Abstract: Approximate analytical solution and finite element solution for the water flow of single fracture and variable water temperature considering the impact of water temperature on rock fracture seepage have been deduced. Based on the analytical formulas, the seepage numerical equations for two-dimensional fracture network under variable water temperature are formed, which apply to the approximate analytical methods and sub-structure method to variable water temperature analysis of fracture network seepage respectively. Some results can be found as follows. (1) The water head and the hydraulic gradient in single-fissure are nonlinear dependence. Seepage curve is convex curve when the current flow from the higher temperature area to the lower temperature area. In the condition, the water head slants low under liner seepage simplification. On the contrary, seepage concave is convex curve when the current flow from the lower temperature area to the higher temperature area, and the water head slants high. (2) In a single fracture, the hydraulic gradient is smaller in higher temperature area and is larger in lower temperature area. Higher the average water temperature of fracture is, and faster the flow velocity is. There is deflection effect caused by temperature in the fracture network. In the crossing nodes fluid tends to flow to the higher temperature area. Consequently, the effect of temperature change to seepage should be taken into account in the region of high temperature and high temperature gradient.

Key words: fracture network of rock mass, seepage, sub-structure method, variable water temperature, flow deflection effect caused by temperature