Study On Borehole Location And Sealing Technology Of High-level Extraction Based On The Development Law Of Mining Fissures In Overburden

Gas is formed in the process of geological movement and evolution of coal.It is the geological gas stored in coal seam and surrounding rock according to the complex evolutionary action of tens of millions of years or even hundreds of millions of years.Coal mining and gas emission are concomitant.How to control gas effectively becomes one of the important directions of coal mine safety guarantee.Gas extraction technology is an important means and measure to control the harm of gas in coal mines.By systematically studying the development process of mining-induced fractures in coal mines,it is easy to determine the layout of the high boreholes so as to carry out efficient gas extraction.Firstly,the physical properties of the gas foundation at the 9305 working face of Anshun coal mine were studied by measuring points,and the gas content,initial velocity of gas emission,porosity of coal and rock,gas adsorption constant,gas permeability coefficient of coal seam,and gas permeability of coal and rock were measured.The dynamic two-dimensional(2D)mining subsidence prediction model of overburden is developed and the relevant dynamic subsidence parameters are determined.Based on the dynamic theoretical calculation of overburden subsidence and horizontal displacement of 9305 working face,the subsidence and horizontal movement of overburden point have experienced a dynamic process from beginning to accelerating,then decelerating and finally stopping.The measured method of the vertical hole displacement meter on the ground was continuously observed within the range of 104 m from the upper part of the working face to the ground,which verified the correctness of the established model.Established through theoretical derivation,the porosity,total strain and mining the numerical relationship between the permeability change,developed the "porosity-full strain-permeability mathematical model,and uses this model to 9305 working face of overburden rock permeability was calculated,the results show that the mining overburden rock under the influence of point is passed by the original state to a state of tension expansion,to compressive shrinkage deformation process state transitions and gradually stabilized;At the same time,the fractures in the overburden have undergone a dynamic process from gradual development to gradual closure.With the advance of the working face,the high tensile expansion zone and the compression zone in the overburden behind the face are in a state of constant alternation.Based on the evolution analysis of mining influence of permeability and porosity,it is comprehensively determined that the deformed overburden with potential gas accumulation in the overburden of 9305 working face is 8-45 m deep in the gob direction of the working face and 32.16-56.84 m vertical height.In order to governance the gas problem in 9305 working face,we put forward the implementation in the best gas accumulation area high drilling for gas extraction,this paper on the hole sealing process put forward the development of the constant pressure bursa bag hole sealing device,cooperate the solidified grout hole sealing operations,the results show that the test hole in the gas concentration in the observation period of a month is always greater than 10%,compared to before the extraction technology of gas drilling of concentration effect is obvious,to verify the exactness of the extraction from horizon to determine and new hole sealing process effectively,to Anshan coal mine 9305 working face gas control work to lay a solid foundation.