深部矿井低透突出煤层膨胀生裂增透机理及应用研究

The project is aimed at the difficulty of gas extraction from low-permeability coal seam in China deep mine and the technology of increasing the permeability coefficient of coal seam which is not yet mature, putting forward the gas drainage method increasing the permeability coefficient of low-permeability outburst coal seam by expanding and producing fissures in deep mine. The project research the features of coal seam stress field and fissure field under the action of static fragmentation agent, research the mechanism of expanding and producing fissures of outburst coal seam in the working face, analysis the growth law of the static cracking agent in the holes along the two free surface directions of the aperture and orifice, master the relationship between the producing fissures performance in the outburst seam, the dose parameters and the drilling parameters. Through the experiment for getting the proper static fragmentation agent, it produce enough inflation pressure to rupture the coal seam in the control area to promote the coal seams within the cracks generate, expansion and breakthrough,significantly improve coal seam permeability coefficient in the gas drainage face and reduce the gas flow attenuation coefficient in the hole, thus improving the gas drainage parameters of low permeability coal seam and levels. Finally, using numerical software to simulate the split process of the static rupture agent expansion, fracture distribution law and range, gas parameters variation. The research project will produce the gas drainage mechanism and new technology in deep mine in our country for the first time, it is very important to reduce gas disasters and accidents of coal mine, reducing the gas emissions caused by the "greenhouse effect" and promote the interdisciplinary business studies between mechanical, materials and physical chemistry.

本项目针对我国深部矿井低透气性煤层瓦斯抽采难且现有增加煤层透气性系数技术尚未成熟，提出了低透突出煤层膨胀生裂增透的瓦斯抽采方法。本项目通过分析静态破裂剂作用下煤体应力场和裂隙场特征，研究瓦斯抽采工作面突出煤层胀裂机理，分析增裂孔内静态破碎剂沿孔径和孔口两个自由面方向胀裂规律，掌握突出煤层静态破碎剂增透性能与药量参数和钻孔参数之间的相互关系。通过实验获取合适的静态破裂剂产生足够膨胀压力破裂控制范围内煤层，促使煤层内裂隙生成、扩展和贯通，大幅度提高瓦斯抽放工作面煤层透气性系数和降低钻孔瓦斯流量衰减系数，从而提升低透气性煤层瓦斯抽放参数和煤层可抽等级。最后应用数值软件模拟增裂孔内静态破裂剂膨胀生裂过程、裂隙分布规律、范围及瓦斯参数变化规律。本项目研究将在国内首次形成深部矿井瓦斯抽放机理和新技术，对于减少我国煤矿瓦斯事故、减少瓦斯温室效应及促进力学、材料、物理化学等学科交叉研究都具有重要意义。

随着贵州省煤矿往深部开采，低透突出煤层瓦斯抽采问题将更常见且更难。因此提高煤层透气性仍为贵州省煤矿实施有效瓦斯抽放的关键问题。本项目通过静态膨胀剂产生足够膨胀力开裂控制范围内的突出煤层，大幅提高煤矿采掘突出工作面煤层透气性系数和降低钻孔瓦斯流量衰减系数，从而提高低透突出煤层瓦斯抽采参数和可抽采等级。. 本项目主要采用了理论分析、实验研究、现场测试和数值模拟等研究方法。理论分析并通过建立模拟实验测试系统验证了静态膨胀剂作用下煤体经历了裂隙出现、裂隙传播和裂隙扩展贯通三个过程。实验分析了作业温度、钻孔直径、膨胀剂浓度等因素影响静态膨胀剂膨胀性能。煤矿井下作业环境下，四种类型静态膨胀剂产生的膨胀力均能达到30-50Mpa，理论研究了静态膨胀剂增透性能与药量参数和钻孔参数之间的相互关系。实验证明了通过合理布置自由面，静态膨胀剂能膨胀开裂突出煤层及其顶底板岩体，实验论证了静态膨胀剂增透突出煤层作用原理及可行性。. 通过现场测试金佳煤矿1235运输巷M3突出煤层被静态膨胀的开裂情况，观测到抽采钻孔内的煤体裂隙明显增多，3种不同孔径钻孔的瓦斯抽采流量及瓦斯抽采浓度都有明显提高。当钻孔孔径为94mm，膨胀孔与抽采钻孔孔间距为12~15倍时，煤层开裂效果最好。理论研究了膨胀孔内静态膨胀剂沿孔径和孔口两个自由面方向开裂规律。. 通过对比实测某煤矿151210运输巷和回风巷的瓦斯抽放效果，注入膨胀孔中的静态膨胀剂膨胀开裂了临近的瓦斯抽放孔，151210回风巷抽放孔内壁均有明显的膨胀开裂效果，新生的膨胀裂隙提高了151210回风巷的瓦斯抽放浓度。抽放同样突出煤层瓦斯量和残余瓦斯含量相等的情况下，回风巷所需抽放时间较运输巷减少了36天和缩短了26.3%。静态膨胀开裂增透技术提高了151210回风巷的瓦斯抽采效果。本项目形成了静态膨胀开裂突出煤层增透新方法，为贵州省及全国低透突出煤层瓦斯抽采提供了新技术。