【作者】 蔡峰；

【导师】 刘泽功；

【作者基本信息】 安徽理工大学 ， 安全技术及工程， 2009， 博士

【摘要】 深孔预裂爆破为高瓦斯低透气性煤层增透,进而解决高瓦斯低透气性煤层瓦斯抽采难题提供了一条新的有效的途径。本文利用理论分析、数值模拟、现场试验、实际工程应用等方法系统地研究了深孔预裂爆破技术对低透气性高瓦斯煤层增透效应和促进煤层瓦斯抽采、防止煤与瓦斯突出的作用机理,指出了煤层硬度参数、煤层埋深参数以及相同煤层性质、爆破强度、埋深条件下,爆破孔孔径、爆破孔装药耦合系数以及爆破孔与导向孔的间距对爆破效果的影响,取得了以下研究成果:(1)得出了爆生应力波在煤体介质中的传播和衰减规律:①随着介质弹性模量的增加,爆生应力波随传播距离的衰减越来越小;②在传播距离小于大约10m时,应力波的衰减随着延迟时间的增加而减小,在传播距离大于大约10m以后,应力波的衰减随着延迟时间的增大而增大;(2)煤层硬度对爆破效果的影响较大:煤层的硬度越低,煤体越容易破碎,在爆生应力波的作用下,爆孔周围的煤体被极度破碎,形成粉碎圈,起到了缓冲应力波的作用,阻止了裂隙的进一步发育,因而煤层的硬度越高,裂隙发育越充分;(3)在相同爆破强度下,煤层埋深对深孔预裂爆破效果的影响较小,因而对于深部煤层,同样可以运用深孔预裂爆破技术进行卸压增透;(4)分析得出了爆破孔径对爆破效果的影响:随着爆破孔孔径的增大,爆孔周围煤体支承应力峰值逐渐增高,峰值距离逐渐增远,但是变化幅度很小,因此,在爆破孔径发生变化的时候,爆破孔径增大,卸压半径也相应增大,爆破卸压增透半径R_α在2.7～3.5m之间变化;(5)得到了装药耦合系数对爆破效果的影响:当耦合系数为B_l=0.6时,由于耦合系数较小,地应力曲线具有极大极小值,在炮孔上产生了应力集中,卸压效果微乎其微;当耦合系数B_l为0.8和1.0时,产生了较长的贯穿裂隙面,因此地应力峰值距离和卸压半径都比较大,卸压效果较好。因此,装药耦合系数对地应力卸除效果有着很大的影响;耦合系数大,卸压效果较好;(6)获得了爆破孔与导向孔的合理间距:当爆破孔与导向孔之间的距离L在3～4m之间时,卸压半径随孔间距的增加而增加,地应力的卸除效果也随之越好。从试验地点的效果看,深孔松动爆破试验增透效果显著提高了煤体透气性,提高了瓦斯抽采浓度和抽采量,有效松动半径为3～3.5m,表明对于低透气性高瓦斯煤层进行深孔预裂爆破增透技术是一种积极可行的方案,为实现低透气性高瓦斯煤层高效集约开采提供了可靠的技术保障。更多还原

【Abstract】 Deep-hole presplitting explosion provides an new and effective method to increase permeability of high gassy and low permeability coal seam, and farther solves the difficult problem of gas drainage in this high gassy and low permeability coal seam. In this dissertation, several researching methods, such as theory analysis and numerical simulation and on-field experiment as well as practical engineering application, are used to systematically study the promoting permeability effect of deep-hole presplitting explosion as well as action mechanism of promoting gas drainage and preventing coal-gas outburst. Several effect factors to effect of deep-hole presplitting explosion, such as rigidity of coal and buried height as well as diameter of explosive holes and couple coefficient of explosion and distance between explosive holes and control holes in the same rigidity of coal and buried height and explosion intensity condition, are acquired, and several new results are acquired as followings:(1) The propagation rules of stress wave by explosion in viscous-elastic media is acquired:①explosion generated stress waves attenuate as spreading distance;②when spreading distance is less than 10m, stress waves’ attenuation becomes minishing as the augment of delay time, and after spreading distance is larger than 10m, stress waves’ attenuation becomes augment as the augment of delay time;(2) Rigidity of coal have big effect on explosion result: less rigidity of coal, easier to be destroyed. Under explosion generated stress waves, coal around explosive holes are very easy to crush. And crush circle zone is form, which has cushioning effect, and stops further growth of cracks. So bigger rigidity of coal, more abundant the cracks grow;(3) Under the same explosion intensity, buried height of coal has little effect to the result of deep-hole presplitting explosion. So this technology of deep-hole presplitting explosion can also be used in deep-buried coal bed;(4) After analysis, diameter of explosive holes’ effect to result of deep-hole presplitting explosion is acquired. As the augment of diameter of explosive holes, the peak value of supporting stress in coal around explosive holes become high, and distance of peak value becomes large, but that fluctuates within a narrow range. So, when diameter of explosive holes become large, stress relief radius also becomes large, and stress relief radius R_a fluctuates between 2.7 and 3.5m.(5) Powder charge couple coefficient’s effect to result of explosive is acquired: when couple coefficient B_l =0.6, ground stress curve has maximum and minimum value, and stress concentration form around explosive holes, so stress relief effect is very little; when couple coefficient B_l is between 0.8 and 1.0, long perfoliate cracks are generated. So ground peak value and stress relief distance is large, and stress relief result is good. So powder charge couple coefficient has great effect to ground stress relief, and larger couple coefficient, better stress relief;(6) Reasonable distance between explosive holes and control holes is increased: when distance L between explosive holes and control holes is in the range of 3～4m, stress relief radius becomes large as the augment of L, and relief result of ground stress become good;From experiment effect of on-field experiment, permeability of coal bed is remarkably increased by deep-hole presplitting explosion, and drainage gas concentration and volume of gas flow is remarkably increased, and effective relief radius is 3～3.5m. And this shows that the technology of deep-hole presplitting explosion is a kind of feasible method to increase permeability of low permeability and high gas coal bed, and this technology provides dependable technology safeguard to effectively and intensively mine coal for low permeability and high gas coal bed.更多还原