Development And Application Of Strain-Porosity-Permeability Model Of Mining-induced Overlying Strata

In this paper,an overlying strata subsidence calculation mathematical model is built based on influence function method.The key parameters involved in the model are optimized.To prove the accuracy of the model,a surface observation station is set up.A simulation project of overlying strata using 3DEC is set up and gives reference to the mathematical model.Moreover,an overlying strata strain-porosity-permeability model is built based on the before-built subsidence prediction model.The following are mainly achievements:(1)An overlying strata subsidence prediction mathematical model are built based on the influence function method.The optimization of the key parameters involved in this model is made to make the model more realiable.An optimization is also made to the model,so the model is more applicalbe to calculate the movement of broken strata in caving zone.(2)Based on the model of overlying strata subisidence,an strain-porosity-permeability model about mining-induced strata is built to calculate the permeability of rock layers in vertical three different zones with different methods.(3)Setting up a surface observation station with two monitoring lines above the Yangmei 5th coal mine 8133 working face,the prediction results highly coincide with the observation.Using the 3DEC to simulate the movement of overlying strata and compare its simulation result with the model calculation,the calculated hights of caving zone are 57.3m and 55.87 m from 3DEC and mathematical model.(4)Calculating the subsidence and permeability distribution of overlying strata above coal seam to the height of 76.14 meters.The prediction results show that the height of caving zone is 55.87 meters and the permeability is high in rock layers bellow this height.Building the high drainage roadway in 52 m above coal seam,and its gas drainage production is perfectly excellent.Above 96.76% of total gas is extracted by high drainage roadway.In this paper,an overlying strata subsidence model is built based on influence function method.To confirm its accuracy,a surface subsidence observation station is set up.An overlying strata permeability model is also built based on the subsidence model,a high drainage roadway is designed and for deployment in underground working face.The gas drainage data show that the high drainage roadway plays a major role in working face gas drainage.