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.

Stress distribution and surrounding rock control of mining near to the overlying coal pillar in the working face

The occurrence of overlying coal pillar(OCP)exerts a strong effect on the stress and strain distribution of the surrounding rock in the stope.In this paper,the stress distribution characteristics are analyzed via the numerical calculation with the account of OCP presence or absence.In addition,this study revealed the joint effect of side pressure relief area of the goaf and stress concentration in OCP on the final stress distribution.Furthermore,the rules of abutment stress distribution affected by three influencing factors,namely horizontal-vertical distances between OCP and working face and buried depth of OCP,are analyzed.The functional model linking the peak stress of surrounding rock with the above influencing factors is developed.The field application of the above results proved that the rib spalling and deformation of a 2.95 m-high and 5.66 m-wide roadway could be efficiently controlled by rationally adjusting working states of the support,and adopting the hydraulic prop coordinated with the p type metal beam and anchor cable to strengthen the surrounding rock of working face and roadway,respectively.The proposed measures are considered appropriate to satisfy the safe operation requirements.

Deformation of mining caving zone grouting compound rock under overlying strata pressure

To solve the problem of surface subsidence caused by mining,the main method is to reasonably process coal mining space.'Mining caving zone high-pressure grouting pulverized coal ash hydromass controlling roof and overlying strata movement' technology is one of processing methods.After grouting pulverized coal ash hydromass in mining caving zone,formed one kind of special material which is used to support roof and effec- tively control the subsidence of overlying strata.For the accurate calculation of roof mining subsidence at grouting state,based on the characteristics of such materials,established its constitutive equation based on certain assumptions,gave deformation calculation method when the compound rock supports overlying strata,lay foundation for the actual calculation of subsidence of overlying strata after grouting and the promotion of mining caving zone grouting technology.

RESEARCH ON THE SEROSITY DURING INJECTING CLAY GROUTS INTO THE OVERLYING ROCK STRATA

On the basis of the mechanism study of injecting clay grouts into overlying strata, the clay grouts are researched in greater detail from three aspects. The flowing state of clay grouts in the strata——the pattern of different direction flowing around a point source is advanced and the flowing equation is put forward which is correspond with experiment result, and the corresponding mechanical model is set up which has its formulistic study, and the function of clay grouts is also discussed after the water in it has been lost, at the same time the concept of similar rock in effective supporting zone is given. It would draw great positive inspiration from what studied in this paper for studying on drawing down the surface subsidence by injecting.

Mining-Induced Seismicity in the Kola Peninsula Mines

Mining-induced seismicity is a reflection of rock geomechanical evolution of geological environment in the natural and man-made systems and in the mining-technical systems. In order to predict and prevent mining-induced seismicity, it is necessary to research geodynamics and stress state of intact rock mass, to determine possible deformations and additional stresses as a result of large-scale rock extraction, conditions of accumulated energy release. For that a geodynamical monitoring is required on every stage of deposit development and a closing. The report considers principal influencing factors of preparation and occurrence of mining-induced earthquakes. Also it estimates precursors and indicators of rock mass breaking point, and experience concerning prediction and prevention of mining-induced seismicity in the Khibiny apatite mines in the Murmansk region, which is the largest mining province.

Physical model of overlying rock movement law in Yuwang coal mine

With the increase in mining depth,traditional coal mining methods not only waste coal resources but also seriously impact the stability of the roadway support structure during the collapse of the overburden rock.In contrast,the top-cutting and depressurization technology utilizes the expansion effect of the rock effectively.This technology allows the rock body to collapse entirely,filling up the mining area through active intervention,which reduces the subsidence height of the overburden rock and significantly improves the coal extraction rate in the mining area.This study utilizes 3D seismic exploration technology to analyze the spatial distribution characteristics of fissure zones and rich zones of the rock strata in the mining area and investigate the movement law of overburdened rock during the coal seam mining process using the 110 mining method.It conducts numerical analysis combined with geomechanical modeling experiments to explore the movement law of the overburden rock under the influence of mining activities at Yuwang Coal Mine.The numerical analysis results indicate that the horizontal and vertical displacements of the rock body on the roof of the roadway are minimal when the angle of the slit is 75°.The overlying rock movement during the test is categorized by modeling the stress and strain fields into the following stages:fracture zone expansion,collapse zone gestation,rapid collapse zone development,and overlying rock stabilization.The rock on the cut side collapses more completely,breaking up and expanding to support the overburden,effectively reducing the depth of crack expansion and the extent of rock settlement and deformation.The integrity of the roadway roof remains intact during the rock collapse under NPR anchors.This study provides a scientific basis for understanding the movement law of overlying rock and for controlling the stability of the roadway perimeter rock in kilometer-deep underground mining.

