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1.
近距离上保护层开采瓦斯运移规律数值分析 总被引：10，自引：1，他引：9
采动裂隙是瓦斯运移的通道,搞清瓦斯运移规律是瓦斯治理的前提。在考虑岩石动态破坏过程和含瓦斯煤岩渗流-应力-损伤耦合的基础上,结合平煤五矿实际地质条件和开采工艺,建立了数值计算模型,应用RFPA-Gas程序模拟了近距离上保护层采动顶底板岩层变形破坏、裂隙演化规律与瓦斯运移规律。模拟结果较好地再现了保护层开采过程中煤岩层应力变化、顶底板损伤及裂隙演化过程,得到了上覆岩层移动的“上三带”（冒落带、裂隙带和弯曲下沉带）和底板变形的“下两带”（底板变形破坏带和弹塑性变形带）。得到了被保护层瓦斯流量分布、瓦斯压力分布和透气系数的变化规律,卸压煤层瓦斯透气性增大了2 500倍,得到了煤壁下方压缩区和膨胀区之间的张剪瓦斯渗流通道,并将保护层底板压缩区和膨胀区的瓦斯渗流特征提炼出来：压缩区对应的是渗流减速减量区、膨胀区由卸压膨胀陡变区和卸压膨胀平稳区组成,分别对应着渗流急剧增速增量区和渗流平稳增量区。指出卸压膨胀陡变区是瓦斯突出危险区,为近距离保护层开采瓦斯治理指明了方向。实践表明,瓦斯治理效果显著。 相似文献
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The fractured zones caused by mining were studied in the overburden of the Torezko-Snezhnyanskaya area, Ukraine, through the change in natural gas emission from these zones during longwall coal excavation. Zones of interconnected fractures and separate horizontal fractures were studied with vertical wells drilled from the ground surface down to active underground workings. The maximum heights of the zone of interconnected fractures and separate horizontal fractures may reach 19–41 and 53–92 times the thickness of the coal seam respectively. It was found that the ratio between the maximum height of the zone of interconnected fractures and the thickness of the extracted coal seam increases with the increasing number of rock layer interfaces and decreases with the increasing stiffness of immediate roof. It is shown that the growth of the zone of interconnected fractures occurred during 17–39 days at an average rate of 0.94–1.97 m day?1 and it was accompanied by increasing methane emission from overburden. Observation shows that the formation of separate horizontal fractures began only 11–49.5 days after the height of the zone of interconnected fractures reached its maximum value. Formation of separate horizontal fractures in overburden over the longwall excavation occurred as a stepped process from lower to upper sandstone–sandy shale layer interfaces in the direction of the ground surface. 相似文献
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Evolution and effect of the stress concentration and rock failure in the deep multi-seam coal mining 总被引：1，自引：0，他引：1
Mingwei Zhang Hideki Shimada Takashi Sasaoka Kikuo Matsui Linming Dou 《Environmental Earth Sciences》2014,72(3):629-643
Supports crushing accident occasionally occurs in the protected seam exploitation of deep multi-seam coal mining structure and results in adverse effect to the production. To prevent its recurrence in a newly developed working field, a 3D numerical extraction model was built based on the geologic and mining conditions of Jining coal mine to evolve the changes, state and characteristics of the reconstructed vertical and lateral stress in rock interlayer after protective seam exploitation. Stress release and increase zones of this mining structure were separated. Mining-induced localized stress concentration and the interlayer rock failure behavior were explored. The action of concentrated stress on the hydraulic supports in protected seam was discussed upon the major stress redistribution. Using the infinitesimal strain method, a mechanical model was created to further explore, from the vertical and lateral directions, the cause and mechanism of localized stress concentration and rock failure behavior in rock interlayer. The field investigation was finally performed to verify the numerical and mechanical results, and the essential control measures were proposed to prevent this accident. Key findings of this study bring some new insights into the deep multi-seam coal extraction and help to promote a more reliable underground mining. 相似文献
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铁法矿区煤储层裂隙系统评价与渗透率预测研究 总被引：5，自引：0，他引：5
