Study On Coal Seam Gas Pressure Measure Technology Of Grouting With Pressure Drilling Sealing Base On The Cement Composite Materials

Apart from the human factor,one of the important reason of low success rate of gas pressure measurement is the gas pressure measuring drilling sealing is not tight.At present the main problems of drilling sealing are: the unreasonable drilling sealing starting position,difficult to determine the drilling sealing length,unreasonable drilling sealing technology and grouting pressure,drilling sealing materials are not apply to block fracture in roadway surrounding coal and rock.According to the numerical simulation,laboratory experiment and field work,this paper studied the strain and creep effect of roadway surrounding coal and rock stress,drilling sealing grouting material,drilling sealing starting position and drilling sealing depth,the main results as follows:(1)Based on the analysis of physical and mechanical property of roadway surrounding coal and rock,using numerical simulation software to simulate plastic zone and the stress and strain of roadway surrounding coal and rock,also,study the Chengzhuang coal mine coal roadway creep effect,it concluded influence of the creep effect of roadway to drilling sealing.It concluded that the reasonable drilling sealing starting position(drilling inward 6.8m)and length(11m).To improve the drilling sealing effect,it established the theoretical basis to the gas pressure measure.The deeper the buried depth and the greater the cross section of roadway is obtained,the greater the influence of the elastic and plastic zone,therefore we must consider roadway section factors and burial depth to the influence of drilling sealing starting position and the length of drilling sealing.(2)Based on the numerical simulation to the stress and strain around borehole,it conclude the stress and strain model around borehole.When the drilling sealing distance is short,choose spherical grouting theory,When the drilling sealing distance is long,choose cylinder grouting theory,this paper adopt cylinder grouting theory to research,and drilling grouting model is established.(3)When the superfine sulphur aluminate grouting materials was modified by the early strength agent and water-reducing and set-retarding admixture,the performance was improved extremely.It selected the liquidity modifier agent and early strength agent and the ratio of hydrophilc agent on the surface of the coal.Adding several admixtures of sulphur aluminate grouting material could coagulate very fast and produce strong compressive strength after the injection of coal and has good fluidity before the injection of coal.Meanwhile,the superfine sulphur aluminate groutingmaterial also have very good effect for micro fissure filling,and volume did not appear shrinkage after solidification.(4)According to the numerical simulation and experimental validation of field drilling gas pressure measurement in Chengzhuang coal mine coal seam,the influence of roadway creep effect on drilling sealing starting position and the length of drilling sealing were studied.The modified sulphur aluminate cement grouting material is tested in field,the results show that the modified sulphur aluminate cement grouting material can fill coal crack,and the filling effect is good.The numerical simulation is used to determine the reasonable grouting pressure of 5 MPa.Adopt "two block and one inject" drilling sealing way to inject modified sulphur aluminate cement grouting material drilling sealing technology that it obtained the results of gas pressure measurement is0.24MPa-0.63 MPa,compared to previous field measured gas pressure numerical value is less than 0.1 MPa,increased 2-6 times,and the results of indirect calculation and determination of coal seam gas pressure of coal seam gas pressure is nearly same,relative error 2.04%-10.71%,average 5.85%.