Abstract
The water-sediment two-phase seepage in coarse fractures is one of the major factors to trigger mine water inrush disasters. Based on seepage mechanics theory, a mechanical model of the water-sediment two-phase seepage in coarse fractures was established. An experimental system was also developed to study the seepage characteristics under various conditions. The relationships between the absolute value of the pressure gradient and the seepage velocity were analyzed during the test process. The nonlinear characteristics of the seepage test were revealed. In addition, variation laws of the absolute value of the pressure gradient with the sand volume fraction and the sand particle size were illustrated, which were related to the loss of pressure during the particle movement. The impacts of the sand volume fraction and the sand particle size on the equivalent fluidity and β -factor of non-Darcy flow were discussed and analyzed. It was determined that the local turbulence was the main reason for the change of nonlinear variation characteristics of seepage parameters.
Highlights
Water inrush is one of the major disasters affecting coal mine safety production
Water-sediment two-phase flow in course fractures is the precursor of mine water inrush disasters
Many scholars used numerical calculation methods to reveal the complete process of water-sediment two-phase flow, and they adopted the software, such as ANSYS, FLAC, PFC, and COMSOL, to study the seepage fields and stress fields [9,10,11,12]
Summary
Water inrush is one of the major disasters affecting coal mine safety production. It causes the direct cost of tens of billions of yuan every year in China. It is the key to study seepage characteristics of the water-sediment mixture to reveal the mine water inrush mechanism. The formation of fissure channels and the seepage of water-sediment mixture are two core factors of mine water inrush disasters. With the development of test equipment and the signal acquisition system, water-sediment two-phase seepage experiments in coarse fractures were carried out and a series of research results were achieved [14,15,16]. Studies on the water-sediment seepage process in coarse fractures, scholars mainly study the factors affecting the seepage characteristics, including fracture roughness, fracture aperture, sediment concentration, and sand particle size [17,18,19,20,21]. The test results are aimed at revealing the water and sediment inrush mechanism and providing references for water-sediment inrush disaster prediction and control
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