A Simplified Calculation Method for Vertical Displacement of Shield Tunnel Caused by Adjacent Excavation
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ORIGINAL PAPER
A Simplified Calculation Method for Vertical Displacement of Shield Tunnel Caused by Adjacent Excavation Xu Riqing . Shen Shuo . Dong Mei . Cheng Kang
Received: 19 June 2020 / Accepted: 28 October 2020 Springer Nature Switzerland AG 2020
Abstract Existing tunnels are typically distorted when excavating an adjacent tunnel pathway, affecting serviceability and safety. To explore the vertical displacement of adjacent tunnels, a simplified calculation method is proposed in this paper. Firstly, the typical displacement mode of a tunnel under excavation is analyzed. To find the principal factors, the importance of factors are ranked by the random forest algorithm based on collected history cases. By statistically analyzing the principle factors, a semi-empirical formula that is relatively simple and convenient for engineering practitioners is proposed. It can be directly used to predict the maximum vertical displacement of a tunnel due to adjacent excavation. The accuracy and applicability of the proposed empirical formula is verified by comparison to field monitoring data of several project cases previously published. Based on the proposed formula, the range of effect of excavation on the tunnel is analyzed, and the results can provide theoretical guidance for similar projects.
Xu R. Shen S. Dong M. (&) Cheng K. Research Center of Coastal and Urban Geotechnical Engineering, Zhejiang University, Hangzhou 310058, Zhejiang, China e-mail: [email protected]
Keywords Geotechnical engineering Excavation Shield tunnel Vertical displacement Case histories List of Symbols H Depth of the excavation, unit m W Length of excavation perpendicular to the tunnel axis, unit m D Length of excavation parallel to the tunnel axis, unit m h Distance between the tunnel crown and the formation level, unit m Ht Thickness of the soil coverage of the tunnel, unit m Lwt Horizontal net distance of the retaining structure and tunnel structure, unit m dw Maximum horizontal displacement of the retaining structure, unit mm type The type of retaining structure type(r) The type of reinforcement Hw Depth of the retaining structure, unit m B Thickness of the retaining structure, unit m EI Stiffness of the retaining structure, unit KN m2/m A Cross angle of the tunnel and excavation, unit degree dy Maximum vertical displacement of the shield tunnel, unit mm
Xu R. Shen S. Dong M. Cheng K. Engineering Research Center of Urban Underground Development of Zhejiang Province, Hangzhou 310058, Zhejiang, China
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Geotech Geol Eng
1 Introduction With the gradual acceleration of urbanization, the development of underground space for urban rail transit networks is at an unprecedented peak. The implementation of the transit-oriented development model has promoted the construction of commercial centers and residential areas adjacent to metro areas, and as a result, the number of construction activities has significantly increased. The excavation of a new build is likely to affec
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