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Numerical Simulation of Variable Frequency Seepage Flow in Tunnel
Surrounding Rock Joint Fractures
(1. Zhuhai Institute of Urban Planning & Design, Zhuhai 519000; 2. Guangdong Coastal Area Disaster Prevention and Mitigation
Engineering Technology Research Center，Zhuhai 519000; 3. Zhuhai Da Heng Qin Company Limited, Zhuhai 519000;
4. China Railway 18th Bureau Group Co., Ltd, Tianjin 120000; 5. School of Civil Engineering, Sun Yat-Sen University,
Zhuhai 519082)
Abstract The seepage characteristics of rock joints and fractures are of significant importance for exploring the
mechanisms of geological disasters induced by tunnel excavation. This study employs COMSOL numerical simula?
tion software to investigate the cyclic water injection in rock joint fractures under varying amplitudes and frequencies. The results indicate that under cyclic water injection conditions, the flow pattern of the fluid within the fractures exhibits periodic changes with the inlet flow rate. Higher water injection amplitudes lead to more chaotic vortex patterns in low flow velocity regions. The permeability of the fractures also changes periodically with the inlet flow rate; specifically, when the injection flow rate decreases from its peak to its trough, the permeability increases from a trough value of 8.9×10?? m2 to 11.1×10?? m2. Moreover, the amplitude of permeability fluctuations increases with the rise in injection frequency and amplitude. Additionally, a simple and effective method for delineating flow regions is proposed, which allows for the identification and quantitative calculation of the main flow domain and vortex regions
in the fractures.
Abstract：
The seepage characteristics of rock joints and fractures are of significant importance for exploring the
mechanisms of geological disasters induced by tunnel excavation. This study employs COMSOL numerical simula?
tion software to investigate the cyclic water injection in rock joint fractures under varying amplitudes and frequencies. The results indicate that under cyclic water injection conditions, the flow pattern of the fluid within the fractures exhibits periodic changes with the inlet flow rate. Higher water injection amplitudes lead to more chaotic vortex patterns in low flow velocity regions. The permeability of the fractures also changes periodically with the inlet flow rate; specifically, when the injection flow rate decreases from its peak to its trough, the permeability increases from a trough value of 8.9×10?? m2 to 11.1×10?? m2. Moreover, the amplitude of permeability fluctuations increases with the rise in injection frequency and amplitude. Additionally, a simple and effective method for delineating flow regions is proposed, which allows for the identification and quantitative calculation of the main flow domain and vortex regions
in the fractures.
LI Dong1 ZHOU Yue2 WANG Feng3 LI Weipeng4 YE Jiexian5 CAO Xiong1 BAI Zhenchao5
.Numerical Simulation of Variable Frequency Seepage Flow in Tunnel
Surrounding Rock Joint Fractures[J] MODERN TUNNELLING TECHNOLOGY, 2024,V61(5): 146-155
2024, Vol. 61 