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Sodium-based Bentonite Slurry Improvement to Sandy Cobble Soil During Shield Excavation
https://orcid.org/https://orcid.org/0009-0008-3300-1161
https://orcid.org/https://orcid.org/0000-0002-9157-0417
https://orcid.org/https://orcid.org/0000-0002-6419-1438
https://orcid.org/https://orcid.org/0009-0003-8695-308X
Sandy cobble soil has characteristics including a large internal friction angle, high permeability coefficient, and poor fluidity, which can result in serious tool wear, groundwater spilling, and transportation difficulties during shield construction. A subway in Luoyang is presented as an example case of shield construction. The optimal soil-water ratio of the bentonite slurry is 1:10 based on a sand and cobble stratum in the shield construction, and the optimal expansion duration is 18 h. Large-scale shear, slump degree, and permeability tests were conducted on a sodium-based bentonite slurry mixed with the sandy cobble soil. It was found that, with increasing slurry injection rate, the viscosity of the sandy cobble soil increased; the sand and stone separation phenomenon gradually vanished; the shear strength, internal friction angle, and permeability coefficient non-linearly decreased; and the slump degree non-linearly increased. The slurry injection rate necessary to meet the friction requirement of sandy cobble soil in the shield construction was 17%; the slurry injection rate necessary to meet the permeability requirement was 14%; and the slurry injection rate necessary to meet the fluidity requirement was 13% – 17%. The total thrust and cutter torque of the shield were found to be reduced by approximately 1/3, and the earth pressure balance maintained relatively well after the sandy cobble soil was mixed with the bentonite slurry, these points being remarkably significant to the high-speed advance of shield construction. This study is important with respect to solving issues concerning sandy cobble layers in subway shields.
Sodium-based Bentonite Slurry Improvement to Sandy Cobble Soil During Shield Excavation
https://orcid.org/https://orcid.org/0009-0008-3300-1161
https://orcid.org/https://orcid.org/0000-0002-9157-0417
https://orcid.org/https://orcid.org/0000-0002-6419-1438
https://orcid.org/https://orcid.org/0009-0003-8695-308X
Sandy cobble soil has characteristics including a large internal friction angle, high permeability coefficient, and poor fluidity, which can result in serious tool wear, groundwater spilling, and transportation difficulties during shield construction. A subway in Luoyang is presented as an example case of shield construction. The optimal soil-water ratio of the bentonite slurry is 1:10 based on a sand and cobble stratum in the shield construction, and the optimal expansion duration is 18 h. Large-scale shear, slump degree, and permeability tests were conducted on a sodium-based bentonite slurry mixed with the sandy cobble soil. It was found that, with increasing slurry injection rate, the viscosity of the sandy cobble soil increased; the sand and stone separation phenomenon gradually vanished; the shear strength, internal friction angle, and permeability coefficient non-linearly decreased; and the slump degree non-linearly increased. The slurry injection rate necessary to meet the friction requirement of sandy cobble soil in the shield construction was 17%; the slurry injection rate necessary to meet the permeability requirement was 14%; and the slurry injection rate necessary to meet the fluidity requirement was 13% – 17%. The total thrust and cutter torque of the shield were found to be reduced by approximately 1/3, and the earth pressure balance maintained relatively well after the sandy cobble soil was mixed with the bentonite slurry, these points being remarkably significant to the high-speed advance of shield construction. This study is important with respect to solving issues concerning sandy cobble layers in subway shields.
Sodium-based Bentonite Slurry Improvement to Sandy Cobble Soil During Shield Excavation
https://orcid.org/https://orcid.org/0009-0008-3300-1161
https://orcid.org/https://orcid.org/0000-0002-9157-0417
https://orcid.org/https://orcid.org/0000-0002-6419-1438
https://orcid.org/https://orcid.org/0009-0003-8695-308X
Sandy cobble soil has characteristics including a large internal friction angle, high permeability coefficient, and poor fluidity, which can result in serious tool wear, groundwater spilling, and transportation difficulties during shield construction. A subway in Luoyang is presented as an example case of shield construction. The optimal soil-water ratio of the bentonite slurry is 1:10 based on a sand and cobble stratum in the shield construction, and the optimal expansion duration is 18 h. Large-scale shear, slump degree, and permeability tests were conducted on a sodium-based bentonite slurry mixed with the sandy cobble soil. It was found that, with increasing slurry injection rate, the viscosity of the sandy cobble soil increased; the sand and stone separation phenomenon gradually vanished; the shear strength, internal friction angle, and permeability coefficient non-linearly decreased; and the slump degree non-linearly increased. The slurry injection rate necessary to meet the friction requirement of sandy cobble soil in the shield construction was 17%; the slurry injection rate necessary to meet the permeability requirement was 14%; and the slurry injection rate necessary to meet the fluidity requirement was 13% – 17%. The total thrust and cutter torque of the shield were found to be reduced by approximately 1/3, and the earth pressure balance maintained relatively well after the sandy cobble soil was mixed with the bentonite slurry, these points being remarkably significant to the high-speed advance of shield construction. This study is important with respect to solving issues concerning sandy cobble layers in subway shields.
Sodium-based Bentonite Slurry Improvement to Sandy Cobble Soil During Shield Excavation
KSCE J Civ Eng
Dong, Wenping (author) / Wang, Chuang (author) / Dong, Jinyu (author) / Shi, Shang (author)
KSCE Journal of Civil Engineering ; 28 ; 4879-4886
2024-11-01
8 pages
Article (Journal)
Electronic Resource
English
Sodium-based Bentonite Slurry Improvement to Sandy Cobble Soil During Shield Excavation
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