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Experimental Study on the Property Change of CMC-Modified Seawater Slurry and Filter Cake Formation in Sand Strata
(1. Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering (Hohai University), Nanjing 210098;2. School of Civil Engineering and Transportation, Hohai University, Nanjing 210098; 3. CCCC Tunnel Engineering Co., Ltd.,Beijing 100088)
Abstract In order to investigate the impact of sodium carboxymethyl cellulose (CMC) on the properties of seawater slurry and filter cake forming effect when a slurry shield drives through sand strata in the seabed, this paper prepares seawater slurry with different CMC dosages to analyze variation of properties of the slurry, such as water bleeding rate, viscosity and Zeta potential etc., and conducts tests on the slurry infiltration and filter cake formation. The results show that the viscosity of the slurry after the addition of CMC gradually increases compared with that of the seawater slurry, the 2 h water bleeding rate decreases significantly, the bound water content in the formed filter cake gradually increases, and the permeability coefficient of the filter cake decreases to 4.03×10-8 cm/s. The content of fine particles less than 75 μm in the modified seawater slurry increases significantly, and after resting for 24 hours the upper part of the slurry shows turbidity while the lower part still has serious precipitation. When the CMC dosing reaches 0.16%, the 2 h bleeding rate of the modified seawater slurry is less than 10%, and the permeation flow rate of the formed filter cake is less than 0.01 m3/m2, which can ensure the short-term stability of the slurry and form a dense filter cake.
Abstract：
In order to investigate the impact of sodium carboxymethyl cellulose (CMC) on the properties of seawater slurry and filter cake forming effect when a slurry shield drives through sand strata in the seabed, this paper prepares seawater slurry with different CMC dosages to analyze variation of properties of the slurry, such as water bleeding rate, viscosity and Zeta potential etc., and conducts tests on the slurry infiltration and filter cake formation. The results show that the viscosity of the slurry after the addition of CMC gradually increases compared with that of the seawater slurry, the 2 h water bleeding rate decreases significantly, the bound water content in the formed filter cake gradually increases, and the permeability coefficient of the filter cake decreases to 4.03×10-8 cm/s. The content of fine particles less than 75 μm in the modified seawater slurry increases significantly, and after resting for 24 hours the upper part of the slurry shows turbidity while the lower part still has serious precipitation. When the CMC dosing reaches 0.16%, the 2 h bleeding rate of the modified seawater slurry is less than 10%, and the permeation flow rate of the formed filter cake is less than 0.01 m3/m2, which can ensure the short-term stability of the slurry and form a dense filter cake.
.Experimental Study on the Property Change of CMC-Modified Seawater Slurry and Filter Cake Formation in Sand Strata[J] MODERN TUNNELLING TECHNOLOGY, 2022,V59(1): 249-255
2022, Vol. 59 