初采覆岩破坏性影响区的解析高度

以现场实测资料和实际的开采条件为依据，建立回采工作面覆岩破坏的力学模型，分析初次开采时顶板最大冒落高度与采高、采深、顶板岩层的力学性质、采空区大小及顶板岩层的碎胀性之间的关系，利用微分方程求出初采覆岩破坏性影响区高度的解析解。     

Stability of coal pillar in gob-side entry driving under unstable overlying strata and its coupling support control technique

Considering the situation that it is difficult to control the stability of narrow coal pillar in gob-side entry driving under unstable overlying strata, the finite difference numerical simulation method was adopted to analyze the inner stress distribution and its evolution regularity, as well as the deformation characteristics of narrow coal pillar in gob-side entry driving, in the whole process from entry driving of last working face to the present working face mining. A new method of narrow coal pillar control based on the triune coupling support technique (TCST), which includes that high-strength prestressed thread steel bolt is used to strain the coal on the goaf side, and that short bolt to control the integrity of global displacement zone in coal pillar on the entry side, and that long grouting cable to fix anchor point to constrain the bed separation between global displacement zone and fixed zone, is thereby generated and applied to the field production. The result indicates that after entry excavating along the gob under unstable overlying strata, the supporting structure left on the gob side of narrow coal pillar is basically invalid to maintain the coal-pillar stability, and the large deformation of the pillar on the gob side is evident. Except for the significant dynamic pressure appearing in the coal mining of last working face and overlying strata stabilizing process, the stress variation inside the coal pillar in other stages are rather steady, however, the stress expansion is obvious and the coal pillar continues to deform. Once the gob-side entry driving is completed, a global displacement zone on the entry side appears in the shallow part of the pillar, whereas, a relatively steady fixed zone staying almost still in gob-side entry driving and present working face mining is found in the deep part of the pillar. The application of TCST can not only avoid the failure of pillar supporting structure, but exert the supporting capacity of the bolting structure left in the pillar of last sublevel entry, thus to jointly maintain the stability of coal pillar.     

Mechanism of rock burst caused by fracture of key strata during irregular working face mining and its prevention methods

To study the occurrence mechanism of rock burst during mining the irregular working face, the study took irregular panel 7447 near fault tectonic as an engineering background. The spatial fracture characteristic of overlying strata was analyzed by Winkler elastic foundation beam theory. Furthermore, the influence law of panel width to suspended width and limit breaking span of key strata were also analyzed by thin plate theory. Through micro-seismic monitoring, theoretical analysis, numerical simulation and working resistance of support of field measurement, this study investigated the fracture characteristic of overlying strata and mechanism of rock burst in irregular working face. The results show that the fracture characteristic of overlying strata shows a spatial trapezoid structure, with the main roof being as an undersurface. The fracture form changes from vertical “O-X” type to transverse “O-X” type with the increase of trapezoidal height. From the narrow mining face to the wide mining face, the suspended width of key strata is greater than its limit breaking width, and a strong dynamic load is produced by the fracture of key strata. The numerical simulation and micro-seismic monitoring results show that the initial fracture position of key strata is close to tailgate 7447. Also there is a high static load caused by fault tectonic. The dynamic and static combined load induce rock burst. Accordingly, a cooperative control technology was proposed, which can weaken dynamic load by hard roof directional hydraulic fracture and enhance surrounding rock by supporting system.     

Characteristics of mining gas channel expansion in the remote overlying strata and its control of gas flow

The technology of pressure relief gas drainage is one of the most effective and economic for preventing gas emissions in underground mines. Based on current understanding of strata breakage and fracture development in overlying strata, the current study divides the overlying strata into the following three longitudinal zones in terms of the state of gas flow: a turbulent channel zone, a transitional circulation channel zone and a seepage channel zone. According to the key strata discrimination theory of controlling the overlying strata, the calculation method establishes that the step-type expansion of the mining gas channel corresponds to the advancing distance of working face, and this research also confirms the expanding rule that the mining gas channel in overlying strata follows the advancing distance of mining working face. Based on the geological conditions of Xinjing Coal Mine of Yangquan, this paper researches the expanding rule of mining gas channel as well as the control action of the channel acting on the pressure relief flow under the condition of the remote protective layer, and got the distance using inversion that the step-type expanding of mining gas channel is corresponding to the advancing distance of working face, which verifies the accuracy and feasibility of theoretical calculation method proposed in this study. The research provides the theoretical basis for choosing the technology of pressure relief gas drainage and designing the parameters of construction.     

