卸围压条件下含瓦斯水合物煤体应力-应变特性试验研究  

Stress-strain characteristics of coal mine gas hydrate-coal mixture under confining pressure unloading

作　　者：张保勇 于洋 高霞 吴强 张强 ZHANG Baoyong;YU Yang;GAO Xia;WU Qiang;ZHANG Qiang(School of Safety Engineering,Heilongjiang University of Science & Technology,Harbin 150022,China;School of Architecture &Civil Engineering,Heilongjiang University of Science & Technology,Harbin 150022,China)

机构地区：[1]黑龙江科技大学安全工程学院,黑龙江哈尔滨150022 [2]黑龙江科技大学建筑工程学院,黑龙江哈尔滨150022

出　　处：《煤炭学报》2021年第S01期281-290,共10页Journal of China Coal Society

基　　金：国家自然科学基金资助项目(51974112,51674108);黑龙江省普通本科高等学校青年创新人才培养计划资助项目(UNPYSCT-2017140)。

摘　　要：随着开采强度和能源需求的增大,煤矿开采深度逐年递增,煤与瓦斯突出等动力灾害愈加频繁,强度也越来越大。瓦斯水合固化防突技术通过中高压注水和向水中添加有利于水合物形成的促进剂的方法,使煤层中大部分瓦斯气体转变为固态水合物,从而促使煤层赋存瓦斯气体压力降低,同时水合物的生成提高了煤体强度,理论上可减弱或消除煤与瓦斯突出危险性。瓦斯水合固化后突出煤体力学性质测定是瓦斯水合固化技术应用的关键问题之一。此外,大范围煤炭开采对采掘空间煤岩体形成反复扰动,加卸载条件对含瓦斯水合物煤体力学性质影响较大。鉴于此,笔者开展常规三轴、卸围压下含瓦斯水合物煤体应力-应变特性研究,为瓦斯水合技术在煤与瓦斯突出防治的应用提供一定的理论依据。首先,采用含瓦斯水合物煤体原位生成与力学性质测定一体化装置在3种围压(12,16,20 MPa)和2种饱和度(50%,80%)下开展了含瓦斯水合物煤体常规三轴试验,根据常规三轴试验得到的峰值强度确定卸围压起始轴向应力,之后开展相同条件下含瓦斯水合物煤体卸围压试验。结果表明,相同围压下,较高含水量煤样具有较大的饱和度;卸围压条件下含瓦斯水合物煤体应力-应变曲线与常规三轴条件下具有显著差异,常规三轴条件下应力-应变曲线呈应变硬化型,而卸围压开始后应力-应变曲线会经历一个应力平台阶段;卸围压条件下含瓦斯水合物煤体能承载的最大应力较低;应力平台时间随围压和饱和度的增加近似线性增大,并且围压和饱和度越小,应力平台持续时间越短,煤体越易发生破坏;建立了饱和度和围压对应力平台持续时间耦合影响的多元线性回归方程,并对方程进行了检验,取得了较高的拟合度;卸围压条件下煤样破坏形式以剪切破坏为主、伴随劈裂破坏;随着围压增大,煤样破坏更为Dynamic disasters such as coal and gas outburst have become more frequent and intense due to the increases in mining depth caused by the increases in mining intensity and energy demand.Coal mine gas prevention based on hydrate method is termed as coal mine gas hydrate formation using medium-high pressure injected water and promoters.When most coal mine gas is transformed to hydrate phase,the gas pressure in the coal seam decreases,and the coal strength increases.This can theoretically reduce the risk of coal and gas outburst.The measurement of mechanical properties of coal mine gas hydrate-coal mixture is one of key issues in the application of coal and gas outburst prevention technology based on the hydrate method.In addition,a large-scale coal mining causes a repeated disturbance to the coal and rock mass in the excavation space.Therefore,the mechanical properties of coal mine gas hydrate-coal mixture mainly depend on the loading-unloading condition.In view of the above,the mechanical properties of coal mine gas hydrate-coal mixture under conventional triaxial compression tests and confining pressure unloading tests were investigated to provide theoretical reference for coal mine gas hydrate method application in coal and gas outburst prevention.Firstly,a series of triaxial compression tests was conducted on coal mine gas hydrate-coal mixture samples under different confining pressures(12,16,20 MPa)and hydrate saturations(50%,80%),using the integrated device for in-situ hydrate formation in coal and mechanical properties measurement of coal sample.Then,a series of confining pressure unloading tests was conducted,with the initial axial stress of confining pressure unloading tests determined from conventional triaxial compression tests.The results show that hydrates have greater saturation with higher water content under the same confining pressure.The stress-strain curves of coal mine gas hydrate-coal mixture exhibit quite different profiles under different stress paths.Specifically,the curves show strain harden

关 键 词：煤与瓦斯突出 应力-应变特性 卸围压 含瓦斯水合物煤体 应力平台 

分 类 号：TD712[矿业工程—矿井通风与安全]