动态峰前卸荷-湿胀循环作用下砂岩变形特性研究  

Study on the deformation characteristics of sandstone under dynamic pre-peak unloading and wetting-swelling cycles

作　　者：赵二平[1] 张聪 李建林[1] 李志坤[1] 邓华锋[1] 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)

机构地区：[1]三峡大学防灾减灾湖北省重点实验室,湖北宜昌443002

出　　处：《岩石力学与工程学报》2024年第11期2655-2668,共14页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(U2034203)。

摘　　要：工程连续开挖施工导致围岩产生动态卸荷损伤效应,而卸荷损伤岩体的力学性能以及水理性质又共同影响工程的稳定和安全。鉴于此,从宏细观多角度分析动态峰前卸荷-湿胀循环作用下中-细粒岩屑石英砂岩的变形特征。结果表明,卸荷损伤试样峰值强度显著降低,试样破坏程度加剧;动态卸荷-湿胀循环作用下试样累积损伤度整体呈上升趋势;卸荷-湿胀循环作用次数越多,孔隙度增量越大,膨胀吸水量越多;细观损伤程度随循环次数呈指数形式逐渐增加;临破坏时,试样中,大尺寸孔隙占比均增加;卸荷量越大,试样破坏时的作用次数越少,界定卸荷量50%为卸荷-湿胀循环作用破坏速度控制阈值,当卸荷量大于50%时,破坏进程较快;将卸荷损伤及干湿循环次数引入Hooke元件修正Kelvin模型,可以较好地模拟动态开挖卸荷条件下试样的膨胀蠕变特性。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.

关 键 词：岩石力学 动态卸荷 卸荷损伤 湿胀 循环作用 膨胀蠕变本构模型 

分 类 号：TU45[建筑科学—岩土工程]