The Research On Building Gas High Quality Channel Of Xuandong 2# Mining

Gas as the main associated resources, is one of the most important factors in the past which threaten the safety of coal production, and it is also serious waste and underestimated. With the intensification of green coal mining has been paid more and more attention, simultaneous extraction of coal and gas is imperative.In this paper two Xuandong two mine as the engineering background, used theoretical analysis, numerical simulation, field monitoring and other means, for the simultaneous extraction of coal and gas in the hot research problems in the theory and technology, the research on Mechanism of the surrounding rock of the butterfly shaped plastic zone formation, mechanism of formation in drilling surrounding rock "butterfly the plastic zone based on intervention method of high quality gas channel reconstruction of key mining intervention methods and key artificial channels, and gas of two Xuandong two mine 302 working face extraction concentration of whole process monitoring of gas concentration and the working surface and drill field distance relationship, rationality" butterfly of surrounding rock plastic zone ".The main research achievements are as follows:(1) The problem of elastic circular in mechanics as the basis, combined with the theory of partial plastic mechanics, established the "butterfly of surrounding rock plastic zone" theory, reveals the mechanism of the formation and distribution of surrounding rock of "butterfly shaped plastic zone", which provides a theoretical basis for building high quality gas channel;(2) In the "butterfly of surrounding rock plastic zone" theory as the foundation, study the formation of mining stress environment influence of the shape of plastic zone of surrounding rock of borehole butterfly, put forward the concept of high quality gas channel, set up the length of the working face through rational planning of mining activities, the key mining intervention method the surface height and working face coal pillar construction quality parameters such as gas;(3) In Xuandong mine as an example, analyzes the mine gas drainage borehole in the experience of mining influence and did not experience rule of gas concentration under the influence of mining, to verify the rationality of drilling surrounding rock "butterfly shape quality of gas channels" theory based on the method of building.The problem of elastic circular hole in mechanics as the basis, combined with the theory of partial plastic mechanics, established the "butterfly of surrounding rock plastic zone" theory model, on this basis, to reveal the mechanism of the formation and distribution of surrounding rock of "butterfly shaped plastic zone", and provides a theoretical basis for the Gou Jianyou gas channel, the main conclusions obtained are as follows:(1) Established the theory of rock drilling model, through the analysis of the mechanical model, the surrounding rock stress field in uniform and non-uniform gravitational field under deviatoric stress solution; the surrounding rock of borehole deviation distribution of stress field, the mining depth and the maximum and minimum principal deviator stress is direct proportion the relationship between rock location, polar coordinates(R, 0) and the maximum and minimum principal deviator stress show transverse "eight" shape and the "top" shaped distribution;(2) The surrounding rock of the radius of plastic zone under non pressure calculation formula of stress field, revealed in the non equal stress field in surrounding rock "butterfly shaped plastic zone distribution;(3) Analysis of the lateral pressure coefficient, cohesion and internal friction angle of C and the radius of the hole drilling effect of R on the distribution of plastic zone of surrounding pressure. When the lateral pressure coefficient is not equal to 1, drilling and plastic zone of surrounding rock are showing "Butterfly"- shaped distribution, and a /1(when >1) or 1/(when <1) the greater the ratio, the plastic zone of the surrounding rock of the borehole "Butterfly" pattern is more obvious; the more cohesive force c small hole rock plastic zone scope is big, and the "Butterfly" pattern is more obvious; the internal friction angle is smaller in surrounding rock plastic zone is larger, and the "Butterfly" pattern is more obvious; the greater the radius of the hole drilling surrounding rock plastic zone is larger, and the "Butterfly" pattern is more obvious.In the "butterfly of surrounding rock plastic zone" theory as the foundation, study the formation of mining stress environment influence of the shape of plastic zone of surrounding rock of borehole butterfly, put forward the concept of high quality gas channel, set up the length of the working face through rational planning of mining activities, the key coal mining work surface height and intervention methods the working face of coal pillar construction quality parameters such as gas through the numerical simulation results show that:(1) In the working face length is less than 200 m or greater than 200 m, high stress ratio with shape of saddle shaped or hump shaped, such high stress ratio is not conducive to gas drainage borehole layout. When the length of the working face in the 200 m, the high stress ratio with horizontal elliptical distribution, is conducive to the layout of gas drilling, gas drilling can be arranged in the most high stress ratio in band.