Experimental study on seepage characteristics of rock-like materials with consecutive and filling fractures

3D printing is used to produce different permeability structural surfaces, and rock-like samples are poured by moulds. The tests on permeability of rock-like samples with consecutive and filling fractures are carried out under loading and unloading pressures. The test system of gas permeability measurement for compact rock is applied in measuring the evolution of gas permeability of structural surface with different permeabilities under different confining pressures. The test results show that the permeabilities of samples with different filling fractures are different, but there is no difference in magnitude when the pressure changes. For example, under the confining pressure of 25 MPa, the permeabilities of samples with parallel fractures and combined fractures are the maximum and minimum values respectively. The variation curves of samples between permeability and pressure in loading process are higher than those in unloading process. The evolution of permeability of samples under different pressures is influenced by the geometrical characteristics of permeability structural surface. In the process of loading, the variation curves between stress sensitive coefficient and pressure of different samples change in a different trend. While in the process of unloading, the variation curves are almost the same and present a 'W' form, and the permeability stress sensitivity of rock-like samples with consecutive and filling fractures is influenced by the permeability structural surface.