中文摘要：

为了研究酸性干湿循环对泥质砂岩强度特性劣化的影响,以重庆三峡地区某边坡的泥质砂岩为研究对象,对不同酸性（p H=3）干湿循环次数n（0,1,5,10,15,20）作用的泥质砂岩试件进行室内单轴、三轴压缩试验及电镜扫描观察,并借助离散元软件PFC~（2D）对三轴压缩试验峰值强度状态时试件的颗粒接触、裂纹分布进行模拟。研究发现,泥质砂岩的单轴抗压强度σ、弹性模量E、黏聚力c、内摩擦角Φ和三轴抗压强度σ′都随n的增加而降低。n=1时σ,E,c和Φ的阶段劣化度最大,酸性干湿循环作用对c的劣化影响要大于对Φ的劣化影响。泥质砂岩微细观形态随n的增加大致经历整齐致密、多孔团絮和开裂紊流3个阶段。此外,在三轴压缩试验峰值强度时,n的增加对泥质砂岩试件颗粒接触网络,微裂纹的发育、试件破坏模式等都影响显著。

英文摘要：

In order to understand the effect of dry-wet cycles with acidic wetting fluid on the strength deterioration of shaly sandstone,the shaly sandstone at the slope of the Three Gorges Area in Chongqing was selected for study. The shaly sandstone specimens were exposed to n dry-wet cycles with an acidic solution（p H = 3）（n is the number of cycles）. The specimens were treated through indoor uniaxial and triaxial compression tests and were scanned with an election microscope. The discrete element software PFC~（2D） was used to simulate the particle contact and crack distribution of the specimens（n varies） at the peak strength in the triaxial compression test. It was found that the uniaxial compressive strength（σ）,elastic modulus（E）,cohesion（c）,internal friction angle（Φ） and triaxial compressive strength（σ′） of the specimen decreased with the increase of n. When n=1,the strength parameters show the greatest degree of deterioration. The dry-wet cycles have a greater impact on the deterioration of c than on Φ. As n increased,the shaly sandstone was changed from a well-organized dense structure to porous floccules and then to a turbulent flow according to the microscopic observation. In addition,when the strength reached its peak value in the triaxial compression test,the increase of n had a significant effect on the contact network of particles,the microcrack development and the failure mode of the shaly sandstone specimens.