Study On The Mechanism Of Partial Filling To Prevent Water Inrush From Floor

The Carboniferous Permian coal field in North China is the most important mining coal seam in the middle eastern part of China.With the decreasing of coal resources in the upper part of the Shanxi formation in the middle and eastern part of China,the lower group coal basement is directly covered with the weathering denudation surface of the Middle Ordovician,and the Middle Ordovician is thick limestone and rich in karst water.The coal system is composed of layers of thin layers of limestone.The interval between the aquifer and the floor of the coal seam 1s only a few meters to dozens of meters,and the karst fissure develops at the same time concealed a large number of fracture structures.The water pressure of the limestone is larger and the part can reach 7-10MPa.The conventional mining method is easy to induce the water inrush of the floor.In recent years,the researchers in China have put forward many ways to reduce the occurrence of water inrush disaster,such as depressurization,grouting and water plugging,and so on.However,because the pressure of the lower coal pressure is larger,with the continuous excavation of the working face,the water inrush disaster occurs again under the support of the support pressure and the pressure of the pressure of the bearing water.In this paper,using the method of treating the hard roof goaf with the tool column pillar support method,this paper puts forward the method of controlling the water inrush from the bottom plate with partial filling,taking the 9211 working face of the Bu village coal mine as the research background.Based on the mechanical derivation,numerical simulation and physical simulation,the paper studies the key problems of the partial filling prevention and control of the floor water inrush,providing the theoretical support for the prevention and control of the floor water inrush under the similar conditions.In this paper,by means of the theory of thin plate and the theory of"lower three bands" in elastic mechanics,this paper establishes a water inrush model with partial filling to prevent and control bottom plate,and derives the catastrophe criterion of water inrush in the water separated rock layer of the floor of partial filling mining.Through the numerical simulation of FLAC-3D,the influence of different parameter variables on the bottom plate failure depth and the pressure rise height of the confined water is synthetically analyzed.With the strength of the filling body and the filling rate,the change value of the floor displacement,the vector value of the flow and the height of the pressure water are gradually reduced,and the change value of the second wheel excavation is larger than that of the first round excavation.The stress distribution and the failure depth of the surrounding rock corresponding to different advancing distance are obtained.We have developed and tested the solid fluid coupled similar materials which can meet and use tihe bottom water barrier in the floor,and master the basic mechanical properties of similar simulated materials under different proportions and curing conditions.Through the simulation test of similar materials in the indoor,it is known that the water aquifer of the bottom plate gradually leads up the water along the supporting pressure and the pressure of the bearing water under the primary fissure in the process of filling and mining.At the same time,it extends to the layer.During the process of filling and filling,the overlying rock did not appear,and the overlying strata developed up from the roof to the top plate in the course of the excavation,which developed to the top of the roof about 6H height,and the fracture stopped developing.The overlying strata presented the whole bending and sinking phenomenon,and the upper stratum fracture gradually closed with the subsidence of the rock strata.Through the analysis of the on-line monitoring results of the compression capacity of the filling body in 9211 working face and the force on the filling body,it is found that the compression rate and stress of the filling body are smaller,and the filling support is more stable,and the safe and efficient reeovery of the eonfined water can be realized.