Study On Improving Sealing Efficiency Based On Laws Of Surrounding Rock And Tectonic Crack

Gas extraction is an important technical means of mine gas control,the quality of hole sealing and the effective extraction period determine the effect of mine gas drainage.On the basis of summarizing the present situation of drilling gas extraction and sealing technology and materials at home and abroad,on the basis of the theory of damage and fracture mechanics of coal and rock,based on the dual structural properties of coal pore and fissure,this paper studies the development and expansion mechanism of surrounding rock fissure of gas-bearing coal drainage hole.The factors affecting the sealing of borehole and the way of leakage of borehole surrounding rock under the influence of mining stress are analyzed.In order to study the crack development range of roadway and borehole surrounding rock in coal seam gas extraction,a corresponding physical and mechanical model is established based on the field data of Hebi mine.This paper studies the physical and mechanical properties of the rock mass around the roadway and borehole,and combines the numerical simulation software to get the model of the stress-strain and pressure-relieving zone around the borehole.At the same time,considering the creep effect at the later stage of the drilling hole,the development range of surrounding rock fissure under the influence of creep effect is obtained,the reasonable sealing position and the length of sealing hole are determined,which lays a theoretical foundation for improving the effect of sealing hole.This paper expounds the technical principle,the device structure and the sealing process of the radial expansion method,and studies the corresponding sealing device and the sealing technology,and obtains the remarkable extraction effect in the Hebi three mines by using the parameters of the sealing hole obtained from the previous paper.The field application shows that the radial expansion sealing method is applied to the drilling gas extraction in the 3202 working face of Hebi mine,compared with the mine-side intact hole technology,the average single hole gas extraction concentration and the average single hole gas extraction pure flow rate increased 72% and 59.7% respectively,and the radial expansion method showed good sealing effect in the engineering test.