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| Analysis of initial ground stress field and prediction of rockurst in Ganqing Tunnel |
| LI Qidi1, LIANG Qingguo1*, ZHOU Ren2, YANG Jiawei2, CAI Zunle1
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1. School of Civil Engineering, Lanzhou Jiaotong University, Lanzhou 730070, Gansu, China;
2. China Railway No. 2 Engineering Group Co., Ltd., Chengdu 610031, Sichuan, China |
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Abstract In order to explore the distribution law of the initial ground stress field in the Ganqing Tunnel engineering area of Xicheng Railway and accurately predict the rockburst, the principle of multiple linear regression was adopted. Based on the measured stress data, landform, stratum & lithology, geologic structure and experimental research results, etc., the FLAC3D numerical simulation analysis software was used to invert and analyze the initial stress field of the project area. The research analyzed the stress redistribution and local stress concentration after unloading during tunnel excavation, and predicted the specific location and strength of rock burst that may occur in the high stress section of the tunnel based on the modified "Gu-Tao rockburst criterion". The research results indicated that the Ganqing Tunnel is located in a high stress environment with complex geological structures, high stress concentration, and large burial depth. The Yanshanian diorite and Triassic slate rock masses were hard and intact, and there is a risk of rockburst; The maximum principal stress in the Ganqing Tunnel project area was 2.3-25.2 MPa, and the minimum principal stress was 1.0-15.8 MPa. The relationship between the triaxial principal stress was SH>Sh>SV when the burial depth was less than 300 m, and SH>SV>Sh when the burial depth was 300-700 m. The stress characteristics were mainly horizontal structural stress; The Ganqing Tunnel as a whole presented a weak to moderate rockburst state. The Ganqing Tunnel DK394+700—DK398+500 had the conditions for high rockburst activity, while DK384+500—DK394+700 and DK398+500—402+200 had the conditions for moderate rockburst activity.
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Received: 23 June 2024
Published: 08 January 2025
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