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The transportation and disposal of tunnel muck have detrimental environmental impacts. For this reason, the practice of reusing such a resource in engineering materials has substantial environmental and economic benefits. Seasonal frozen regions are extensively distributed worldwide, and freeze–thaw (F-T) cycles can largely degrade the performance of engineering materials, underscoring the importance of knowledge on the F-T resistance of tunnel muck. This study investigates the impact of F-T cycles on the mechanical and microscopic behavior of slurry shield tunnel muck stabilized with basalt fiber (BF) and inorganic curing agent (ICA). The qualities of muck discharged from slurry shield tunneling were improved in the composite formation of fine sand and muddy silty clay. Then tests were conducted to obtain the stress-strain characteristics, uniaxial compressive strength (UCS), and microstructure of the improved tunnel muck with different numbers of F-T cycles (N) and BF contents. Based on the Weibull probability distribution function, the damage evolution model of ICA-BF stabilized tunnel muck was proposed. The results show that the UCS decreases parabolically when the F-T cycle increases, and the F-T damage degree is 24.5%–40.6% after 12 cycles. Increasing BF content can effectively improve tunnel muck's F-T resistance (an optimal ratio of 0.5%). The failure strain of the reinforced tunnel muck is linearly correlated to the BF content and has a weak correlation with the number of F-T cycles. The F-T damage to material strength can be divided into rapid (N=0–3), slow (N=3–9), and stable (N>9) stages. The established F-T damage model can accurately predict the evolution of the F-T damage degree. [ABSTRACT FROM AUTHOR]

To explore the floating patterns of large-diameter shield tail segments in high water pressure silty clay strata and its correlation with construction parameters, an indoor grout mixing proportion and property test and a field test in Yellow river-crossing tunnel in Jinan, China are conducted. The results reveal the following: (1) Increasing the dosage of cement, fly ash, and water-reducing agent shortens the setting time of the grout, which is conducive to the decrease of segment floating. A decrease in the bleeding rate, fluidity, and consistency is unfavorable to segment floating control. (2) The floating of large-diameter shield tail segments presents a parabolic. It quickly rises within 10 hours after synchronous grouting, then slows down rapidly, and becomes stable after 25 -30 h. (3) The floating of segments are affected by various factors, it is recommended to dynamically adjust the grout mixing proportions, control the difference between of slurry discharged and entering volumes, reduce the cutterhead contact pressure, maintain the cutterhead torque, reduce the difference of thrust pressure between upper and lower section jack and synchronous grouting pressure difference, as well as appropriately extend the temporary downtime, driving and assembling time of the segment, and reduce tunneling speed. [ABSTRACT FROM AUTHOR]