Calculation Methods And Applications Of 3D Seepge And Heat Transfer In Fractured Rocks

In the field of underground engineering,such as high-level waste disposal,geothermal energy extraction and petroleum resource mining,the coupled processes of hydrological,thermal,mechanical and chemical behaviors in fractured rocks are involved.This dissertation focuses on the three-dimensional seepage and heat transfer in multi-scale fractured rock,including the semi-analytical model and method of seepage and heat transfer in the parallel arbitrary fractured rock,the numerical simulation of seepage and heat transfer in the random rough fractured rock,the equivalent continuous method of permeability of the random fractured rock,the local artificial boundary method for the numerical analysis of seepage and heat transfer in the geothermal doublet system,and the analytical model and method of thermo-mechanical coupling processes in the far-field of high-level radioactive waste disposal system.The main achievements are as follows:(1)For the three-dimensional seepage and heat transfer in enhanced geothermal system and high-level radioactive waste disposal system with fractures sparsely distributed,a semi-analytical model and method are proposed considering twodimensional convective heat transfer of fracture water and three-dimensional conduction heat transfer of rock,and improves the theoretical study on the temperature calculation of three-dimensional seepage and heat transfer in fractured rock.(2)For the three-dimensional seepage and heat transfer in enhanced geothermal system with fractures randomly distributed,an equivalent continuous model and method are proposed describing the spatial variability of the permeability of random fractured rock,and improves the theoretical research on the equivalent permeability of threedimensional fractured rock.(3)For the three-dimensional seepage and heat transfer in geothermal system,a local artificial boundary condition is proposed by Laplace transform,Fourier transform and rational integral approximation,and has good numerical stability and high computational efficiency,and improves the theoretical research on the boundary treatment of threedimensional seepage and heat transfer.(4)For the far-field thermal-mechanical coupling problem of high-level radioactive waste disposal system,a time-varying longitudinal linear heat source analytical model and method are proposed considering the distribution characteristics of thermal load,and improves the theoretical study on far-field thermal-mechanical interact analysis of highlevel radioactive waste disposal system.