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| Analytical solution of head distribution on tunnel structure adjacent water-filled fault in water-enriched mountain region |
| ZHANG Zhiguo1，2，3，4，WANG Jiacheng1，ZHAO Qihua2，ZHANG Mengxi3，
WANG Zhiwei4 ，SUN Liangqian5，ZHANG Junru6 |
| (1. School of Environment and Architecture，University of Shanghai for Science and Technology，Shanghai 200093，China；2. State Key Laboratory of Geohazard Prevention and Geoenvironment Protection，Chengdu University of Technology，Chengdu，Sichuan 610059，China；3. Department of Civil Engineering，Shanghai University，Shanghai 200444，China；4. State Key
Laboratory for Track Technology of High-speed Railway，China Academy of Railway Sciences，Beijing 100081，China；
5. The 1th Engineering Co.，Ltd. of China Railway 12th Bureau Group，Xi?an，Shaanxi 710038，China；
6. School of Civil Engineering，Southwest Jiaotong University，Chengdu，Sichuan 610031，China) |
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Abstract Tunnels in mountainous areas are often in high head areas with multiple faults. Currently，very few studies paid attention to the seepage field of deep tunnels surrounded by rocks under the combined action of high far-field head and the head of water-filled fault. To investigate the influence of the size of head and the uneven distribution under the combined action，this paper provides a theoretical basis for the tunnel reinforcement design. Based on the mirror image method and seepage theory，the tunnel drainage volume and the change law of the head at the key locations area are obtained，such as the lining，grouting circle and surrounding rock of the deep circular tunnel buried in the water-enriched area. Meanwhile，the head difference parameter is introduced to solve the uneven distribution law of the water head. The finite element numerical simulation is used to numerically simulate the geological conditions of this problem. The numerical simulation results are then checked with the results of the theoretical analysis，and good consistency is obtained. Moreover，this paper performs a sensitivity analysis on the influence of the parameters on the seepage field and the distribution law of the head such as the size of the water-filled fault head，the distance between the fault and the tunnel，the dip angle of the fault and the tunnel drainage volume after drainage ditch is set. The main findings are as follows：(1) the water head on the tunnel structure increases as the water-filled fault head enlarges，while the uneven distribution decreases；(2) the head and the uneven distribution on the tunnel structure decrease as the distance between the fault and the center of the tunnel increases；(3) the fault dip mainly affects the uneven distribution of the water head on the tunnel structure. The connection line between the point at the maximum and the point at the minimum of the water head on the tunnel structure at the same circumference from the center of the tunnel is always perpendicular to the fault. The research results can provide a theoretical basis for tunnel excavation and operation in the water-enriched mountain areas and the unfavorable geological environments with faults.
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2020, Vol. 39 
