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Abstract The characteristics of water flow and heat transfer in fractured rocks is an important component for the performance and safety evaluation of high-level radioactive nuclear waste repositories. A meter-scale physical modelling experiment is conducted to study the behaviour of flow and heat transfer in multi-fractured rocks with variable heat source temperature and water flow velocity. The granite rocks are taken from the Beishan area in Gansu province，which is being investigated as potential site for the high-nuclear waste repository in China. The fractured rock model of 150.25 cm×90.4 cm×30 cm(height×width×thickness) consists of 18 granite rocks with 2 vertical fractures and 2 horizontal fractures；a heater is placed on one side of the fractured rock model and thermal sensors and pressure sensors are installed in the interior. The experimental results reveal that：(1) since there exists a distance between the heat source and the vertical fractures，heat conduction and fracture water flow are not significantly coupled until after one hour of the experiment；(2) at the junction of vertical and horizontal fractures，due to local heat convection，the temperature of water in the vicinity is significantly increased；(3) the range of influence of the heat source is larger，and the time for asymptotically approaching steady-state is longer，for higher heat source temperatures and lower water velocities in the fractures；(4) vertical fracture adjacent to the heat source controls the temperature distribution in the model，and the horizontal fractures may increase the range of influence of the heat source；(5) under the given conditions，with the vertical fracture water temperatures well below 100 ℃，there is little effect on the water pressure.
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Received: 10 September 2010
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2011, Vol. 30 
