浅埋薄基岩采煤工作面覆岩纵向贯通裂隙演化规律研究

发布时间：2018-01-05 20:17

本文关键词：浅埋薄基岩采煤工作面覆岩纵向贯通裂隙演化规律研究　出处：《中国矿业大学(北京)》2016年博士论文　论文类型：学位论文

【摘要】：我国西部地区蕴藏着十分丰富的煤炭资源,神东煤田是中国已探明的最大煤田,位于内蒙古自治区南部地区与陕西省西北部地区,煤田总面积达22860km2。该区域的煤炭资源为我国的国民经济发展做出了突出贡献,由于煤层赋存条件简单且厚度大等优势,为煤炭的机械化、高强度开采提供了得天独厚的条件,但在实际的开采中又由于煤层的埋深浅、基岩薄、上覆松散层厚度大,使得工作面在回采过程中上覆岩层产生的裂隙形成了沟通工作面与上覆松散层的裂隙,裂隙甚至能直达地表,若覆松散层富含潜水就会造成溃水溃砂灾害,对矿井的安全生产造成了极大的隐患。所以掌握神东矿区这种浅埋深、基岩薄的条件下产生的纵向裂隙演化规律,并采取相应的对策预防溃水溃砂灾害的发生对神东矿区矿井的安全高效绿色开采将具有重要意义。本文以昌汉沟矿为工程背景,掌握了开采煤层覆岩特征、煤岩物理力学性质、含煤岩系岩石学特征和原始沉积环境覆岩稳定性,通过相似模拟和数值模拟手段分析了浅埋薄基岩工作面纵向贯通裂隙演变规律,建立了上覆岩层力学模型,掌握了工作面纵向贯通裂隙的演化过程,并通过对纵向贯通裂隙的现场实测研究,最终提出了溃水溃砂的控制技术。本文主要结论如下:(1)掌握了昌汉沟矿4煤组覆岩结构特征与稳定性昌汉沟矿区4煤组沉积环境主要为河流中下游泛滥平原沉积环境;从昌汉沟矿围岩显微组分可以观测出,昌汉沟矿砂岩胶结类型为泥质胶结,固结成岩作用弱,导致岩石强度较低,同时由于粘土成分含量高,遇水会出现膨胀和崩解,会成分顶板稳定性带来不良影响;依据研究区内成煤环境内砂泥比不同取值范围,划分出Ⅰ~Ⅴ级五类沉积相岩层稳定性分区。昌汉沟矿4煤组煤Ⅰ~Ⅴ级分区均有分布,且以Ⅲ~Ⅴ级分区为主;计算出不同分区的沉积相岩层稳定性影响因素,Ⅰ级取1.00、Ⅱ级0.83、Ⅲ级0.65、Ⅳ级取0.60和Ⅴ级取0.58。此沉积相岩层稳定性系数可用于顶板岩层稳定性分类计算中,量化了各区原始沉积环境差异。(2)揭示了浅埋薄基岩工作面纵向贯通裂隙演变规律采用相似模拟分析,获取了工作面的纵向贯通裂隙演化过程初步得到裂隙的演化的四个阶段,分别为:(1)裂隙孕育阶段:在此阶段过程中,基本顶发生初次垮落,随着工作面继续向前开采,前方的一定区域内开始出现纵向裂隙,而且随着开采的进行,裂隙呈现逐渐扩展的状态,扩展的最终结果贯通工作面与载荷层,在此期间,开始出现第一次周期来压。(2)裂隙张开阶段:当发生第一次周期来压时,上覆基岩发生回转,回转过程以纵向贯通裂隙为轴线,向采空区方向回转,上覆基岩的回转使得本已存在的纵向裂隙逐渐张开,当覆岩回转至极限时,裂隙不再继续张大。(3)裂隙迅速闭合阶段:当工作面采高较大时,随着工作面的继续推进,第一次周期来压所形成的岩块在支架后方发生整体切落,覆岩反向回转,岩块垮落后的产生碎胀,而且跨落后裂隙结构面不平整,导致纵向贯通裂隙迅速闭合。(4)裂隙压实阶段:当第二次周期来压时,相邻覆岩发生回转运动,对已垮落岩块产生挤压作用力,使得已经闭合纵向贯通裂隙被进一步压实。采用数值模拟的方法进行浅埋薄基岩工作面上覆岩层的纵向贯通裂隙张开、闭合过程研究,进一步细致分析了采动影响下工作面纵向贯通裂隙动态发育现象,即张开闭合现象:基本顶在工作面推进过程中所形成的结构状态及其破断失稳决定了工作面纵向贯通裂隙的发育扩展过程。周期来压过程中,由于基本顶岩块的回转造成覆岩纵向裂隙尺寸不断增大,随着破断覆岩的整体切落与反向回转,出现纵向贯通裂隙的分离单元体之间又开始重新接触,由此可知纵向贯通裂隙已经闭合;当第二次周期来压时,相邻覆岩发生回转运动,对已垮落岩块产生挤压作用力,使得已经闭合纵向贯通裂隙被进一步压实。通过数值计算,工作面纵向贯通裂隙的整个动态发育状态与相似模拟结果基本相同。(3)从力学机制上阐述了工作面溃砂溃水原因针对神东煤炭集团昌汉沟煤矿这一典型浅埋薄基岩采煤工作面进行了纵向贯通裂隙演化过程力学分析,在浅埋薄基岩的条件下,由于工作面持续推进,靠后的周期来压会使前一次周期来压产生的关键岩块出现切落现象,此时关键岩块的前段角在受到向下的剪切力和水平力的共同作用,会形成近似的“台阶岩梁”结构,从而建立了浅埋博基岩采煤工作面纵向贯通裂隙演化过程的力学模型。由于工作面的持续推进造成顶板关键岩块的周期性破断,从而产生了浅埋薄基岩的顶板纵向贯通裂隙,其裂隙尺寸受实际地质条件影响巨大,与破断岩块间的块度、相互间的错位量和其所受的水平力大小、工作面采高、直接顶厚度等密切相关,当裂隙由于关键岩块的回转而扩展到一定的程度时,就会使主导周期来压产生的关键岩块发生切落,并使得上一周期来压产生的纵向贯通裂隙发生闭合,随后这次周期来压产生的纵向贯通裂隙经历张开扩展后又会由于下一个周期来压产生的纵向贯通裂隙而闭合,周而复始。(4)提出了工作面溃砂溃水的控制方法①合理安排工作面推进速度工作面的推进速度对覆岩移动特征和裂隙发育程度影响较明显。工作面推进速度越快相应的覆岩的下沉量越是平缓,所以其整体性就越强,相应的导水裂隙发育程度越小,对溃水溃砂的防治起一定的促进作用。一方面,快速推进的工作面使动态变形过程相应缩短,上覆岩层越近整体连续变形的压实效果越好。另一方面,工作面的快速推进使破断岩块间的裂隙发育时间短并且快速发生结构性闭合,从而阻止了导水通道的形成,也阻止了溃水溃砂的发生。破断岩块回转角的大小一般受基本顶周期来压步距的长短直接控制,即周期来压步距越小就会使回转角就越大,导致工作面纵向贯通裂隙发育程度也越高。一般情况下浅埋薄基岩工作面周期来压步距相对较小,纵向贯通裂隙不贯通的情况基本不存在,工作面推进速度一定得控制好。周期来压来临前,采用注浆等手段“堵”住纵向贯通裂隙,避免水砂通道的形成;来压之后,纵向贯通裂隙即刻开始发生结构性闭合,可不做处理。所以,工作面推进速度一定得控制好,尤其是在基岩周期来压来前,适当加快推进,避免间歇性停顿,以减小溃砂溃水事故隐患。②增大液压支架支撑力现场工作中要减小基岩切落前岩块的回转角度就必须保证液压支架工作阻力和作用面积,这样就会使得纵向贯通裂隙在产生小的尺寸后直接被快速切落,纵向贯通裂隙迅速闭合。同时,在裂隙闭合阶段进行再进行工作面暂停推进的检修、注浆等工序以便将安全隐患降到最低。此外,从工作面顶板和支架顶梁的几何关系看,应注重支架顶梁支撑力的发挥,加强支架顶梁的支撑力,弱化支架掩护梁的作用。尽量减小顶板暴露时间和面积,弱化薄基岩的顶板承载能力低的缺点。③富水区域限厚开采基岩破断块体的回转变形空间主要受采空区的充填程度影响,较大的懫空空间使得采空区充填程度较低,直接导致破断岩块回转角变大,进而,加大了工作面纵向贯通裂隙发育程度。因此,富水区域可适当降低采高,增加直接顶厚度相应的直接增加采后矸石在采空区的充填程度,以降低破断岩块回转角,限厚开采的同时也加快了工作面推进速度,有利于覆岩纵向贯通裂隙的快速闭合,减小溃砂溃水事故隐患。(5)形成了工作面溃水溃砂控制方法,并进行了工程实践对于浅埋薄基岩煤层而言,随着煤层的开采,其上覆岩层裂隙导通松散含水松散层,上部水体便会沿导水裂隙渗流。可靠的初撑阻力,保证工作面在断裂岩块下不至于产生较大的贯通裂缝;而推进速度的加快,可使破断岩块尽快与工作面一侧未断岩层在断面下端铰接并挤压发生结构性闭合,并在上覆垂直载荷作用下得到压实,从而有效控制了岩层的裂隙率、渗透性、导水性。据此在开采昌汉沟矿201工作面时,对工作不同区域的周期来压位置、来压位置附近是否出现溃砂溃水事故或溃水溃砂迹象进行了统计,统计结果表明,采用以合理安排工作面推进速度、增大液压支架支撑力为主的溃砂溃水综合防治方法,工作面推进期间,未出现溃水溃砂隐患,实现了矿井的安全、高效开采。