通过对铁法矿区矿井实际资料的研究,依据围岩节理及煤层裂隙的宏观、微观统计分析,探讨了煤储层孔裂隙的发育特征,对该区储层渗透率进行了预测.认为区内褶曲发育,褶皱轴部地带为裂隙发育带,煤层裂隙发育,连通性好,具备储层渗透性好的优势;受区域构造应力场控制,裂隙发育表现出明显的方向性,主裂隙发育的NW方向为渗透性优势方位. 相似文献
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Shaoping Zhou Kan Wu Dawei Zhou Liang Li Yuankun Xu 《Geotechnical and Geological Engineering》2016,34(6):1847-1856
To study the displacement caused by underground mining, the displacement field in the strata overlying the mine was simulated in nine similar-material models with coal seam dip angles of 0°–80°. Digital close-range photogrammetry was employed to observe the displacement in these models and produce displacement vector diagrams of observation points set on the model surfaces. The movement boundary of the rock mass was extracted and determined. According to the displacement vectors’ direction, the displacement field within the movement boundary was divided into five zones: two zones with displacement vectors pointing towards the goaf center, two zones with vectors pointing towards the coal pillar, and one zone with displacement vectors pointing vertically downward. A symmetry index was defined to analyze the symmetry of the displacement field, and the results show that as the coal seam dip angle increased from 0° to 80°, the displacement field in the strata changed according to the following pattern: symmetric → asymmetric → nearly symmetric, with a transition angle of about 45°. The percentage of the area of the above-defined five zones relative to the displacement field’s total area also changed, showing a regular pattern. This study also revealed that the movement boundary inside the overlaying rock layers is not a straight line, but an S-shaped curve. These findings can enhance our understanding of the internal mechanism of ground subsidence and contribute to more effective prediction of the deformation occurring inside a given rock mass. 相似文献
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Al-Amri Abdullah M. Abdelrahman Kamal Mellors Robert Harris David 《Arabian Journal of Geosciences》2020,13(8):1-11
Influenced by mining activities in adjacent coal seams, stresses on rocks surrounding roadway were redistributed, and the roadways in lower coal seam were subjected to the asymmetrical roof falling and roof sagging. Considering stresses effect on the plastic zone around the roadway, numerical models were carried out by FLAC to investigate plastic zone with respect to stress ratio and direction of stresses. The relationship between the properties of surrounding rock and plastic zone boundary was also investigated by another numerical model and analytical study, whereby the tailgate stability of panel 30,501 in Tashan coal mine was implemented. It is shown that the rocks surrounding a roadway in the lower coal seam were subjected to unequal stresses, and the principal stress direction was deflected from the original direction. High stresses and big stress ratio can produce butterfly-shaped or X-shaped plastic zone. The direction of stresses was deflected, causing the plastic zone around the roadway to be transferred from the shoulder to the roof of the roadway. Consequently, asymmetrical stresses produce asymmetrical plastic zone. On this basis, the tailgate should be assigned conditions of the stresses and stress ratio at a low level. In this way, the tailgate was arranged at the position where the horizontal distance from the roadway in the lower seam to the centre line of the coal pillar in the upper seam (x) is 52.5 m, and was stable relatively. 相似文献
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煤层底板变形破坏除受地质因素控制外,还受开采因素影响。通过试验和理论分析,系统研究了煤炭开采对回采工作面底板应力、应变和破坏及渗透性的影响。研究结果表明,不同岩性岩石的渗透性在全应力-应变过程中为应变的函数,在微裂隙闭合和弹性变形阶段,岩石的原生孔隙和裂隙容易被压密,岩石的渗透率随应力的增加由大变小明显,当应力增大至极限强度时岩石试件破坏形成贯穿裂隙,岩石的渗透率迅速增大至最大,不同岩性岩石存在一定差异性;随着回采工作面推进,煤层底板岩层在横向上划分为原岩应力区、超前压力压缩区、采动矿压直接破坏区和底板岩体应力恢复区4个区。煤层底板岩体的渗透性随着煤炭开采底板岩体变形破坏而呈规律性变化。 相似文献
8.