不等长工作面覆岩破坏规律的数值模拟分析

针对不等长工作面煤层开采日渐增多的现状,采用数值模拟与理论分析相结合的方法,对采场覆岩的破坏特征及支承压力的分布状态进行系统研究,并相应模拟出工作面前方应力场与位移场的演化规律。结果表明：工作面自开切眼开始向前推移,推进到工作面“见方”期或斜长的整数倍位置时,顶板活动剧烈,覆岩空间结构发生新旧更替,形成了“0”型破断区;不等长工作面推进过程中岩层运移极不规则,推进距离在衔接面前后20～30m的范围内,应力波动较大,数值变化明显;回采期间支承压力对覆岩活动产生了重要影响,其大小约为水平应力的1．5～2倍;就采动过程中竖向位移的变化而言,巷帮移近量远大于顶底板变形量,故工程实践中应特别注意对巷帮及顶板的加固和维护。     

采空区上覆岩层移动破坏动态力学模型的应用

采用采动岩体动态力学模型,对采动引起的覆岩移动破坏的时空规律进行了研究,结合兴隆庄矿５３０６工作面的地质、开采条件,对采动引起的断裂带发育发展规律,岩体内部离层发生发展规律、地表下沉规律等问题进行了分析,并对观测结果作出了较以前的各种理论模型更为符合实际的解释,该模型可在实际工作中得到了很好地应用。     

多煤层采区岩层移动相似材料的模拟研究

通过对平顶山煤业集团公司八矿多煤层采区同采条件下,下部煤层开采对上部煤层开采影响的相似材料模拟试验结果的分析,得出了下组煤层开采时上覆岩层的移动及变形规律、有关岩层移动参数、上组煤层巷道变形预计方法及采动影响的时空关系．     

薄基岩条带开采工程地质力学模型试验研究

针对兖州太平矿区内赋存有薄基岩的地层条件，以工程地质力学模型试验为手段，研究了薄基岩条件下条带开采覆岩与地表移动变形及破坏的工程地质机理及其主控因素，揭示了薄基岩条带综放开采引起的上覆岩层的破坏过程、破坏形态、破坏范围及地表的移动变形规律，为工程实践提供了理论依据。     

多煤层采区岩层移动相似材料的模拟研究

通过对平顶山煤业集团公司八矿多煤层采区同采条件下,下部煤层开采对上部煤层开采影响的相似材料模拟试验结果的分析,得出了下组煤层开采时上覆岩层的移动及变形规律、有关岩层移动参数、上组煤层巷道变形预计方法及采动影响的时空关系     

Stability of roof structure and its control in steeply inclined coal seams

To improve the effectiveness of control of surrounding rock and the stability of supports on longwall topcoal caving faces in steeply inclined coal seams, the stability of the roof structure and hydraulic supports was studied with physical simulation and theoretical analysis. The results show that roof strata in the vicinity of the tail gate subside extensively with small cutting height, while roof subsidence near the main gate is relatively assuasive. With increase of the mining space, the caving angle of the roof strata above the main gate increases. The characteristics of the vertical and horizontal displacement of the roof strata demonstrate that caved blocks rotate around the lower hinged point of the roof structure, which may lead to sliding instability. Large dip angle of the coal seam makes sliding instability of the roof structure easier.A three-hinged arch can be easily formed above both the tail and main gates in steeply inclined coal seams. With the growth in the dip angle, subsidence of the arch foot formed above the main gate decreases significantly, which reduces the probability of the roof structure becoming unstable as a result of large deformation, while the potential of the roof structure's sliding instability above the tail gate increases dramatically.     

