD excavation and construction scheme was simulated via the finite element analysis software ADINA. According to the construction scheme of the excavation sequence is clearly defined and unit construction step with definitions of life and death, through the different excavation, excavation of existing railway station structure factors of settlement deformation and safety operation is analyzed and forecast; Simulation calculation shows that the maximum sedimentation value of existing station floor is 0.45 mm which is less than the control value; it can meet the basic accuracy requirement, and the largest convergence value of early lining roof is 0.80 mm, which is less than the control value, indicating that errors exist in the simulation results; the simulation results demonstrates the overall response of the theory is generally in line with the reality. |
PDF Full Text Request