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Study on Grouting Technology for Water Gushing in Sandy Dolomite Stratum with High Water Level
(1. China Railway ERJU 1st Engineering Co., Ltd., Guiyang 550007; 2. China Railway Development and Investment Group Co., Ltd.,Kunming 650200; 3. Key Laboratory of Traffic Tunnel Engineering, Ministry of Education, Southwest Jiaotong University,Chengdu 610031)
Abstract Sandy dolomite is characterized by developed joints and fractures. When the groundwater level is above the tunnel crown and the fractures and joints are densely developed, abundant groundwater can change its flow direction under the influence of hydraulic head, accumulating towards the tunnel excavation face and causing water gushing. To reduce construction risks and address the issue of unsatisfied grouting reinforcement quality, the study,based on the Central Yunnan Water Diversion Project, employs field analysis, numerical simulation, and engineering practice methods to investigate grouting parameters such as grouting pressure, grout mix ratio, and grouting thickness suitable for moderately sandy dolomite, as well as the corresponding construction techniques. The results indicate that in sandy dolomite stratum the grouting length should be controlled within 20 m, the reinforcement range outside the excavation profile should be around 4 m, the final grouting pressure should be controlled within 12 MPa,the grout diffusion radius should be within 1.5 m, and the mix ratio of single-component grout and double-component grout should be 1∶1. As for the grouting process, it should use long and short pipe combined grouting technology to avoid grout backflow, increase grouting pressure, extend the length of grouting sections, accelerate construction progress, and improve grouting reinforcement quality.
Abstract：
Sandy dolomite is characterized by developed joints and fractures. When the groundwater level is above the tunnel crown and the fractures and joints are densely developed, abundant groundwater can change its flow direction under the influence of hydraulic head, accumulating towards the tunnel excavation face and causing water gushing. To reduce construction risks and address the issue of unsatisfied grouting reinforcement quality, the study,based on the Central Yunnan Water Diversion Project, employs field analysis, numerical simulation, and engineering practice methods to investigate grouting parameters such as grouting pressure, grout mix ratio, and grouting thickness suitable for moderately sandy dolomite, as well as the corresponding construction techniques. The results indicate that in sandy dolomite stratum the grouting length should be controlled within 20 m, the reinforcement range outside the excavation profile should be around 4 m, the final grouting pressure should be controlled within 12 MPa,the grout diffusion radius should be within 1.5 m, and the mix ratio of single-component grout and double-component grout should be 1∶1. As for the grouting process, it should use long and short pipe combined grouting technology to avoid grout backflow, increase grouting pressure, extend the length of grouting sections, accelerate construction progress, and improve grouting reinforcement quality.
YANG Fan1 HE Fusheng1 YAN Qixiang3 LI Weidong2 CHEN Jian2 ZHAO Zechang3
.Study on Grouting Technology for Water Gushing in Sandy Dolomite Stratum with High Water Level[J] MODERN TUNNELLING TECHNOLOGY, 2024,V61(4): 255-265
2024, Vol. 61 