煤矿深井采场矿压显现及其控制特点

根据采场围岩控制原则、垮落带岩层的判别式、裂隙带老顶在触矸处的下沉量计算式和移动支承压力与采深的关系,分析了采深对采场矿压显现不同参数的影响,并通过实测加以验证根据岩性随采深的变化,讨论了深井采场可能出现的冒顶事故,并提出了相应的控制,认为采深对矿压显现的影响在采场支护方面不明显,而煤壁片帮将随采深增加而加剧。深部围岩逐渐变碎强度有所降低。深部采场应加强对垮睦顶事故的防治,把顶板护好。     

卧龙湖煤矿8101工作面采动覆岩破坏特征研究

煤矿开采过程中覆岩破坏容易引发工作面溃砂、突水事故,为了保证卧龙湖煤矿8101工作面安全开采,根据矿区覆岩工程地质特征及矿区岩层柱状图,建立了FLAC3D数值模拟模型.通过FLAC3D软件模拟,得到了工作面推进时的覆岩应力场及覆岩塑性区分布图,由此分析得出在开切眼和煤壁处覆岩主要为剪切破坏,采空区上部主要为拉伸破坏,得到煤层开采时覆岩最大主应力1.78MPa,最大导水裂隙带高度31m.     

急斜煤层分段放顶煤开采合理段高选择研究

为确定急斜煤层水平分段综放开采条件下工作面段高的合理取值,将开采后裸露顶板岩层简化为三边固支的矩形薄板,采用薄板破断理论对受横向和纵向载荷作用下的斜置矩形薄岩板进行力学分析.研究表明:岩板走向长度、倾斜长度、岩层倾角、覆岩载荷及泊松比是影响段高取值的5个主要因素.应以在工作面上方采空区煤矸体沿着顶煤采出后形成的槽形采空区域下移前岩板不发生沿根部折断为极限段高的选择标准.工作面合理段高取值分为3类:第Ⅰ类煤层倾角45°～55°,取值在29 m范围内;第Ⅱ类55°～75°,取值在51 m范围内;第Ⅲ类75°～90°,该范围内开采工艺及设备选择对合理段高取值的影响更为重要.     

Hydraulic support crushed mechanism for the shallow seam mining face under the roadway pillars of room mining goaf

While the fully-mechanized longwall mining technology was employed in a shallow seam under a room mining goaf and overlained by thin bedrock and thick loose sands, the roadway pillars in the abandoned room mining goaf were in a stress-concentrated state, which may cause abnormal roof weighting, violent ground pressure behaviours, even roof fall and hydraulic support crushed(HSC) accidents. In this case,longwall mining safety and efficiency were seriously challenged. Based on the HSC accidents occurred during the longwall mining of 3-1-2 seam, which locates under the intersection zone of roadway pillars in the room mining goaf of 3-1-1 seam, this paper employed ground rock mechanics to analyse the overlying strata structure movement rules and presented the main influence factors and determination methods for the hydraulic support working resistance. The FLAC3 D software was used to simulate the overlying strata stress and plastic zone distribution characteristics. Field observation was implemented to contrastively analyse the hydraulic support working resistance distribution rules under the roadway pillars in strike direction, normal room mining goaf, roadway pillars in dip direction and intersection zone of roadway pillars. The results indicate that the key strata break along with rotations and reactions of the coal pillars deliver a larger concentrated load to the hydraulic support under intersection zone of roadway pillars than other conditions. The ‘‘overburden strata-key strata-roadway pillars-immediate roof" integrated load has exceeded the yield load that leads to HSC accidents. Findings in HSC mechanism provide a reasonable basis for shallow seam mining, and have important significance for the implementation of safe and efficient mining.     

