Research on the Stability of Shallow-Buried Large Cross-Section Tunnel by Construction Method Conversion

Abstract

The blind and random use of the combined construction method may have a great impact on tunnel stability. To determine the influence of construction method conversion on tunnel deformation and the reasonable conversion condition, a numerical model is established to simulate the construction method transforms from central diaphragm method to the benching tunneling method based on Jiaoweiqin Tunnel. The conversion condition is determined based on the results of tunnel geological prediction and in-site monitoring, and the temporary two-bench tunneling method is adopted to ensure the success of construction method conversion. Besides, the parameter analysis is done to analyze the influence of mechanical properties of surrounding rock mass and bench length on tunnel stability. Research results indicate that the construction safety should be evaluated before construction method conversion is carried out by analyzing the design blueprint, tunnel geological prediction results, geological survey reports, rock mass conditions in front of tunnel face, in-site monitoring data, and numerical simulation results. Meanwhile, the construction method conversion can be carried out in the order of central diaphragm method, two-bench tunneling method, and bench tunneling method. Parameter analysis results reveal that the deformation of primary support decreases in a negative exponential form with the increase in elasticity modulus and increases approximately linearly with the increase in bench length. For shallow buried and large cross-section tunnels, the tunnel deformation is in a small state when the elastic modulus of rock mass reaches a certain value. The construction method conversion can be carried out when the rock mass has a certain stability, and the length of construction method conversion should be small to ensure construction safety.

A design analysis method and its application in the cover arch of cut-and-cover tunnels

“…Zhu characterized the deformation of the rock in front of a tunnel under different ground stress soft rock conditions through model tests (Zhu et al, 2022). Zhang studied the construction method of large sections of shallowly buried tunnels and determined the method of construction conversion (Zhang et al, 2022). The cut and cover method includes two structural forms: one is a rectangular cross section, mainly used for the construction of urban subway stations; the other is a five-centered circle cross section, mainly used for mountainous tunnels (Kazuhito et al, 1999;Xiao et al, 2018).…”

Study of the disaster-causing mechanism and reinforcement measures for soft rock deformation and lining cracking

“…The construction methods are of great significance to surrounding rock stability and construction safety. In particular, timely and reasonable supporting structures should be constructed after tunneling in the soft stratum to avoid surrounding rock deformation and structural damage (Mikaeil et al, 2019;Li et al, 2020;Leng et al, 2021;Li et al, 2021;Pandit and Babu 2021;Liu et al, 2022a;Zhang et al, 2022c;Zhang et al, 2022d;Guan et al, 2022). Rooh et al (2018) established a comprehensive simulation program to study the relationship between rock mass quality and longitudinal displacement profile (LDP).…”

Numerical simulation of ground surface settlement of underpass building in tunnel boring machine double-line tunnels

“…The upper part is assumed at the ground level, while the lower part is set to 26.4 m, which is four times the excavating diameter. Accordingly, the dimensions of the three-dimensional computing model are 120 m × 135 m × 58 m. The boundary conditions are horizontal constraint around the model, vertical constraint into the bottom, and the ground surface being free (Zhang et al, 2022). Figure 5 shows the established model and the imposed boundary conditions.…”