Chengshi guidao jiaotong yanjiu (Apr 2024)
Study on Structural Stability of Shield Launching and Crossing Existing Metro Line in Water-rich Sandy Stratum
Abstract
Objective In geological conditions with water-rich sandy stratum, research on the structural stability of existing metro lines with new metro line shield launching crossing is relatively scarce. It is essential to summarize relevant patterns for similar projects. Method Leveraging the structural engineering of shield launching crossing the existing Line 2 at Huanghe Yingbinguan Sta.-Yingcai Road Sta. interval on Zhengzhou Metro Line 7 as basis, according to actual working conditions, a 3D numerical model of the constructed interval is established using finite element software MIDAS GTS NX, and simulation results for the project corresponding model are obtained using the software result-extraction function. Two monitoring points are selected at the site, and the field-monitored values of them are compared with the simulated values to confirm the model accuracy. On this basis, the influence on existing metro line structural stability under shield launching and conventional under-passing two tunneling methods are further studied. The influence of four values of the vertical distance d between launching portal and existing metro structure is explored. Result & Conclusion The established 3D model, to a certain extent, reflects the actual working conditions. Keeping factors such as the structure, material, and reinforcement method of the existing metro line unchanged, the structural stability of existing metro line varies depending on the tunneling methods. Compared to conventional under-passing construction method, the shield launching crossing causes less influence on the existing metro line structure. When this method is adopted, different d values cause different degrees of impact on existing metro line structural stability. In the case of d=2.00 m, its influence on existing metro line structure is minimal, and the engineering cost is relatively low. It is recommended to adopt shield launching under-passing method under permissible engineering conditions, and the suggested value is d=2.00 m.
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