Research on the relation between rock burst and movement of strata and surface

Large-scale bed separation in bending strip upside cranny strip was brought by un-consistency of overlying strata subsidence movement due to under surface mining. Different characteristic of movement and deformation of overlying strata and surface include periodic caving of bed separation interspaced along with work face mining. Conglomerate rock layer movement is the main power fountain of rock burst on the basis of locale observation. And rock burst moves periodically adapted to movement of deep conglomerate rock layer which had similar characteristic with main roof. Practice indicates this method that forecasting and prediction using correlation information of movement of strata and surface is feasible and has reference meaning for similar stope.

Fracture distribution in overburden strata induced by underground mining

Coal-mining activities give rise to a series of ecological environmental problems,such as ground settlement and groundwater pollution.In fact,they are mainly caused by mining-induced fractures.Hence,it is necessary to study the mining-induced fracture distribution to identify the behavior of rock mass movement.However,the fractures in overburden strata cannot be directly measured owing to the special condition.Therefore,the majority of previous studies are based on experiments or experience.For this reason,this study first used a discrete element method to simulate the shape of mining-induced fractures in overburden strata.Then,a geophysical tool of transient electromagnetic method(TEM)was used to investigate the mining-induced fracture distribution.Based on the low-resistivity anomaly area,the water-rich area in overburden strata was analyzed to be mainly caused by fracture seepage.Through the mutual authentication between numerical simulation and TEM results,the mining-induced fractures in overburden strata were explored.This study can enhance the understanding of mining-induced fracture distribution on the one hand and guarantee the coal mining safety on the other,thus guiding the coordinated development between coal mining and environmental protection.

深井跨采巷道群开采扰动模拟分析与围岩控制对策研究

针对工作面开采扰动下底板巷道围岩控制难题,以安居煤矿1315工作面跨采底板巷道群为研究背景,通过数值模拟及现场实践的方法,分析了上覆工作面回采过程中巷道围岩的应力和塑性区分布特征。研究结果表明:工作面推进至终采线100 m时,超前支承压力在水平方向影响范围约35.8 m,在竖直方向影响范围约37.8 m。底板巷道按照到工作面距离的大小先后受到回采影响,具有过程性。针对3_(上)煤底板巷道群围岩受扰动变形等特点,提出“锚网索+T型钢带+金属网”联合支护技术方案。现场监测表明,支护方案对底板巷道群围岩变形量控制效果显著,确保了工作面下覆巷道群在回采期间的稳定使用。

煤层自封闭性对深层煤岩气的富集与改造意义

近年来,煤岩气勘探开发成功突破“深度禁区”,将中国煤岩气产业带入了一个新的发展阶段。深层煤岩气富集规律以及“千方砂,万方液”的超大规模储层压裂改造工艺无不与中、浅层煤岩气的富集规律和勘探开发技术形成鲜明对比,进一步彰显了深层煤岩气成藏、富集及开采的特殊性。为进一步明确有利于深层煤岩气富集、储层改造的地质-工程甜点纵向分布,推动实现深层煤岩气地质-工程一体化发展,以华北地区深层煤岩气为研究对象,基于土力学中超固结比的概念定量表征了煤储层的自封闭性,评价了深层煤岩气的富集条件和煤储层的可改造性。研究结果表明:①超固结比能够反映煤储层自封闭性的动态演化特征,与煤层埋藏深度具有耦合关系;②埋深越大,煤层超固结比越小,煤储层自封闭性越强,有利于煤岩气的富集,但煤储层压裂改造难度增大;埋深越浅,煤层超固结比越大,煤储层自封闭性越弱,不利于煤岩气的保存,但煤储层相对易于压裂改造;③基于煤层超固结比与埋深的耦合关系揭示了既有利于煤岩气富集又利于煤储层改造的深度范围,该深度带是深层煤岩气地质-工程甜点区带。结论认为,基于超固结比确定的地质-工程甜点深度界限可为相似地质背景条件下的深层煤岩气地质-工程一体化实施提供参考和借鉴,有助于煤岩气产业的高质量发展。

