【作者】 平琦；

【导师】 马芹永；

【作者基本信息】 安徽理工大学 ， 采矿工程， 2013， 博士

【摘要】 煤炭是我国的主体能源,随着需求量增加和开采强度不断加大,浅部资源逐渐减少和枯竭,煤矿进入深部开采将是必然趋势。深部岩体处于“三高”的复杂力学环境,采掘扰动时所表现出的力学响应特征与浅部岩体明显不同。随着煤矿开拓向深部延深,安全隐患随之增加,特别是近年来进入深部开采后的恶性事故屡屡发生,对深部资源的安全高效开采造成了巨大的威胁。因此,要保证我国煤炭后备能源供给,开展煤矿深部开采基础理论研究迫在眉睫。本文以两淮矿区深部开采为工程背景,确定煤矿巷道开挖工程中最常见的砂岩为试验研究对象。岩样分别采自祁东煤矿、卧龙湖煤矿和朱集西煤矿的-466m、-527m和-962m不同赋存深度。测试了3种岩样的基本物理性质,并进行电镜扫描(SEM)和X射线衍射(XRD)试验；利用RMT岩石力学试验系统进行静态力学试验,重点是利用直锥变截面分离式Hopkinson压杆(SHPB)试验装置对岩石进行动态力学试验研究。主要研究内容和成果如下：(1)设计加工了一种用于短圆柱体岩石试件的打磨夹具,以保证试件端面不平行度和轴向偏差满足试验要求。利用RMT岩石力学实验系统进行了静态条件下岩石的劈裂拉伸试验和单轴压缩试验等,分析了岩石试件的破坏形态和应力-应变曲线特征。(2)分析了一维弹性应力波在SHPB试验中传播过程,将传统的矩形波、梯形波和坡形波等加载波形,统一表达为具有不同前沿升时的梯形波,推导出具有任意前沿升时的梯形波入射加载情况下,试件内沿加载方向应力分布的相关计算公式,讨论分析了试件动态应力平衡时间和应力均匀性的影响因素和相关规律。(3)研究了煤矿砂岩在冲击载荷作用下单轴压缩力学性能,计算分析了不同种类岩石试件在光滑的试验入射波和其升时相同的理论梯形入射波加载情况下试件应力平衡时间和应力均匀性。发现采用变截面入射杆进行加载,能够实现岩石试件在应力峰值之前达到应力平衡,满足应力均匀性假定要求。(4)研究了高应变率下煤矿砂岩的动态拉伸性能,采取调整冲击气压的方法实现不同加载速率,以实施不同加载速率的动态劈裂拉伸试验,分别采用0.3,0.6,0.9,1.2MPa等4种冲击气压对岩石试件沿径向进行加载,测试了岩石试件的动态拉伸应力和应变率。分析了试验实测波形和应变率效应,得出高应变率下煤矿砂岩试件抗拉强度和应变率特性。(5)研究了岩石试件SHPB试验过程中的能量构成和耗散特征,尝试从能量角度出发,对岩石试件动态破坏形态、应变率效应和动态拉伸应力进行能耗分析。发现岩石试件的吸收能量绝大部分耗散于损伤演化和变形破坏,可以较好地反映岩石试件在冲击载荷作用下抗拉性能变化。(6)进行了岩石碎块筛分试验,筛孔尺寸拟选择0、0.15、0.3、0.6、1.18、2.36、4.75、9.5、13.2、16、19、26.5、31.5、37mm共14个等级。对冲击荷载作用下岩石试件的破碎块度和能量分析,建立岩石破碎块度和试件吸收能量之间的关系。根据岩石破碎的自相似性,运用分形理论对岩石破碎块度的分形特征进行研究。(7)结合煤矿不同赋存深度硬岩巷道特性,采用中深孔不同阶微差掏槽爆破和光面爆破试验,优化爆破参数设计。通过现场试验和应用表明,炮眼利用率超过90%,平均单进提高20%以上,爆破效果较好。更多还原

【Abstract】 Coal is the main energy in China. As coal demand and mining intensity increasing, resources in shallow decrease gradually and will be exhaustion someday, then deep mining will be the inevitable trend in coalmine. For the complex "three highs" mechanical environment deep rock mass in, its mechanical responses for excavation disturbance are obviously different with shallow rock mass. When coalmine tends to deep, potential safety hazards increase which becomes a great threat to safe and efficient mining of deep resource, especially fatal accidents occurred in recent years when first entering deep mining. Thus, in order to ensure supply of reserve coal energy in China, it is extremely urgent to carry out basic theory research of deep mining in coalmine.Based on deep mining in Huainan and Huaibei coalmines, sandstone, the most common rock in coalmine roadway, was selected to research. Rock specimens were collected from different covered depths in various coalmines, e.g. Qidong coalmine(-466m), Wolonghu coalmine(-527m) and Zhujixi coalmine(-962m). Basic physical properties were investigated, and scanning electron microscope test (SEM) and X-ray diffraction (XRD) test were also conducted. RMT rock mechanics test system was also adopted to carry out static mechanical tests. The key issue is using variable cross-secion spilt Hopkinson pressure bar (SHPB) apparatus researching dynamic mechanical properitie. Main research contents and results are as follows:(1) Design and manufacture a fixture in grinding short cylinder rock specimens to ensure its parallelism and axial alignment tolerance. Splitting tensile test and uniaxial compression test were conducted by RMT rock mechanics test system to analyze failure modes and characteristics of stress-strain curve.(2) Propagation of elastic stress wave in split Hopkinson pressure bar (SHPB) test was analyzed. And Rectangular wave, trapezoidal wave, and sloping wave were expressed as trapezoidal wave with different rising times to derivate related calculation formulas for stress distribution along loading direction. Several factors affecting time for stress equilibrium and stress uniformity were studied.(3) Uniaxial compressive mechanical performance of coalmine sandstone under impact loads was studied, and time for stress equilibrium and stress uniformity for three kinds of sandstone were also investigated by smoothed test incident wave and theoretical trapezoidal wave with same rising time. Stress equilibrium could achieved before stress peak by variable cross-section incident bar which met conditions in assumption of stress uniformity.(4) Different loading rates were implemented by adjusting impact pressure to investigate the dynamic tensile performance of coalmine sandstone under high strain rate. Four impact pressure,0.3,0.6,0.9and1.2MPa, were loaded in radial direction. Both actual measured waves and strain rate effect were analyzed and tensile stress and strain rate of sandstone under high strain rate were obtained.(5) Energy composition and energy dissipation characteristics of sandstone in SHPB test were investigated. Failure modes, strain rate effect and dynamic tensile stress were analyzed from energy point. And it is found that energy absorbed by rock specimens almost dissipated in damage evolution and deformation failure, and tensile performance of sandstone under dynamic loads was also reflected.(6)14sizes of sieves,0,0.15,0.3,0.6,1.18,2.36,4.75,9.5,13.2,16,19,26.5,31.5and37mm were employed to conduct broken fragments test. Relationship between broken size and absorbed energy was established by broken fragments analyses and energy analyses. According to the self-similarity of broken rock, fractal characteristics of broken fragments were studied by fractal theory.(7) Combined with characteristics of hard rock in different depth coalmine roadway, parameters in blasting design were optimized by medium-length hole differential blasting in different orders and smooth blasting test. By filed test and engineering application, utilization rate of perforation was more than90%, and average footage per month is improved over20%. So the blasting effect is good.更多还原