Abstract: The large amount of muck generated during earth pressure balance shield tunneling often causes environmental pollution and resource waste due to improper disposal. Meanwhile, bentonite, as a key conditioning agent, is an expensive nonrenewable resource. To improve the resource utilization of cohesive shield muck, this study proposes a green approach in which waste cohesive shield muck is used to partially replace bentonite for the preparation of soil conditioners. Bentonite content, cohesive shield muck content, and the sodium carbonate ratio are selected as the three influencing factors, while funnel viscosity, density, pH, and fluid loss are selected as response values. Experiments are designed based on the response surface methodology, and predictive models are established to describe the relationship between material proportions and conditioner performance. A self-developed pressurized permeameter is used to overcome the size effect of conventional tests, and the permeability improvement provided by the muck-based conditioner is systematically validated for three typical coarse-grained soils: cobble, gravelly sand, and medium coarse sand. The results show that: 1)the regression models established via the response surface methodology agree well with the experimental data and can effectively predict the performance of muck-based conditioners under different material proportions. 2)By introducing clay particles, the muck-based conditioner optimizes soil particle gradation. When the slurry injection rate exceeds 25%, the stabilized permeability coefficients of all three coarse-grained soil samples are reduced below the engineering safety threshold of 10^－5 m/s.

Key words: earth pressure balance shield, soil conditioning, permeability characteristics, response surface methodology, resource utilization