Experimental tests and theoretical analysis for mechanical behaviors of side wall opening construction in mined excavation subway station

Abstract

The connection of subway stations to surrounding underground spaces inevitably involves opening construction in the existing underground structure. The opening construction can strongly impact the existing underground structure when there is no reserved condition. In this study, three-dimensional numerical simulation, model test, and theoretical analysis are used to analyze the mechanical behaviors of side wall opening construction in a mined excavation subway station-Xuanwumen Station of Beijing Subway Line 4. Based on the deformation and stress characteristics of the existing side wall structure, two different reinforcement measures are compared. It is found that the vertical and horizontal deformations of the existing structure caused by opening construction is −1.58 and −1.79 mm, respectively, which are lower than the subway deformation control requirements (3 mm). However, the first and third principal stress increments are 2.14 and −4.62 MPa, respectively, which are markedly higher than the control requirement (10%). A “two-step opening” method is proposed for side wall opening construction in underground structures based on the solution of complex function to the orifice problem. This theoretical method is validated by numerical simulations and model tests, achieving highly consistent results. The allowable ultimate span of side wall opening is 5.75 m without reinforcement. Findings of the present study provide a reference for the design and construction of side wall openings in similar underground spaces.

Analysis of the influence of side wall opening on the arch structure of metro station using the PBA method

“…Wang [19] pointed out that the opening of the side wall would lead to the redistribution of internal forces in the existing station structure, and it was necessary to control the opening size and the clear distance between adjacent openings to reduce the adverse effects brought by the side wall opening. Hu et al [20] analyzed the influence of side wall opening on the force and deformation of station structure and found that the deformation increment met the requirements while the stress increment was higher than the control requirements and suggested that the limit opening span of side wall should be 5.75m when there was no reinforcement. On the other hand, scholars have also studied the influence of reconstruction and expansion construction of existing stations on the force of the original structure and put forward corresponding construction suggestions [21][22][23][24][25].…”