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Analysis of Rapid Scaling Causes in Tunnel Drainage System and Relevant Inhibition Technologies
(1. Guangdong Road and Bridge Construction Development Co., Ltd., Guangzhou 510655; 2. Jiangsu Research Institute of Building Science Co. Ltd., State Key Laboratory of High Performance Civil Engineering Materials, Nanjing 210008;3. Jiangsu Sobute New Materials Co. Ltd., Nanjing 211103)
Abstract Rapid scaling and blockage of the tunnel drainage system will increase the water pressure behind the support, leading to secondary defects such as water seepage, deformation and collapse of lining. In this study, a tunnel in Guangdong province is used as a study case, which experienced severe leakage and crystallization of initial support, and scaling blockage in the drainage system during construction. The causes of rapid scaling of calcium carbonate in the drainage pipe are studied by analyzing the flow direction of surrounding rock water, spatio-temporal changes in ion concentration in water quality analysis, and the composition of scaling minerals. It is clarified that the initial support concrete plays a key role in scaling blockage in the drainage system. Further research is conducted on the effects of alkali accelerator, alkali-free accelerator, and densifying hydrophobic material on corrosion resistance of initial support concrete. The results show that the precipitation of Ga2+ and OH- from the initial support con? crete raises the pH value of the surrounding rock water from approximately 7.5 to 10.5, accelerating the generation of calcium carbonate scaling products; Compared to the initial support concrete mixed with only alkali accelerator, the initial support concrete mixed with combined alkali-free accelerator and hydrophobic material shows a 35.3% increase in 28 d compressive strength, a 26.6% decrease in RCM, and a 68.1% decrease in water absorption. By utilizing the densifying and hydrophobic collaborative technology for the matrix, dissolution and precipitation of internal calcium hydroxide are significantly inhibited; The engineering application directly proves that the densifying and hydrophobic technology for initial support concrete matrix can effectively alleviate scaling and blockage in the drainage system.
Abstract：
Rapid scaling and blockage of the tunnel drainage system will increase the water pressure behind the support, leading to secondary defects such as water seepage, deformation and collapse of lining. In this study, a tunnel in Guangdong province is used as a study case, which experienced severe leakage and crystallization of initial support, and scaling blockage in the drainage system during construction. The causes of rapid scaling of calcium carbonate in the drainage pipe are studied by analyzing the flow direction of surrounding rock water, spatio-temporal changes in ion concentration in water quality analysis, and the composition of scaling minerals. It is clarified that the initial support concrete plays a key role in scaling blockage in the drainage system. Further research is conducted on the effects of alkali accelerator, alkali-free accelerator, and densifying hydrophobic material on corrosion resistance of initial support concrete. The results show that the precipitation of Ga2+ and OH- from the initial support con? crete raises the pH value of the surrounding rock water from approximately 7.5 to 10.5, accelerating the generation of calcium carbonate scaling products; Compared to the initial support concrete mixed with only alkali accelerator, the initial support concrete mixed with combined alkali-free accelerator and hydrophobic material shows a 35.3% increase in 28 d compressive strength, a 26.6% decrease in RCM, and a 68.1% decrease in water absorption. By utilizing the densifying and hydrophobic collaborative technology for the matrix, dissolution and precipitation of internal calcium hydroxide are significantly inhibited; The engineering application directly proves that the densifying and hydrophobic technology for initial support concrete matrix can effectively alleviate scaling and blockage in the drainage system.
PU Chunping1 LU Jiayue2,
3 MU Song2,
3 XIE Deqing2 etc
.Analysis of Rapid Scaling Causes in Tunnel Drainage System and Relevant Inhibition Technologies[J] MODERN TUNNELLING TECHNOLOGY, 2023,V60(5): 254-261
2023, Vol. 60 