[Abstract]:The western region of China is rich in coal resources, Shendong coalfield is the largest coal Chinese proven, northwest of the southern region is located in the the Inner Mongolia Autonomous Region coalfield and Shaanxi Province, a total area of 22860km2. in the area of coal resources for the development of China's national economy has made outstanding contributions, the occurrence condition of coal seam thickness and simple the big advantages, for the mechanization of coal mining, high strength provides richly endowed by nature, but in the actual mining because the coal seam buried depth, thin bedrock and overlying loose layer thickness is large, the work surface strata in the mining process of the cracks formed communication working surface and the overlying loose layer crack, crack can even reach the ground, if the overburden layer is rich in water and sand burst diving will cause disaster to the safety production of mine caused great hidden danger. So the god east this area A shallow buried depth, longitudinal cracks and thin bedrock under the condition of evolution, and take corresponding measures to prevent collapse of water and sand disaster safe and efficient green mining of mine in Shendong mining area will have important significance. In this paper, Chang Han Gou mine as the engineering background, the characteristics of coal mining overburden rock physical mechanics. Coal properties, coal bearing strata and petrological characteristics of original sedimentary environment of overlying rock stability, through the simulation and numerical simulation analysis of the shallow buried thin bedrock surface longitudinal through cracks evolution, established overburden mechanics model, the evolution process of the master working face longitudinal through cracks, and through the field test research the longitudinal through cracks, finally put forward the control technology of water and sand burst. The main conclusions of this paper are as follows: (1) Master Chang Han Gou coal mine 4 group overburden structure characteristics and stability of Chang Han Gou mine 4 Coal Group The sedimentary environment is mainly in the middle and lower reaches of the river flood plain sedimentary environment; from Chang Han Gou rock macerals can be observed, Chang Han Gou mine sandstone cementation type is clay cementation, consolidation of weak diagenesis, the rock strength is low, and because the clay content is high, water will swell and collapse. It has negative effects on roof stability of components in the study area; on the basis of coal forming environment in different sand shale ratio range, Division I ~ V grade five types of sedimentary rock facies stability zoning. Chang Han Gou coal mine 4 Coal Group I ~ V grade partition were distributed, and III ~ V grade partition; calculate rock facies factors in different areas of stability, grade 1, grade 0.83, grade 0.65, grade 0.60 and grade V 0.58. of this sedimentary facies strata stability coefficient can be used for classification of roof strata stability calculation, quantitative appraisethe original sedimentary environment Difference. (2) revealed a shallow buried thin bedrock working surface longitudinal through cracks evolution with simulation analysis, four stages of working face were obtained through the longitudinal crack evolution process of the fracture evolution obtained were: (1) crack incubation stage: in this stage in the process of the basic roof first caving occurred with the face, to continue mining, began to appear a certain area in front of the longitudinal cracks, and with the exploitation of the fissure, gradually expanded state of the final results through the extended working surface and the load layer, in the meantime, begin the first periodic press. (2) fracture occurs when the first stage: the cycle pressure when the overlying bedrock occurs in the longitudinal rotary rotary process through cracks for the axis, to the goaf overlying bedrock of the direction of rotation, the rotary vertical cracks of the existing open gradually, when the rock back to The limit, no longer continue to crack big. (3) crack rapid closing stage: when the mining height is large, with the continued progress of working face, the rock first cycle pressure formed in the bracket behind the whole cutting, overburden rock fall reversal, have broken, and cross behind the fissure structural plane is not flat, causing