周期性孔隙水压作用下砂岩损伤劣化特性研究  

Damage and deterioration characteristics of sandstone under cyclical pore water pressure

作　　者：李洪亚 马林建 刘杰[2] 李增 邓家军 许宏发 LI Hong-ya;MA Lin-jian;LIU Jie;LI Zeng;DENG Jia-jun;XU Hong-fa(State Key Laboratory of Disaster Prevention and Mitigation of Explosion and Impact,Army Engineering University of PLA,Nanjing,Jiangsu 210007,China;Key Laboratory of Geological Hazards on Three Gorges Reservoir Area,Ministry of Education,China Three Gorges University,Yichang,Hubei 443002,China)

机构地区：[1]陆军工程大学爆炸冲击防灾减灾全国重点实验室,江苏南京210007 [2]三峡大学三峡库区地质灾害教育部重点实验室,湖北宜昌443002

出　　处：《岩土力学》2024年第7期2000-2010,共11页Rock and Soil Mechanics

基　　金：国家自然科学基金优秀青年基金(No.52222110);江苏省自然科学面上基金(No.BK20211230)。

摘　　要：消落带砂岩由于受到周期性水压渗透的影响,其物理力学特性随时间损伤劣化,导致岸坡稳定性降低。开展了周期性孔隙水压力损伤砂岩的不排水三轴压缩试验,分析了砂岩强度、变形及脆性特征演化规律,讨论了细微观结构劣化机制。结果表明:砂岩峰值强度随着孔隙水压作用周次的增大而减小,且强度劣化度随围压增大逐渐降低。随着孔隙水压作用周次增大,黏聚力和内摩擦角分别呈现指数式衰减和线性衰减,其中黏聚力下降是强度劣化的主要原因。弹性模量、破坏应变和Tarasov脆性指数均随孔隙水压作用周次增大逐渐降低,而随围压增大具有明显增强效应。破坏模式由单斜面剪切破坏发展至共轭剪切破坏,破裂角由67.20°逐渐减小至62.05°。周期性孔隙水压作用在裂隙尖端导致的应力集中和应力疲劳加剧了砂岩内部结构劣化,且不排水压缩过程中的孔隙水压力的增长进一步加剧了砂岩的损伤劣化,而围压作用导致部分渗流通道闭合,降低了砂岩的渗流损伤。Due to the influence of cycle water pressure permeation,the physical and mechanical properties of sandstone in the fluctuation zone deteriorate with time,which leads to a decrease in bank slope stability.Undrained triaxial compression tests were conducted on sandstone subjected to varying cycles of pore water pressure.The evolution of the deformation,strength,and brittleness index of sandstone were investigated,and the mechanisms of microstructural deterioration were discussed.The results show that the peak stress decreases with the increase of osmotic water pressure action cycle,and the strength degradation gradually decreases with the increase of confining pressure.With an increase in the number of cycles of pore water pressure,both cohesion and internal friction angle decrease exponentially and linearly,respectively,indicating that the decrease in cohesion is the primary cause of strength deterioration.The elastic modulus,failure strain and Tarasov brittleness index decrease gradually with the increase of pore water pressure action period,however there is a significant enhancement effect with increasing confining pressure.Moreover,the failure mode has evolved from single slope shear failure to conjugate shear failure,with the fracture angle decreasing from 67.2°to 62.05°.The stress concentration and stress fatigue caused by cyclical pore water pressure at the crack tip exacerbate the internal structural degradation of sandstone.Additionally,the increase in pore water pressure during undrained compression exacerbates the damage and degradation of the sandstone,while the confining pressure causes the closure of some seepage channels,reducing the seepage damage of sandstone.

关 键 词：库岸边坡 砂岩 应力-渗流耦合 周期性孔隙水压 脆性指数 损伤劣化 

分 类 号：TU441[建筑科学—岩土工程]