Multistage regulation strategy as a tool to control the vertical displacement of railway tracks placed over the building site of two overlapped shield tunnels. (January 2019)

• Record Type: Journal Article
• Authors: Zheng, Gang; Fan, Qi; Zhang, Tianqi; Zheng, Weihong; Sun, Jibin; Zhou, Haizuo; Diao, Yu
• Is Part Of: Tunnelling and underground space technology. Volume 83(2019)
• Page Start: 282
• Page End: 290
• Publication Date: 2019-01
• Subjects: Multistage regulation strategy -- EPBM variables -- Railway tracks -- Overlapped tunnels -- Surface displacement; Tunneling -- Periodicals; Underground construction -- Periodicals; Tunnels -- Periodicals; Underground areas -- Periodicals; 624.193
• DOI: 10.1016/j.tust.2018.09.040
• Languages: English
• ISSNs: 0886-7798

Abstract

Highlights: The article reports a case history of overlapped tunnels passing beneath a running railway zone, in which both the measurement of surface displacement and the record of EPBM operation were presented in detail. Multistage regulation strategy (MRS) was put forward and applied to the control of the surface displacement at the railway zone to ensure the safe operation of the railway lines during the tunnel construction. Prior to tunnelling in the railway zone, trial advance tests were performed at a nearby site with detailed surface instrumentation, which provide the first-hand data for the formulation of MRS. The surface response to the second tunnel (Up-line) was shown distinctly different from that due to the first one (Down-line), and therefore may be of referential significance for other similar projects. Abstract: Constructing a tunnel by means of an Earth Pressure-Balanced Machine (EPBM) requires an appropriate definition of the relevant variables to minimize the environmental impact. Because of the complexities and uncertainties of underground engineering, however, the values of the EPBM variables assumed in the design stage are often inappropriate, and adjustments are required based on in situ observations. In this paper, the Multistage Regulation Strategy is applied to the displacement control during the construction of two overlapped tunnels in Tianjin Metro line 5 underneath a pre-existing railway line, and the EPBM variables are continuously adjusted based on works in progress. The core of the Multistage Regulation Strategy is the so-called target decomposition (as each tunnelling stage requires its control target), which is accomplished based on the tunnelling work at a nearby site (test zone, beside the railway line), whose instrumentation is presented in detail. By rigorously applying MRS, the surface settlements along the railway line passing over the two metro tunnels can be successfully controlled through a step-by-step adjustment of EPBM variables, and the requirements concerning the accumulated surface settlements specified by the current design standards can easily be fulfilled.