Abstract
Based on the close undercrossing of the existing Line 3 by the Jiucheng ventilation shaft—Chengxin Avenue station section of Nanjing Metro Line 5 TA01 bid, this paper introduces a series of targeted measures implemented during shield tunneling through soft strata under the condition of poor deformation of the existing tunnel. These measures not only ensured that the settlement of the existing tunnel met the requirements, but also guaranteed the safety and quality of the newly formed tunnel itself. Furthermore, it provides a targeted summary of the advance parameters during the undercrossing process, along with a comprehensive analysis of the settlement data of the existing line tunnel, thereby offering an effective reference for the setting of construction parameters in future undercrossing projects involving existing lines in soft strata in the Nanjing area.
Full Text
Shield Tunneling Control Technology for Close-Distance Underpassing of Existing Lines in Soft Ground
Yan Fang¹
¹Shanghai Tunnel Engineering Co., Ltd., Shanghai 200000, China
Abstract
Using the close-distance underpassing of the existing Line 3 by the Jiucheng Ventilation Shaft–Chengxin Avenue Station section of Nanjing Metro Line 5 (TA01 contract section) as a case study, this paper describes a series of targeted measures implemented during shield tunneling in soft ground where the existing tunnel exhibited poor deformation characteristics. These measures successfully ensured that settlement of the existing line met specified requirements while simultaneously guaranteeing the safety and quality of the newly constructed tunnel. Furthermore, the paper summarizes the tunneling parameters employed during the underpassing operation and presents a comprehensive analysis of settlement data from the existing line tunnel, thereby providing valuable reference for construction parameter setting in future underpassing projects involving existing lines in soft ground conditions in the Nanjing region.
Keywords: soft ground; close-distance; orthogonal underpassing; settlement of existing line; parameter analysis and setting