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Shear behaviors of granite fractures immersed in chemical solutions
Abstract Highly mineralized and acid/alkaline groundwater is critical to the short- or long-term stability of fractured rock masses in geological engineering. Understanding the impact of water-rock interactions on mechanical properties of fractured rock masses is important but challenging. This study investigated the physicochemical interactions between chemical solutions and granite fractures which can directly control the mechanical behaviors of fractured rock masses. Direct shear tests were performed on artificial granite fracture samples immersed in chemical solutions with different pHs for 30 and 150 days. The results show that the solution of pH = 2 has the most significant influence on fracture shear properties, followed by the solutions of pH = 12 and pH = 7. The deionized water has the minimal influence on fracture shear properties. The shear properties of fractures immersed in acid and alkaline solutions are sensitive to immersion time, whereas the shear properties of fractures immersed in neutral solutions are not significantly affected by immersion time. The weakening mechanisms of the water-rock chemical interaction are different in different chemical solutions. Dissolution mainly works in acid solutions, whereas the competing minerals dissolution and precipitation/crystallization occur in alkaline solutions. This is why alkaline solutions have less significant influence on fracture shear properties than acid solutions.
Highlights Shear behaviors of granite fractures immersed in different pH solutions are studied. The mechanisms responsible for fracture weakening induced by physicochemical water-rock interactions are discussed. A coefficient to evaluate the effect of physicochemical water-rock interactions on fracture peak strength is proposed.
Shear behaviors of granite fractures immersed in chemical solutions
Abstract Highly mineralized and acid/alkaline groundwater is critical to the short- or long-term stability of fractured rock masses in geological engineering. Understanding the impact of water-rock interactions on mechanical properties of fractured rock masses is important but challenging. This study investigated the physicochemical interactions between chemical solutions and granite fractures which can directly control the mechanical behaviors of fractured rock masses. Direct shear tests were performed on artificial granite fracture samples immersed in chemical solutions with different pHs for 30 and 150 days. The results show that the solution of pH = 2 has the most significant influence on fracture shear properties, followed by the solutions of pH = 12 and pH = 7. The deionized water has the minimal influence on fracture shear properties. The shear properties of fractures immersed in acid and alkaline solutions are sensitive to immersion time, whereas the shear properties of fractures immersed in neutral solutions are not significantly affected by immersion time. The weakening mechanisms of the water-rock chemical interaction are different in different chemical solutions. Dissolution mainly works in acid solutions, whereas the competing minerals dissolution and precipitation/crystallization occur in alkaline solutions. This is why alkaline solutions have less significant influence on fracture shear properties than acid solutions.
Highlights Shear behaviors of granite fractures immersed in different pH solutions are studied. The mechanisms responsible for fracture weakening induced by physicochemical water-rock interactions are discussed. A coefficient to evaluate the effect of physicochemical water-rock interactions on fracture peak strength is proposed.
Shear behaviors of granite fractures immersed in chemical solutions
Shang, Delei (author) / Zhao, Zhihong (author) / Dou, Zihao (author) / Yang, Qiang (author)
Engineering Geology ; 279
2020-10-15
Article (Journal)
Electronic Resource
English
Effect of Immersion Duration on Shear Behavior of Granite Fractures
| Online Contents | 2021