Localization of mining-induced horizontal fractures along rock layer interfaces in overburden: field measurements and prediction 总被引：3，自引：0，他引：3
V. Palchik 《Environmental Geology》2005,48(1):68-80
The locations of mining-induced horizontal fractures along rock interfaces in the overburden of Donetsk Coal Basin were identified using an original experimental device. The device traps methane from horizontal fracture zone (100–fold coal seam thickness) over an active longwall mining excavation. Presence or absence of horizontal fractures along rock layer interfaces is correlated with physical characteristics of the overburden, such as thickness, uniaxial compressive strength of overburden rock layers, location of rock layer interfaces and thickness of extracted coal seams. As a result, a combined criterion based on these physical characteristics is proposed to predict the presence of overburden horizontal fracturing in coal mine operations. 相似文献
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宁夏石嘴山矿区位于西部黄河流域,其煤矿采空区沉陷导致地表生态和环境问题频发,对其采煤沉陷分析将对西部黄河流域煤矿区的环境修复有一定的积极作用。为研究缓倾斜煤层采空区围岩应力与位移场演化特征,以宁夏石嘴山矿区为对象,基于FLAC3D数值模拟软件,建立缓斜煤层开采三维数值模型,计算分析采空区围岩应力、塑性区及位移变化规律,并基于两时相DEM叠加统计分析地表位移变化,与数值模拟结果进行相互验证。结果表明:地下开采引起应力重分布,采空区顶板及煤柱出现明显的应力集中现象,最大主应力呈现从煤层顶板向地表递减的变化趋势;越靠近采空区顶部的岩层垂直位移越大,随着远离采空区逐渐减少,开采完成后地表垂直位移最大值约12 m;随着采空区面积的不断增大,采空区四周及角隅处塑性区逐步延伸扩大,且以剪切破坏为主;地面沉陷盆地不对称,2个沉降中心均发生在沉陷盆地中部且偏下山方向,下山方向比上山方向影响范围更大;数值模拟计算的沉降量与两时相DEM叠加统计分析的变化量结果及趋势基本一致,研究成果可为煤炭安全开采提供参考依据,为地表沉降监测提供新方法。 相似文献
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地应力是影响煤层气开发的关键参数,为了分析太原西山区块煤储层地应力条件,为煤层气勘探开发提供理论依据,采用水力压裂法测量地应力,统计了太原西山区块35口井煤储层地应力资料,获取二叠系山西组2号煤储层地应力与煤层埋深之间的相关关系,阐明了现今地应力分布特征。结果表明,研究区山西组2号煤层破裂压力梯度、闭合压力梯度和煤储层压力梯度的平均值分别为4.77 MPa/hm、2.82 MPa/hm和0.6 MPa/hm;2号煤层最小水平主应力梯度、最大水平主应力梯度和垂直主应力梯度的平均值分别为2.82 MPa/hm、3.24 MPa/hm和2.7 MPa/hm。主应力均随煤层埋深增加呈线性规律增高。根据最小水平主应力的大小,将研究区划分为低应力区、中应力区、高应力区3个区。 相似文献
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为了查明河南省不同构造区内二1煤层中气体的流动特征和煤体受构造变形分异后的独特性,采用实验数据分析、瓦斯地质和渗流学理论,研究煤中孔容分布、孔径受应力影响后的变化以及煤体强度受构造应力作用下的变形和破坏特点。结果表明,煤层中甲烷连续流型占优的排序为:太行构造区、崤熊构造区、嵩萁构造区。煤中甲烷流型差异受区域构造变形体制控制,太行构造区的拉伸变形导致煤体强度值域分布广,最大体应变大于其他区域;嵩萁构造区的重力滑动、剪切和伸展变形使煤体强度和孔隙率最低、最大体应变最小;崤熊构造区内煤体的最大体应变介于两者之间。该结论对河南省煤层气开发有指导意义。 相似文献
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应用JHCF智能岩心流动测试仪,对鸡西盆地梨树镇坳陷的煤层,分别进行了恒定温度不同有效应力、以及恒定有效应力不同温度的渗透率敏感性试验,通过对试验所得数据整理分析,获得了煤层渗透率随温度和有效应力的变化规律,煤层渗透率随有效应力的增大呈指数式下降,而随温度的变化不明显,因此建立了煤层渗透率与地应力场和温度场关系的数学物理方程。利用数值分析方法,基于前人关于梨树镇坳陷的地质构造及应力场演化的研究,构建了区域煤层气储层的三维地质模型,计算了区域地应力场和温度场,结合煤层渗透率与地应力场、地温场关系数学物理方程,反演了区域渗透率的展布特征,为鸡西煤层气有利区选择提供了指导。 相似文献
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Coal and gas outburst disasters in coal seams are becoming more serious as coal mines extend deeper underground in China. Furthermore, the protective coal seam mining technology featured by economic efficiency has been proven to be the most effective and widely applied method for the prevention of coal and gas outburst disasters. However, the determinations of the protective area coal and gas outburst prevention in a pressure-relief boundary area are fundamental issues that research should be focused on. The technical method for determining stress distribution in pressure-relief boundary area during protective coal seam mining is put forward in this paper. The method is based on a stress-seepage coupled relationship within a gas-containing coal seam. The method includes complex lab experiments and on-site measurements at the Qingdong Coal Mine. The final data illustrate that the permeability and vertical stress in the pressure-relief boundary area of the coal sample form a negative exponential function relationship. Additionally, the permeability of the coal sample within the abovementioned area is significantly different compared with that located at the center of the pressure-relief area. In the pressure-relief boundary area, the gas pressure distribution gradient is 0.0375 MPa/m, while the vertical stress distribution gradient registers 0.56 MPa/m. Under this condition, coal and gas outburst disasters are prone to be triggered. Therefore, effective precautions against coal and gas outburst disasters can be put forward in accordance with stress distribution characteristics within the abovementioned “boundary area.” 相似文献
16.
