Abstract In the excavation process of tunnels with high geostress, the original stress equilibrium state is destroyed causing the stress concentration phenomenon and occurrence of serious geologic hazards such as rockburst, wall caving and so on. Based on the Tingzhou tunnel on Ganzhou-Longyan railway in Fujian province, it uses 3D-Sigma software to establish a 3D three-dimensional tunnel excavation numerical model. Taking the stress data obtained by hydraulic fracturing as boundary conditions and estimating the input parameters of the rock mass on the basis of Hoek-Brown strength criterion, the distribution and variation of stress field in the process of tunnel excavation is explored. The results show that in the process of tunnel excavation, the maximum horizontal principal stress, shear stress will form stress concentration area at the top of the arch and arch shoulder, which will lead to brittle failure of rocks. Through simulation monitoring of 7 typical positions on the same cross section of the tunnel, it is found that the changes of the stress field at the top of the arch, the arch shoulder and the bottom of the tunnel are obviously sensitive to the excavation of the tunnel, the rockburst will be more easily occur at these positions. The predicted rockburst locations by the numerical simulation tally with the practical rockburst occurrence locations in the project case. Therefore, the numerical simulation results can be used to explain the regularity of the rockburst, providing some guiding values for the prevention of the engineering rockburst.
Abstract：
In the excavation process of tunnels with high geostress, the original stress equilibrium state is destroyed causing the stress concentration phenomenon and occurrence of serious geologic hazards such as rockburst, wall caving and so on. Based on the Tingzhou tunnel on Ganzhou-Longyan railway in Fujian province, it uses 3D-Sigma software to establish a 3D three-dimensional tunnel excavation numerical model. Taking the stress data obtained by hydraulic fracturing as boundary conditions and estimating the input parameters of the rock mass on the basis of Hoek-Brown strength criterion, the distribution and variation of stress field in the process of tunnel excavation is explored. The results show that in the process of tunnel excavation, the maximum horizontal principal stress, shear stress will form stress concentration area at the top of the arch and arch shoulder, which will lead to brittle failure of rocks. Through simulation monitoring of 7 typical positions on the same cross section of the tunnel, it is found that the changes of the stress field at the top of the arch, the arch shoulder and the bottom of the tunnel are obviously sensitive to the excavation of the tunnel, the rockburst will be more easily occur at these positions. The predicted rockburst locations by the numerical simulation tally with the practical rockburst occurrence locations in the project case. Therefore, the numerical simulation results can be used to explain the regularity of the rockburst, providing some guiding values for the prevention of the engineering rockburst.
WEI Yinghua LIU Fei
.Numerical Simulation Analysis of the Rockburst Mechanism in the Tunnel with High Geostress[J] MODERN TUNNELLING TECHNOLOGY, 2020,V57(6): 46-54
2020, Vol. 57 