(2) Did not show significant stress unloading region in coal floor strata under mining influence, no, can not form a butterfly shaped plastic zone of surrounding rock stress environment, is not conducive to the expansion of the plastic zone of the surrounding rock of the borehole gas drainage drilling, so it should be avoided as far as possible in the floor of coal pillar region.(3) Shall not force ratio with high shape with the mining height of working face change and change, high stress ratio with the maximum ratio does not change with the mining height and changed obviously. At the same time, high position and force ratio does not change with the mining height. Therefore, the mining height does not have a greater iMPact on high stress ratio with the size and distribution.(4) Co MPared to the length of the working face and the face size of coal pillar in the mining height of working face of high iMPact force ratio with larger. Therefore, for the planning of mining parameters to achieve the construction of high quality gas pass, can be considered the main from two aspects of planning and the length of the working face and the working face of coal pillar size.The intervention method of high quality gas channel reconstruction method includes key coal mining method of intervention methods and key artificial channel. Coal mining method the key intervention through reasonable planning of mining engineering, construction is conducive to building a high quality gas channel stress environment, intervention methods mainly includes two key artificial channel drainage borehole layout layer and drainage borehole spacing. Drilling rock plastic zone method, explores the method of determining borehole layout layer and hole spacing reasonable, the results of the study show that:(1) In the high stress ratio under different lithologies zone, plastic zone of surrounding rock are showing butterfly shape. When other parameters under certain conditions, the maximum radius of surrounding rock plastic zone and rock boundary cohesion are negatively correlated, in the rock cohesion increases to a certain value, the maximum radius varies slowly; when the other parameters under certain conditions, the maximum radius of surrounding rock plastic zone and rock boundary internal friction angle was negatively correlated, in internal friction angle of rock increases to a certain value, the maximum radius varies slowly.(2) Drilling reasonable layer selection are divided into two kinds: the mining of coal quality hard, borehole in coal seam mining; the coal quality is soft, borehole stability of coal mining under the rock in the vicinity.(3) Determine the hole spacing on the basis of the borehole surrounding rock plastic zone boundary the maximum radius and the azimuth angle. Borehole in coal seam, the hole spacing: maxH ?2Rcos?; borehole layout in adjacent rock stability, hole spacing: maxH ?2(h?d) / tan?.Based on the study of drilling surrounding rock "butterfly shaped plastic zone" theory and the quality of gas channel construction method, this chapter in Xuandong mine as an example, introduces the situation of mine gas drainage, coMParative analysis of the mine gas drainage borehole in the experience of mining influence and did not experience the gas concentration the law under the influence of mining, to verify the rationality of "butterfly of surrounding rock plastic zone of high quality gas channels" theory based on the method of construction, according to the field monitoring results:(1) Through the analysis of the 302 working face gas drainage concentration found: the distance from the working face gas concentration and the drill field distance shows the inverse, namely face distance drilling field more far, the gas concentration is smaller, the working face distance drilling field near the gas concentration.(2) The relationship between the distance from the working face gas concentration and drilling field to verify the rationality of drilling surrounding rock "butterfly shaped plastic zone" theory. The working face is far from drilling, drilling in theoriginal rock stress, surrounding rock around almost no plastic zone, resulting in each borehole gas concentration is small; when the mining face gradually close to drill boreholes in the field, the stress field of mining stress environment in mining, surrounding rock plastic zone of butterfly, is conducive to the gas drainage, the gas concentration increased gradually.This paper studies the surrounding rock of the butterfly shaped plastic zone "theory, the key mining intervention methods and key artificial channel intervention methods and put forward on the basis of high quality gas channel reconstruction, provides a new thinking and a new method of mining, simultaneous extraction of coal and gas for gas drainage.