Analysis Of Physical Experiment Of Drill Cuttings And Factors Affecting Coal Drilling Relief

Coal burst is a serious coal mine geological disaster.The coal drilling relief method has a small workload,convenient construction,and a rapid construction speed,and is a method that is being applied to pressure relief.Drilling parameters are an important factor influencing the pressure relief effect of drillings.This paper studied the effect of drilling parameters on the pressure relief effect of drillings through the combination of theoretical analysis,numerical simulation and indoor testing.And in order to reduce the construction period and overcome the poor continuity of the traditional drill cuttings method,the relationship between the amount of drill cuttings and the drilling diameter and stress conditions was studied.The impact risk drill cuttings indicators were determined and applied at the engineering site.The main work is as follows:(1)Analyze the mechanism of coal drilling relief method to prevent coal burst,and derive the calculation formula of the stress and displacement around the drill and the calculation formula of drill cuttings under elastic state and elastic-plastic state.The simulation of drill cuttings was conducted to verify the correctness of the theoretical formula.The amount of drill cuttings increased with the increase of the diameter of the drilling,and it showed a quadratic polynomial law;The pressure increases linearly.(2)Uniaxial compression tests were performed on specimens with different parameters(drilling diameter,number of drill,number of drilled rows,and drilling arrangement).The test results systematically revealed the influence of these drilling parameters on the mechanical behavior of the specimens,including uniaxial compressive strength,elastic modulus,acoustic emission characteristics and failure modes.The test results were used to analyze the effect of different drilling parameters on the coal drilling relief.(3)Through the numerical simulation of the effect of different drilling parameters on the roadway surrounding coal,the stress characteristics and plastic zone distribution of roadway surrounding coal with different parameters are combined.With the increase of the diameter,the drilling pitch decreases and the drilling depth increase,the effects of coal drilling relief are getting better and better.In addition,for different drilling arrangements,the effect of coal drilling relief when drilling a single row is better than that of drilling three-flower arrangement and drilling double-row arrangement.When definite parameters for site pressure relief drilling,the pressure relief effect cannot be only pursued,excessive pressure relief should be prevented,and the roadway deformation and destruction are serious.(4)The main factors influencing the occurrence of coal burst on the west side of the mining area in the west of the 10th slot of Da anshan are analyzed.The drilling parameters were determined based on the combination of tests,numerical simulation results and on-site construction conditions.The rock burst risk distribution was divided by the amount of drill cuttings in the pressure-relief drill hole and the dynamic manifestation phenomenon during the construction process,and the middle impact danger zone and high impact risk were analyzed.The area was drilled for encryption to ensure the safe production of the working face and the application effect was good.