In perennially frozen or seasonally frozen soil regions,freeze-thaw cycling adversely impacts the mechanical properties of rock mass,resulting in landslides,rock erosion,and other geological disasters.The microscopic ...In perennially frozen or seasonally frozen soil regions,freeze-thaw cycling adversely impacts the mechanical properties of rock mass,resulting in landslides,rock erosion,and other geological disasters.The microscopic damage evolution law of loaded sandstone under the freeze-thaw cycle is analyzed by conducting Nuclear Magnetic Resonance(NMR)and uniaxial compression acoustic emission(AE)experiments.The experimental results have shown that:(1)Freeze-thaw cycling increases sandstone's internal pores,enlarges the pore size,and modifies the original pore distribution.(2)The damage due to freeze-thaw cycling is positively correlated with the initial damage to the rock,and the damage on the rock surface is more severe than inside the rock sample.(3)Freeze-thaw cycling negatively impacts the mechanical properties of sandstone,and the elastic deformation stage of sandstone gradually decreases as the number of freeze-thaw cycles increases and gradually transitions from brittle failure to ductile failure.(4)The characteristic parameters of AE ringing count and accumulated energy can reveal the severity of freeze-thaw damage and the dynamic evolution process,and the damage development rate exhibits abrupt changes at critical moments.After five freeze-thaw cycles,the damage development rate rises suddenly,as manifested by a sharp increase in the frequency and energy of AE events.High-energy AE events frequently occur during the rapid expansion period of damage,which can be adopted as an essential reference for damage propagation and aggravation.展开更多
基金supported by the National Natural Science Foundation of China(42277172,42177144,42077274,51774231,41702339)Funded by the Natural Science Basic Research Program of Shaanxi Province(2020JZ-53).
文摘In perennially frozen or seasonally frozen soil regions,freeze-thaw cycling adversely impacts the mechanical properties of rock mass,resulting in landslides,rock erosion,and other geological disasters.The microscopic damage evolution law of loaded sandstone under the freeze-thaw cycle is analyzed by conducting Nuclear Magnetic Resonance(NMR)and uniaxial compression acoustic emission(AE)experiments.The experimental results have shown that:(1)Freeze-thaw cycling increases sandstone's internal pores,enlarges the pore size,and modifies the original pore distribution.(2)The damage due to freeze-thaw cycling is positively correlated with the initial damage to the rock,and the damage on the rock surface is more severe than inside the rock sample.(3)Freeze-thaw cycling negatively impacts the mechanical properties of sandstone,and the elastic deformation stage of sandstone gradually decreases as the number of freeze-thaw cycles increases and gradually transitions from brittle failure to ductile failure.(4)The characteristic parameters of AE ringing count and accumulated energy can reveal the severity of freeze-thaw damage and the dynamic evolution process,and the damage development rate exhibits abrupt changes at critical moments.After five freeze-thaw cycles,the damage development rate rises suddenly,as manifested by a sharp increase in the frequency and energy of AE events.High-energy AE events frequently occur during the rapid expansion period of damage,which can be adopted as an essential reference for damage propagation and aggravation.
