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Numerical Simulation of the Rockburst Mechanism in the Meihuashan Tunnel
(1 China Railway No.5 Engineering Group Co. Ltd, Guiyang 364000;
2 School of Engineering and Technology, China University of Geosciences, Beijing 100083;
3 The First Monitoring Center Institute of Crustal Dynamics, The Institute of Crustal Dynamics, Tianjin 300180)
Abstract Affected by staged excavation, stress-strain nonlinear variation may occur inside the surrounding rock of a tunnel. In high-ground-stress areas, this mechanical effect tends to be even more obvious and can cause serious geological disasters like rockbursts and wall caving, etc. Taking the construction of the Meihuashan tunnel in Fujian as an example, this paper analyzes the interaction of the excavation steps and the change rule of the 3D stress field and strain field in the tunnel by establishing a 3D excavation numerical model with 3D-Sigmasoftware, using the measured stress data as a boundary condition and determining the inputs of the rock mass with the Hoek-Brown strength criterion. The results show that: because of high ground stress, compressive stress concentration occurs at the tunnel crown and shear stress concentration occurs at the spandrel, which may cause brittle failure at the tunnel wall; previously excavated tunnel sections may be affected by subsequent excavation, making the stress concentration effect more obvious and the failure of the surrounding rock more serious; the actual rockburst locations correspond with the locations of maximum compressive stress concentration and maximum shear stress concentration in simulation analysis. The numerical simulation can clearly reveal the mechanism and the possible law of the rock burst, providing strong technical support for engineering applications.
Abstract：
Affected by staged excavation, stress-strain nonlinear variation may occur inside the surrounding rock of a tunnel. In high-ground-stress areas, this mechanical effect tends to be even more obvious and can cause serious geological disasters like rockbursts and wall caving, etc. Taking the construction of the Meihuashan tunnel in Fujian as an example, this paper analyzes the interaction of the excavation steps and the change rule of the 3D stress field and strain field in the tunnel by establishing a 3D excavation numerical model with 3D-Sigmasoftware, using the measured stress data as a boundary condition and determining the inputs of the rock mass with the Hoek-Brown strength criterion. The results show that: because of high ground stress, compressive stress concentration occurs at the tunnel crown and shear stress concentration occurs at the spandrel, which may cause brittle failure at the tunnel wall; previously excavated tunnel sections may be affected by subsequent excavation, making the stress concentration effect more obvious and the failure of the surrounding rock more serious; the actual rockburst locations correspond with the locations of maximum compressive stress concentration and maximum shear stress concentration in simulation analysis. The numerical simulation can clearly reveal the mechanism and the possible law of the rock burst, providing strong technical support for engineering applications.
ZHANG Yi-Yu-1,
Xing-Bo-Rui-2,
Song-Cheng-Ke-3
.Numerical Simulation of the Rockburst Mechanism in the Meihuashan Tunnel[J] MODERN TUNNELLING TECHNOLOGY, 2014,V51(1): 97-104
2014, Vol. 51 