断层对顶板稳定性影响相似模拟试验研究 总被引：13，自引：1，他引：12
通过相似模拟试验方法分析了不同倾向高角度正断层, 在采动影响下顶板岩体变形破坏和矿压分布规律。结果表明, 在采动影响下断层“活化”,断层带及其影响范围内的岩体破碎, 表现为周期断裂步距小, 冒落带高, 尤其是断层下盘, 顶板稳定性差; 当工作面开采到离断层面22.5~ 30 m时, 直到断层位置的前方煤体中支承压力增大, 煤体被压碎, 且随着距断层面距离的缩小, 支承压力的峰值位置向工作面前方转移; 通过断层后, 顶板岩体中支承压力减小, 比无断层存在的情况要低。 相似文献
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古构造应力场数值模拟及危险性预测研究 总被引：1，自引：0，他引：1
在精确确定构造序列与构造格架的基础上,探索出一套从建立构造模型、确定边界条件、选取岩体力学参数与危险性判断准则、计算古构造应力值、预测危险区与安全岛的基本思路与方法。采用有限元法,建立了矿区平面应力与三维构造模型,从加载方式和加载大小两方面模拟历史时期作用于成庄煤矿上的古构造应力。根据地表岩体和深部煤层中的节理,计算其内摩擦角和岩体抵抗变形破坏的能力,获得了古构造应力作用下地表表层、3#煤层的临界区、危险区与安全区。结合研究区节理、断层、褶皱、陷落柱等构造形迹特征,对危险性分区进行综合预测。预测结果揭示,山西晋城成庄煤矿区存在先南北向、后东西向的两期大的古构造运动,即先东西向加载60 MPa,再南北向加载110～180 MPa,可能的危险区分东、西两带,该结论对煤层岩体应力集中带和瓦斯突出区的预测具有重要的意义。 相似文献
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The sensitivity of coal permeability to the effective stress means that changes in stress as well as pore pressure within a coal seam lead to changes in permeability. In addition coal swells with gas adsorption and shrinks with desorption; these sorption strains impact on the coal stress state and thus the permeability. Therefore the consideration of gas migration in coal requires an appreciation of the coupled geomechanical behaviour. A number of approaches to representing coal permeability incorporate the geomechanical response and have found widespread use in reservoir simulation. However these approaches are based on two simplifying assumptions; uniaxial strain (i.e. zero strain in the horizontal plane) and constant vertical stress. This paper investigates the accuracy of these assumptions for reservoir simulation of enhanced coalbed methane through CO2 sequestration. A coupled simulation approach is used where the coalbed methane simulator SIMED II is coupled with the geomechanical model FLAC3D. This model is applied to three simulation case studies assembled from information presented in the literature. Two of these are for 100% CO2 injection, while the final example is where a flue gas (12.5% CO2 and 87.5% N2) is injected. It was found that the horizontal contrast in sorption strain within the coal seam caused by spatial differences in the total gas content leads to vertical stress variation. Thus the permeability calculated from the coupled simulation and that using an existing coal permeability model, the Shi–Durucan model, are significantly different; for the region in the vicinity of the production well the coupled permeability is greater than the Shi–Durucan model. In the vicinity of the injection well the permeability is less than that calculated using the Shi–Durucan model. This response is a function of the magnitude of the strain contrast within the seam and dissipates as these contrasts diminish. 相似文献
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霍县矿区石炭二叠纪含煤岩系沉积环境探讨 总被引：2，自引：0，他引：2
本文阐述了霍县矿区石炭二叠纪含煤岩系的岩矿、构造、砂岩粒度分布、微量元素、测井曲线、砂体与煤层形态等特征,据此作了沉积环境分析。本溪组主要为泻湖-潮坪沉积,太原组属下三角洲沉积为主,山西组以上三角洲沉积为主。煤层与下伏砂体的较厚带的空间分布有迭置与错位两类关系。这种关系不但对煤田的普查与勘探能起指导作用,还是一种鉴定沉积环境的新标志。 相似文献