Experimental Study On The Fluid-solid Coupling Permeability Of Fracted And Broken Rock Sample

In the process of coal driving or backstopping, mining rock happens fracted and broken phenomenon, it will induce dynamic disasters, such as water inrush, coal and gas outburst. According to the research method and the seepage characteristics, Mining rock seepage is divided into two parts, fracted rock seepage and broken rock seepage. The study on fluid-solid coupling permeability of mining rock has important engineering significance to reduce the mine disasters and ensure the safety of mine production.In the study of fracted rock seepage, by indigenous height adjustable coal sample preparation device(ZL:201420165076.5), using the method of sand thickness control the thesis makes circular thin plate specimens with different porosity, RSM-SY7 automatic ultrasonic measuring instrument with foundation piles and more cross-holes is used to measure and mark the values of porosity. Permeability test in the process of bend and deformation of thin circular plate specimens under axial compression is carried out by DDL600 electronic universal testing machine and self-developed infiltration testing device; the axial compressive strength and initial permeability of the circular thin plate specimens caused by porosity are investigated; time difference between axial load and peak of seepage flow, caused by the porosity, in deformation process of the circular thin plate bending specimen, is also explored; The permeability variation of circular thin plate specimens in the process of bending deflection is also studied. The result of the tests indicates When the porosity of the sample is becoming larger, the axial loadpeak value of Fmax emerges prior to the flow of Q peak. Conversely, the flow of Q peak emerges prior to the axial loadpeak value of Fmax.In the study of broken rock seepage, the thesis studies the flow characteristics of a variety of mineral crushing rock samples and mixed broken rock sample: The steady-state osmosis penetration tests were carried out on broken sandstone, broken mudstone, broken coal gangue and mixed broken rock sample to analyze the influence of the particle size, effective stress and porosity on broken rock permeability parameters. The experimental results show that with the increase of the porosity, the broken rock permeability increases, but Non Darcy flow ? factor decreases, and in the larger porosity(more than 0.4 or so) the magnitude of permeability increase is bigger, but in the smaller porosity(less than 0.35 or so) non Darcy flow ? factor changes greatly; With the increase of porosity, variations in the permeability of single samples are bigger than mixed samples, and on the basis of different particle size, the mixed sample of non Darcy ? flow factor is not necessarily greater than the single sample.Broken coal and rock porosity are continuously influenced by mining pressure in the process of mining. If the porosity continuously decreases, the surrounding fluid pressure will continuously increase. It will become an important cause of coal mine disasters, such as water inrush, coal and gas outburst, through the loading ways of continuously changing axial displacement, the infiltration rules of fractured sandstone are explored in the process of the continuous variation of porosity. The experimental results show that with the increase of osmotic pressure difference, non Darcy flow β factor and acceleration coefficient show a overall trend of decrease after the first increase in the process of continuous variation of porosity.The limitation of test instruments led to the two problems: fracted rock seepage test do not consider the effect of confined water and broken rock seepage test cannot control confining pressure. According to the two problems, this thesis puts forward the corresponding design of device and solutions.