Safety Analysis for Construction of Building Structures in Close Proximity to Existing Tunnel

As a core component of urban public transport, rail transit must meet very strict requirements for operational safety. Constructing houses over an operating subway tunnel will result in changes in structural load. Improper design and construction would have bad social implications from structure cracking to tunnel collapse. In the context of Cangbai Road Community Building Project in Chongqing, analyses are performed of the performance of existing Line 6 section tunnel and Yuzhong connecting tunnel under axial force and bending moment and deformations of surrounding ground and structure during the project construction to assess the safety implications of the building structure on the existing tunnel structure underneath. The results show: the rail tunnel experiences a maximum horizontal displacement of 0.93mm and vertical displacement of 3.87mm during construction of the community building; after the community building is completed, the verified sectional factor of safety is 2.9 and maximum crack width is 0.18 for Yuzhong connecting tunnel and the sectional factor of safety is 3.0 and maximum crack width 0.11 for the rail tunnel, meeting specified control requirements. Through strict construction control and intelligent monitoring measurement, main structure of the project has been completed without inducing any rail safety accident. The successful development of this project provides helpful experience to similar projects and more reference for multi-purpose development of urban land.