The effect of dry-wet cycles with acidic wetting fluid on strength deterioration of shaly sandstone
LIU Xinrong1，2，LI Dongliang1，2，WANG Zhen1，2，ZHANG Liang1，2
(1. School of Civil Engineering，Chongqing University，Chongqing 400045，China；
2. Key Laboratory of New Technology for Construction of Cities in Mountain Area，Ministry of Education，Chongqing University，Chongqing 400045，China)
Abstract：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(pH = 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 PFC2D 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(?)，elastic modulus(E)，cohesion(c)，internal friction angle(?) and triaxial compressive strength(?′) 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 ?. 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.
2016, Vol. 35 
