Abstract Modifying the muck discharged from a shield tunnel into subgrade material will significantly increase the utilization efficiency of resources, but the freeze-thaw conditions will create safety hazard. By using a shield tunnel of Heping Avenue in Wuhan as the example and using the spoil from large-diameter slurry shield as the study object, the shield spoil is modified by adding the independently developed waste solid based gelatinizer (Cement-SlagGypsum-Alum, CSGA) and basalt fiber (BF), and the shield spoil modified by CSGA-BF is subjected to freezethaw cycle test, in order to investigate how the parameters such as amount of basalt fiber and number of freeze-thaw cycles will affect the appearance deterioration characteristics, mechanical properties and microscopic damage mechanism of improved shield spoil. As the results indicate: Under the effect of freeze-thaw cycle, the volume of modified spoil changes in a wave-like pattern, and it generally exhibits volume expansion. As the number of freeze-thaw cycles increases, both the unconfined compressive strength and modulus of elasticity of the modified shield spoil decrease non-linearly. Adding a proper amount of basalt fiber will increase the friction at the reinforcement-soil interface,which is important to frost resistance of spoil. However, excessive amount of fiber will degrade the strength of the specimen. When the number of freeze-thaw cycles is 9, the compressive strength and modulus of elasticity of the modified shield spoil stabilize, and the pores become interconnected.
Abstract：
Modifying the muck discharged from a shield tunnel into subgrade material will significantly increase the utilization efficiency of resources, but the freeze-thaw conditions will create safety hazard. By using a shield tunnel of Heping Avenue in Wuhan as the example and using the spoil from large-diameter slurry shield as the study object, the shield spoil is modified by adding the independently developed waste solid based gelatinizer (Cement-SlagGypsum-Alum, CSGA) and basalt fiber (BF), and the shield spoil modified by CSGA-BF is subjected to freezethaw cycle test, in order to investigate how the parameters such as amount of basalt fiber and number of freeze-thaw cycles will affect the appearance deterioration characteristics, mechanical properties and microscopic damage mechanism of improved shield spoil. As the results indicate: Under the effect of freeze-thaw cycle, the volume of modified spoil changes in a wave-like pattern, and it generally exhibits volume expansion. As the number of freeze-thaw cycles increases, both the unconfined compressive strength and modulus of elasticity of the modified shield spoil decrease non-linearly. Adding a proper amount of basalt fiber will increase the friction at the reinforcement-soil interface,which is important to frost resistance of spoil. However, excessive amount of fiber will degrade the strength of the specimen. When the number of freeze-thaw cycles is 9, the compressive strength and modulus of elasticity of the modified shield spoil stabilize, and the pores become interconnected.
ZHANG Jianyong
.Study on Deterioration Characteristics of Modified Slurry Shield Spoil Based on Freeze-thaw Cycle Test[J] MODERN TUNNELLING TECHNOLOGY, 2024,V61(1): 260-271
2024, Vol. 61 