河北宁晋草厂盐矿覆岩稳定性分析与评价

针对冀中平原宁晋一带采空区极易导致地表过度沉降、塌陷,土地盐碱化等地质灾害及环境安全问题,依据矩形板理论和弹性圆板理论对草厂盐矿上覆盖层稳定性进行了分析,得出溶腔覆岩在矩形板梁理论和无孔弹性圆板理论下的临界水平应力为4.90×10~8 kN和6.89×10~8 kN,并分析了两种模型下草厂盐矿上覆盖层的稳定可靠性。     

煤层开采过程中上覆岩层裂隙演化规律研究

以淮南煤矿典型工作面为例,采用离散元数值软件UDEC(universal distinct element code)对工作面回采过程中上下煤岩体内应力场的变化及直接顶冒落过程进行了模拟,分析了上覆煤岩体裂隙产生、发展的形成过程,得到了上覆煤岩裂隙演化规律。研究结果表明,倾向方向工作面回采后,上覆煤岩体内产生冒落、裂隙带和离层带,在工作面内上角位置产生O型圈裂隙带,裂隙发育最大高度为45m。煤层走向回采方向得到了初期来压步距约50m,周期来压步距约20m,上覆煤岩体裂隙在采空区上方约呈45°角发展,并随工作面的前进由下向上、由后往前依次演变。该结果对于煤与瓦斯共采中瓦斯抽放钻孔方位的布置具有工程指导意义。     

Heavy rockbursts due to longwall mining near protective pillars:A case study

Rockburst represents a very dangerous phenomenon in deep underground mining in unfavourable conditions such as great depth, high horizontal stress, proximity of important tectonic structures, and unmined pillars. The case study describes a recorded heavy rockburst in the Czech part of the Upper Silesian Coal Basin, which occurred during longwall mining near the protective pillar. The artificial dividing of geological blocks and creation of mining protective pillars(shaft pillars, crosscut pillars etc.) is a dangerous task in light of rockbursts occurring mainly due to overstressing of remaining pillars. A simple model of this situation is presented. Natural and mining conditions are analysed and presented in detail as well as registered seismicity during longwall mining in the area. Recorded rockbursts in the area of interest are described and their causes discussed. Many rockbursts near protective pillars were recorded in this mining region. Methodical instructions for rockburst prevention in proximity of protective pillars as well as for gates driving were devised based on the evaluation of rockburst causes. The paper presents these principles for prevention.     

采场覆岩中复合关键层的形成条件与判别方法

在采场覆岩运动中起主要控制作用的岩层为关键层，而有时关键层是由2层或2层以上岩层形成的复合岩层所组成，我们称其为复合关键层．本文在深入揭示复合岩层形成机理的基础上，给出了形成复合岩层的力学条件与数学表达式，进而建立了采场覆岩中复合关键层的判别方法，并编写了复合关键层的判别程序．实例分析表明，复合关键层在岩层运动中是客观存在的，比同组岩层分开后的单一岩层的控制作用的线性叠加要大得多．本项研究是岩层控制的关键层理论研究的深入和发展，将有力促进岩层控制理论和技术的发展．     

Mining-induced movement properties and fissure time-space evolution law in overlying strata

Mining-induced fracture zone will be produced in the overlying strata after the coal was mined. In this article, the mining-induced deformation of overlying strata and the time-space evolution law of fissure were studied by the methods of physical simulation and field measurement. The results show that bed separation fissure and vertical fissure will appear in the overlying strata above mining face, which form the wedge-shaped fissure zone. The open degree of fissure depends on the size of uncoordinated deformation between neighbor layers, and the absolute strata sinking controls both the width of bed separation zone and the open degree of vertical breakage fissure. At last, the calculating formula was deducted based on theoretical analysis.     

Measurement of overburden failure zones in close-multiple coal seams mining

In the Kaiping Coal field, mining of five coal seams, located within 80 m in the Kailuan Group, #5, #7, #8,#9 and #12 coal seam, is difficult due to small interburden thickness, concentrated stress distributions,high coal seam metamorphism, and complex geological conditions. By using the ZTR12 geological penetration radar(GPR) survey combined with borehole observations, the overburden caving due to mining of the five coals seams was measured. The development characteristics of full-cover rock fractures after mining were obtained from the GPR scan, which provides a measurement basis for the control of rock strata in close multiple coal seam mining. For the first time, it was found that the overburden caving pattern shows a periodic triangular caved characteristic. Furthermore, it is proposed that an upright triangular collapsed pile masonry and an inverted triangular with larger fragments piled up alternately appear in the lower gob. The research results show that the roof structure formed in the gob area can support the key overlying strata, which is beneficial to ensure the integrity and stability of the upper coal seams in multiple-seam mining of close coal seams.