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Influence of Weathered Mudstone Powders on the Properties of Slurry and Filter Cake in Slurry Shield Tunnelling
(1. CCCC Tunnel Engineering Company Limited, Beijing 100102; 2. Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing 210098; 3. School of Civil Engineering and Transportation, Hohai University,Nanjing 210098)
Abstract To address the issue of a large amount of mudstone powders mixing into the slurry during slurry shield tunnelling in weathered rock layers, this study uses weathered mudstone powders to replace bentonite in different proportions and simulates the process of changes in the properties of slurry. The parameters including slurry viscosity,bleeding rate, Zeta potential, particle gradation, and filtration loss during the filter cake formation process are tested to explore the effect of the mudstone powder mix ratio on slurry and filter cake properties, and the mechanisms of the changes in properties are analyzed. The results show that the addition of mudstone powders significantly reduces slurry viscosity, increases the bleeding rate, causes particle agglomeration in the slurry, and lowers the Zeta potential.When the mix proportion of mudstone powders is 30%, the filter cake becomes denser, and compared with pure bentonite slurry, the permeability coefficient decreases by 70.30%, and the porosity decreases by 43.94%. Under a pressure of 0.45 MPa, the air-tight time exceeds 320 minutes. However, when the mudstone powder mix proportion exceeds 30%, the properties of the filter cake decline significantly. The reduction of Zeta potential in slurry when mud? stone powder is added is a key factor in the increase in particle size, the increase in bleeding rate, and the decrease in air-tight time and air-tight value in the filter cake.
Abstract：
To address the issue of a large amount of mudstone powders mixing into the slurry during slurry shield tunnelling in weathered rock layers, this study uses weathered mudstone powders to replace bentonite in different proportions and simulates the process of changes in the properties of slurry. The parameters including slurry viscosity,bleeding rate, Zeta potential, particle gradation, and filtration loss during the filter cake formation process are tested to explore the effect of the mudstone powder mix ratio on slurry and filter cake properties, and the mechanisms of the changes in properties are analyzed. The results show that the addition of mudstone powders significantly reduces slurry viscosity, increases the bleeding rate, causes particle agglomeration in the slurry, and lowers the Zeta potential.When the mix proportion of mudstone powders is 30%, the filter cake becomes denser, and compared with pure bentonite slurry, the permeability coefficient decreases by 70.30%, and the porosity decreases by 43.94%. Under a pressure of 0.45 MPa, the air-tight time exceeds 320 minutes. However, when the mudstone powder mix proportion exceeds 30%, the properties of the filter cake decline significantly. The reduction of Zeta potential in slurry when mud? stone powder is added is a key factor in the increase in particle size, the increase in bleeding rate, and the decrease in air-tight time and air-tight value in the filter cake.
LIU Tao1 ZHANG Lei YIN Wenjun2,
3 SHI Zhipeng1 QIAN Yongjin2,
3 WANG Shiyu2 etc
.Influence of Weathered Mudstone Powders on the Properties of Slurry and Filter Cake in Slurry Shield Tunnelling[J] MODERN TUNNELLING TECHNOLOGY, 2025,V62(3): 182-189
2025, Vol. 62 