Theoretical Model And Calculation Method Of Saturated Water-heat Transfer In Fracture With Contact Area

Water-heat transfer theory and calculation of fractured rock has a wide application value in the actual problem such as nuclear waste disposal, but the existing model of fractured rock water-heat transfer theory and calculation method is based on parallel plane crack model, the effect of local wall contact on water-heat transfer in fractured rock is neglected. Therefore, according to different classification of fracture wall, the influence of fracture wall contact on local features of water flow and water-heat transfer characteristics and their effect on the heat transfer model for rock mass should be studied to build theoretical model and calculation method of fracture with contact area.The main work and achievements are as follows:(1)Hele-Shaw model is used to simulate fracture with contact area; numerical method is used to solve the Reynolds lubrication equation and the local pressure gradient distribution within the fracture with contact area is also obtained, so does the equivalent hydraulic aperture of fracture with contact area. The calculation results under different contact area rate and theoretical estimate are extremely matched.(2) Sensitivity analysis of main factors for the thermal equilibrium time between contact area and water in the fracture is made. When the fracture and water’s Bi number satisfies a given range, the thermal equilibrium time between contact area and water in the fracture is quite short, therefore, the instantaneous thermal equilibrium assumption between contact area and water in the fracture is verified.(3)The temperature distribution of the rock surrounding the fracture with contact area and water in the fracture relative to the time and water in the fracture along the x direction are obtained with the variation of contact area rate and fracture aperture and water flow rate, which can be concluded that the heat transfer in fracture with contact area will be slowed as the contact area rate and fracture aperture becomes lower and water flow rate becomes slower.(4)For the different types of cross section of contact area, using numerical calculation method, the ratios between the equivalent hydraulic aperture and natural aperture of fracture with contact area are obtained when the cross section of contact area is oval or square or rectangular; the modification methods of rough fracture’s aperture are also studied.