longitudinal through cracks quickly closed. (4) the stage of crack compaction: when the second cycle pressure when the overburden occurs adjacent rotary motion, squeezing force to have caving rock, which has been closed through the longitudinal fissure. Further compaction of overlying strata in using numerical simulation method the shallow buried thin bedrock face vertical fracture, closed process research, further detailed analysis of the working face under the influence of vertical dynamic development of mining fissure phenomenon, namely open close phenomenon: the basic roof in the working face advancing Structure formed in the process of breaking and instability determines the working face through vertical fissure propagation process. The periodic weighting process, because the basic roof rock strata caused by rotary vertical fissure size increasing, with the overall breaking rock cut down and reverse turn, between the separation unit longitudinal through cracks began to contact the longitudinal through cracks have been closed; when the second cycle pressure when the overburden occurs adjacent rotary motion, squeezing force to have caving rock, which has been closed through further longitudinal cracks are compacted. Through numerical calculation, the dynamic development of working face the longitudinal through cracks and similar simulation results are basically the same. (3) from the mechanical mechanism described the working face water inrush of sand break reason for Shendong Coal Group Chang Han Gou coal mine is a typical shallow thin base Rock coal face are analyzed through vertical crack evolution mechanics in shallow buried thin bedrock under the condition, because of the continued advance of working face, the key rock block cycle by the pressure to make a periodic pressure resulting from the emergence of the cut phenomenon, at this time the key rock block front angle in the interaction by the downward shear force and horizontal force, will form an approximate "step beam" structure, which established the mechanical model of shallow bedrock mining work Bo longitudinal through cracks evolution. Due to the continued advance caused by periodic roof breaking key rock block, resulting in the roof of shallow thin bedrock the longitudinal through cracks, the crack size is affected by the actual geological condition is huge, and broken rock blocks between the block, offset each other and the horizontal force of the size of the mining height, the thickness of immediate roof closely related, when crack The key block of rotary gap and extended to a certain extent, it will make the key rock leading periodical pressure generated block cutting, and the longitudinal through cracks a closed cycle pressure generated by the vertical fracture experienced open expansion again because of the next cycle pressure generated the longitudinal through cracks and closed cycle, then the cycle pressure generated. (4) put forward the control method of working face water inrush of sand break the reasonable arrangement of the advancing speed of working face advancing speed of overburden movement characteristics and the degree of fracture effect is obvious. To promote the faster the corresponding rock face the subsidence is more gentle, so the greater degree of water flowing fractured development corresponding smaller, certain promotion on the prevention and control of water inrush and sand play a role. On the one hand, the rapid advance of the working face of the dynamic deformation process Shortened, the better compaction effect of overlying strata is nearly the whole continuous deformation. On the other hand, the rapid advance of the broken rock between the fractured time and rapid structural closure, thereby preventing the formation of water channel, also prevents the collapse of water and sand the occurrence of broken rock. Back to