底板穿层钻孔爆破煤层增透裂隙分布规律研究与应用

发布时间：2018-01-29 22:24

本文关键词： 穿层钻孔松软低透煤煤岩交界处裂隙分布爆破增透　出处：《安徽理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：本文基于瓦斯流动理论、瓦斯抽采技术和深孔预裂爆破增透理论,针对松软低透气性煤体在煤体中打钻孔容易垮孔、成孔率低,使得装药困难、封孔困难问题以及煤层装药爆破后松软煤体产生裂隙很快闭合,很难达到长效增透的问题,提出了底板穿层钻孔煤岩层交界处装药爆破的增透方法,通过理论分析、搭建系统进行相似模拟试验、数值模拟和现场试验的研究方法路线进行了不同控制孔孔径条件下的爆破增透尝试研究,取得了以下结论与成果:(1)在煤岩交界处装药爆破产生的能量使煤岩体产生了丰富的裂隙,一方面增强了煤层瓦斯渗透性的同时保护了用于后期抽采瓦斯的底板岩层中的控制孔,另一方面底板岩层中的裂隙为松软的煤层中的裂隙和位移提供了空间,有效减少裂隙的闭合,并提供了稳定的瓦斯流通通道。(2)随着控制孔径的增大,对裂隙的导向作用越明显,爆破空腔越小,贯穿到模型边界的裂隙偏转角度越来越小,孔径增大到一定程度后降低了相对应力集中度,使得裂隙呈现明显的网状分布。(3)在控制孔较大的情况,由于提供了足够的自由面,在爆破能量的作用下,煤体产生了以爆破孔为中心向四周挤压变形移动为主,以微裂隙为辅的的破坏,使得煤体有个从模型四周凹向中心的8°的角度。(4)通过在煤岩体交界处装药爆破,应力波在传播到煤岩层交界弱面,形成多次的反射叠加,这种反复的拉伸叠加作用在煤体,使得煤体产生更多的位移和破坏。(5)通过数值模拟计算结果得出:随着控制孔的不断增大,煤岩体中的裂隙发育越来越丰富,煤岩体的位移和相互侵入程度越大,损耗在爆破空腔里的能量越少,空腔越小;当控制孔径达到一定程度继续增大时,由于控制孔提供很大的自由面,使得煤体在爆破作用下产生了较为明显的片区移动并在控制孔附近产生破坏,与产生的裂隙的双重作用下极大的增加了煤体的透气性,同时岩体中的裂隙与煤体中的裂隙形成立体裂隙结构,岩体中稳定的控制孔为后续的瓦斯抽采作业提供了长期高效的保障。(6)工业试验采用了底板穿层钻孔煤岩交界处装药爆破方案增加了瓦斯抽采浓度和纯流量,增加了瓦斯渗透性,有效增透半径达到6m,消除了石门揭煤的瓦斯突出危险。
[Abstract]:Based on gas flow theory, gas extraction technology and deep-hole pre-splitting blasting antireflection theory, aiming at soft and low permeability coal body drilling in coal easily collapse hole, low porosity, which makes charging difficult. The difficult problem of sealing holes and the problem of quick closure of cracks produced by soft coal body after explosive blasting in coal seam are very difficult to achieve the problem of long effect antireflection. The antireflection method of charge blasting at the junction of coal and rock strata with boreholes in bottom slab perforating layer is put forward. Through theoretical analysis, the similar simulation test, numerical simulation and field test were carried out to study the blasting antireflection under different control hole aperture conditions. The following conclusions and results are obtained: (1) the energy produced by explosive blasting at the junction of coal and rock makes the coal and rock mass produce abundant fractures. On the one hand, it enhances the permeability of coal seam gas and protects the control hole in the floor rock layer used in the later stage of gas drainage. On the other hand, the crack in the floor rock layer provides space for the crack and displacement in the soft coal seam. Effectively reduce the closure of fractures, and provide a stable gas flow channel. 2) with the increase of the control aperture, the more obvious the guiding effect on the fracture, the smaller the blasting cavity. The angle of fracture deflection through the boundary of the model becomes smaller and smaller, and the aperture increases to a certain extent, which reduces the concentration of the corresponding force, which makes the fracture appear obvious net distribution. As a result of providing enough free surface, under the action of blasting energy, the coal body produces the destruction that the center of the blasting hole is squeezing and deformation moving around, supplemented by the micro-crack. The coal body has an angle of 8 掳from the concave to the center around the model. By blasting at the junction of coal and rock mass, the stress wave propagates to the weak surface of the coal strata and forms multiple reflection superposition. This repeated stretching superposition action on the coal body, so that the coal produced more displacement and damage. 5) through the numerical simulation results: with the increase of the control hole. The development of fractures in coal and rock mass is more and more abundant, the greater the displacement and mutual invasion of coal and rock mass, the less energy in the blasting cavity and the smaller the cavity. When the control aperture increases to a certain extent, because the control hole provides a large free surface, the coal body moves obviously under the action of blasting and causes damage near the control hole. The gas permeability of coal body is greatly increased under the action of double action and the crack in the rock mass and the crack in the coal body form the three-dimensional fissure structure at the same time. The stable control hole in the rock mass provides a long-term and efficient guarantee for the subsequent gas drainage operation. In the industrial test, the charge blasting scheme at the junction of coal and rock is used to increase the concentration of gas extraction and the pure flow rate. The gas permeability is increased and the effective antireflection radius reaches 6 m.The danger of gas outburst in Shimen coal is eliminated.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD712.61

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