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  2024, Vol. 43 Issue (11): 2655-2668    DOI: 10.13722/j.cnki.jrme.2024.0156
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Study on the deformation characteristics of sandstone under dynamic pre-peak unloading and wetting-swelling cycles
ZHAO Erping,ZHANG Cong,LI Jianlin,LI Zhikun,DENG Huafeng
(Hubei Key Laboratory of Disaster Prevention and Mitigation,China Three Gorges University,Yichang,Hubei 443002,China)
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Abstract  The continuous excavation of engineering projects leads to dynamic unloading and damage effects on the surrounding rock,and the mechanical and hydraulic properties of the unloaded and damaged rock mass jointly affect the stability and safety of the project. In view of this,this paper analyzes the deformation characteristics of medium-to-fine-grained quartz sandstone under dynamic pre-peak unloading and wetting-swelling cycles from both macro and micro perspectives. The results indicate that the peak strength of the unloaded and damaged samples is significantly reduced,and the degree of sample failure intensifies. Under the cyclic action of dynamic unloading and wetting-swelling cycles,the cumulative damage of the samples generally shows an upward trend. The more cyclic action of unloading and wetting-swelling,the greater the increment in porosity and the more water absorbed due to swelling. The micro-damage index exhibits an exponential growth pattern with the cycle number. As the destruction approaches,the proportion of medium- and large-sized pores in the samples increases. The greater the unloading amount,the less action required for the destruction of the sample,with an unloading amount of 50% defined as the threshold for controlling the destruction rate under unloading and wetting-swelling cycles. When the unloading amount exceeds 50%,the destruction process accelerates. By incorporating unloading damage and wetting-drying cycle times into the Hooke element to modify the Kelvin model,the swelling creep characteristics of the samples under dynamic excavation unloading conditions can be better simulated.
Key wordsrock mechanics      dynamic unloading      unloading damage      wetting-swelling      cyclic action      swelling creep constitutive model     
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ZHAO Erping
ZHANG Cong
LI Jianlin
LI Zhikun
DENG Huafeng
Cite this article:   
ZHAO Erping,ZHANG Cong,LI Jianlin, et al. Study on the deformation characteristics of sandstone under dynamic pre-peak unloading and wetting-swelling cycles[J]. , 2024, 43(11): 2655-2668.
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https://rockmech.whrsm.ac.cn/EN/10.13722/j.cnki.jrme.2024.0156      OR      https://rockmech.whrsm.ac.cn/EN/Y2024/V43/I11/2655
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