the angle of the general basic roof periodic weighting step length of direct control, namely the periodic weighting step distance will make more small rotation angle is greater, resulting in working face through the longitudinal crack growth degree is higher. The thin bedrock shallow generally face periodic weighting is relatively small the longitudinal through cracks not through the basic does not exist, the speed of working face must have good control. The cycle pressure before, by means of grouting blocking live through vertical fissures, avoid the formation of water channel sand; pressure, vertical fracture Immediately start a structural closure, can not do. So, the speed of working face must have good control, especially in the bedrock cycle pressure, appropriate to accelerate, avoid intermittent pauses, to reduce the inrush of sand water inrush accidents. The increase of supporting force of hydraulic support field work to reduce rock cutting the rotation angle before the rock must be ensured and the support function of hydraulic resistance area, this causes the longitudinal through cracks in small size directly after fast cutting, longitudinal through cracks quickly closed. At the same time, in the stage of crack closure and suspension working face advance grouting process for maintenance, security risks to a minimum. In addition, the geometric relationship between the roof and the support beam, should to pay great attention to the support support force, strengthen the supporting force of support beam, weakening the shield for Use. To reduce the exposure time and area of the roof, roof weakening thin bedrock bearing capacity low. The water rich area mining thick limit bedrock breaking block rotary deformation space is mainly affected by the degree of filling the goaf, the larger Zhi empty space makes the goaf filling degree is relatively low, directly lead to broken broken rock rotating angle becomes larger, thus, increase the working face through vertical fissures. Therefore, water rich area may be appropriate to reduce the mining height, increase the thickness of immediate roof corresponding directly increase postharvest gangue filling degree of goaf, in order to reduce the broken rock turning, mining thick limit at the same time also accelerate the speed of working face, there is conducive to rapid closure of overburden longitudinal through cracks, reduce the inrush of sand water bursting accidents. (5) the formation of working face water inrush and sand control method, and the engineering practice for shallow buried thin bedrock coal seam, with the Coal mining, overlying rock fissure conducting loose water bearing alluvium, upper water will be along with the water seepage. Reliable setting resistance, ensure working face in broken rock blocks under not large crack; and to promote the speed of the broken rock and as soon as possible the working side not broken rock in the cross section is hinged with the lower end of structural and squeeze the closed, and compacted in overburden under vertical load, so as to effectively control the rock fracture rate, permeability, water conductivity. The exploitation of Chang Han Gou mine 201 working face, the cycle in different regions to work pressure position whether there is pressure, near the inrush of sand water bursting or collapse of water and sand signs for the statistics, statistical results show that the speed of the reasonable arrangement of work, comprehensive prevention and control of water inrush of sand crushing method to increase hydraulic support force, advancing working face During the period, the hidden danger of sand break and sand break was not appeared, which realized the safety and efficient mining of the mine.

【学位授予单位】：中国矿业大学(北京)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TD32

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