Multi-Field Coupling Characteristics In The Process Of Floor Water Ingestion

With the depletion of shallow coal seam resources in China,the exploitation of deep coal seam resources has become a trend of development.Deep seam water inrush of coal seam floor is the result of multi-field coupling of seepage field,stress field and temperature field.Therefore,from the perspective of multi-field coupling,it is of great theoretical and practical significance to study the deformation and water inrush mechanism of the bottom plate.The deep rock mass is in a special environment of high ground stress,high pressure water pressure,and high ground temperature.According to the data of massive water inrush in coal mines,the factors influencing the water inrush from the coal floor include the water richness of the aquifer,geological structure,mine pressure,and aquifer.Water pressure,water resistance of the barrier layer,and ground stress.Based on the analysis of the theory of "lower three belts",the mechanism of water inrush under the action of confined water is summarized.Based on the analysis of the theory of "lower three belts",the mechanism of water inrush under the confined water is summarized.Based on the basic theory of thermal fluid-solid multi-field coupling,the multi-field coupling interactions are analyzed.The mathematics description of multi-field coupling of floor water inrush is further perfected,and a multi-field mathematical model of seepage-stress-temperature coupling is constructed.According to the geological conditions of the mine,a fluid-solid coupling and thermal fluid-solid multi-field coupling simulation model was established,and the model was solved with COMSOL Multiphysics software.The specific simulation can be divided into four situations:?When the aquifer water pressure remains unchanged,the working surface The distribution of top and bottom stress and the water pressure received by the bottom plate when advancing to different distances;?The influence of water pressure of different aquifers on the coal floor under the same excavation footage.?The distribution of temperature field and seepage field during the process of advancing the working surface when the water pressure is constant;?The distribution of temperature field and seepage field under the effect of different water pressure when the digging footage remains unchanged.The results show that:?The water pressure in the aquifer under the coal seam floor gradually increases with the advancement of the working face,and the stress distribution is mainly concentrated near the working face and the open-cut eye,which is in line with the actual coal seam mining conditions.?For the same excavation footage,the water pressure under the coal bed floor increases with the increase of water pressure,and the effect of the coal bed becomes more obvious as the work surface progresses.? As the work surface continues to advance,the isoline of the temperature field distribution becomes more and more dense at the work surface,and the temperature change is greater.When mining close to the fault,the temperature shows an upward convex trend near the fault,and the nearer the fault is,the more obvious the upward convex trend is,and the seepage velocity in the fault increases gradually.?Keep the driving surface distance unchanged.As the water pressure changes,the isotherm is more densely distributed on the working surface.When the water pressure is low,the isotherm is more stable on the fault;when the water pressure is higher,the temperature is isothermal.The line appears convexly distributed at the fault,and the isotherm in the temperature field moves upward as the water pressure increases.