Experimental investigation of seepage characteristics in porous rocks with a single fracture
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PAPER
Experimental investigation of seepage characteristics in porous rocks with a single fracture Lei Gan 1,2 & Zhenzhong Shen 1 & Ming Xiao 2 Received: 16 January 2020 / Accepted: 3 August 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract An experimental investigation of seepage characteristics in porous rocks with a single fracture is presented. A seepage system was developed and assembled in the laboratory using two experimental setups. Tests were conducted to quantify the effects of influent pattern, fracture aperture (B), coefficient of permeability of the porous medium (k), hydraulic gradient (J), and water temperature (T) on the seepage characteristics of a porous concrete matrix with a fracture; the porous concrete, with controlled characteristics, was designed to simulate porous rock. The mechanisms of seepage exchange between the porous media and the fracture are discussed, and a new formula for describing the seepage mechanism in a porous rock with a single fracture is proposed. The results showed that B, k, and influent pattern had significant effects on the seepage between the fracture and the porous concrete. The amount of effluent exiting the fracture was greater than that exiting the porous concrete blocks. The proposed model indicated that when B was less than 3.0 mm, the variation in fracture aperture had a significant influence on the effluent from the fracture, while its influence was relatively small when B was greater than 3.0 mm. When k was less than 1.0 cm/s and B increased to 4.8 mm, seepage exited only via the fracture. The proposed mathematical model can be used to effectively estimate the seepage through porous rocks with a fracture. Keywords Fractured rocks . Seepage characteristics . Laboratory experiments . Fracture aperture . Coefficient of permeability
Introduction Fractured rock mass is a complex geological body composed of rock matrix and discontinuous structural planes such as joints, fractures and faults. These discontinuous structural planes, along with rock pores, are the main storage space and migration channels for groundwater, oil, and natural gas, and significantly affect the seepage characteristics of the fractured rock mass (Miao et al. 2009; Ju et al. 2013). Many seepage-induced disasters in geological engineering such as water inrush accidents of coal mines, dam failures, and instability and failure of rock slopes, were closely related to the * Lei Gan [email protected] * Zhenzhong Shen [email protected] 1
College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, China
2
Department of Civil and Environmental Engineering, Pennsylvania State University, University Park, State College, PA 16802, USA
groundwater seepage in fractured rock mass (Berkowitz 1993; Adler and Thovert 1999; Chen et al. 2000; Yan et al. 2015). Therefore, the study of seepage characteristics of fractured rock mass is of both great theoretical and engineering significance for the prevention and control of seepage disasters in geo
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