Abstract
Slurry shield construction generates substantial waste muck, which not only occupies site space but also causes environmental pollution and incurs additional disposal costs. To achieve resource utilization of muck and reduce construction costs, this study investigates the use of muck as a bentonite substitute in preparing synchronous grouting two-component slurry. Through microstructural analysis and performance testing, the viability of replacing bentonite with slurry shield muck from silty clay strata in two-component slurry preparation and the influencing characteristics of relevant factors were examined. The findings reveal that the clay content in this muck and the bentonite slurry injected into the cutterhead during tunneling can fulfill the role of bentonite in the original slurry. Furthermore, the influence patterns of muck content and sodium silicate Baumé degree on two-component slurry performance were elucidated; both muck content and sodium silicate Baumé degree exert significant effects on the bleeding rate, fluidity, initial setting time, and compressive strength of the two-component slurry. Muck content and fly ash-cement ratio demonstrate a significant interaction effect on slurry fluidity, while muck content and sodium silicate Baumé degree show a significant interaction effect on initial setting time. A practical two-component slurry mix proportion suitable for silty clay strata is proposed: Component A (cement 116.69 kg/m³, fly ash 378.28 kg/m³, muck 116.69 kg/m³, sand 798.32 kg/m³, water 409.06 kg/m³, silica fume 20.95 kg/m³, water reducer 2.99 kg/m³), Component B (28°Bé sodium silicate), with a volume ratio of Component A to Component B of 25:1. Application of this mix proportion in silty clay strata can reduce muck pollution and disposal costs, providing a reference for similar projects.
Full Text
Experimental Study on Mix Proportion of Two-Component Grout Based on Slurry Shield Tunneling Waste in Silty Clay Strata
Li Mingyu*,¹, Xiao Mingzhe¹, Chen Jian²,³, Gao Shijun²,³, Wang Hexiang¹, Li Huiqiang¹
¹ School of Civil Engineering, Zhengzhou University, Zhengzhou 450001, China
² China Railway 14th Bureau Group Co., Ltd., Jinan 250101, Shandong, China
³ China Railway 14th Bureau Group Shield Engineering Co., Ltd., Nanjing 211800, China
Abstract: Slurry shield tunneling generates substantial quantities of waste soil that not only occupies valuable site space but also causes environmental pollution and incurs significant disposal costs. To achieve resource utilization of this waste material and reduce construction expenses, this study investigates the feasibility of using excavated soil as a replacement for bentonite in synchronous grouting two-component grout systems. Through microscopic analysis and comprehensive performance testing, the viability of substituting bentonite with slurry shield tunneling waste from silty clay strata was evaluated, revealing that the inherent clay content in this waste, combined with the bentonite slurry injected to the cutterhead during excavation, can effectively fulfill the functions of conventional bentonite in grout mixtures. The research also elucidates the influence patterns of waste soil content and sodium silicate Baume degree on critical grout properties, demonstrating significant effects on bleeding rate, fluidity, initial setting time, and compressive strength. Statistical analysis reveals significant interaction effects between waste soil content and fly ash-cement ratio on grout fluidity, as well as between waste soil content and sodium silicate Baume degree on initial setting time. Based on these findings, a practical two-component grout mix proportion suitable for silty clay strata is recommended: Liquid A (cement 116.69 kg/m³, fly ash 378.28 kg/m³, waste soil 116.69 kg/m³, sand 798.32 kg/m³, water 409.06 kg/m³, silica fume 20.95 kg/m³, water reducer 2.99 kg/m³) and Liquid B (28°Bé sodium silicate), with an A:B volume ratio of 25:1. This optimized mix proportion can substantially reduce waste soil pollution and disposal costs when applied in silty clay strata, offering a valuable reference for similar tunneling projects.
Keywords: slurry shield; waste soil reuse; two-component grout; response surface; mix proportion optimization