Optimal mining sequence for coal faces under a bedding slope:insight from landslide prevention

Repetitive mining beneath bedding slopes is identified as a critical factor in geomorphic disturbances, especially landslides and surface subsidence. Prior research has largely concentrated on surface deformation in plains due to multi-seam coal mining and the instability of natural bedding slopes, yet the cumulative impact of different mining sequences on bedding slopes has been less explored. This study combines drone surveys and geological data to construct a comprehensive three-dimensional model of bedding slopes. Utilizing FLAC3D and PFC2D models, derived from laboratory experiments, it simulates stress, deformation, and failure dynamics of slopes under various mining sequences. Incorporating fractal dimension analysis, the research evaluates the stability of slopes in relation to different mining sequences. The findings reveal that mining in an upslope direction minimizes disruption to overlying strata. Initiating extraction from lower segments increases tensile-shear stress in coal pillar overburdens, resulting in greater creep deformation towards the downslope than when starting from upper segments, potentially leading to localized landslides and widespread creep deformation in mined-out areas. The downslope upward mining sequence exhibits the least fractal dimensions, indicating minimal disturbance to both strata and surface. While all five mining scenarios maintain good slope stability under normal conditions, recalibrated stability assessments based on fractal dimensions suggest that downslope upward mining offers the highest stability under rainfall, contrasting with the lower stability and potential instability risks of upslope downward mining. These insights are pivotal for mining operations and geological hazard mitigation in multi-seam coal exploitation on bedding slopes.

四川省大渡河金川水电站地下厂房岩壁吊车梁岩台超挖处理措施及锚杆注浆时机研究

为了解决金川水电站地下厂房岩壁吊车梁岩台超挖严重问题,综合考虑现场地质状况、开挖现状、施工条件以及后续开挖可能进一步加剧围岩劣化等因素,对岩台超挖部分实施混凝土回填,并与岩壁吊车梁同期施工。通过建立岩壁吊车梁和回填混凝土及围岩三维有限元数值模型,计算分析了洞室下部开挖过程中的洞壁应力释放和桥机轮压、受拉锚杆注浆时机对岩壁吊车梁受拉锚杆应力以及壁吊车梁应力影响。结果表明:岩壁吊车梁锚固锚杆应力主要受洞壁应力释放影响,轴向拉应力最大值位于岩体中,桥机轮压影响幅度仅为0.32~3.15 MPa;岩壁梁锚固锚杆不宜与系统锚杆同时注浆。岩壁吊车梁运行状态良好,满足稳定要求。

采煤过断层期间围岩变形破坏数值模拟研究

为有效控制煤体掉落风险,降低采煤过断层期间的不良影响,通过理论分析结合数值模拟对工作面过断层围岩破坏情况进行分析,发现随着工作面的推进,工作面与断层之间的距离逐渐减小,断层对顶板岩层的影响逐渐增大。在底面通过顶板之前,无论是前方煤壁的应力减小区还是增大区都在持续向前推进,而应力集中区的范围呈现出先增大后减小的趋势,为后续过断层围岩支护提供一定的参考。

基于沿空留巷技术的工作面过陷落柱工程实践

矿井采掘工作揭露陷落柱等地质构造时,往往会带来较多潜在隐患,可能导通含水层、造成瓦斯超限和形成支护难题等。针对6102工作面揭露大型陷落柱影响区的技术难题,矿方根据陷落柱产状及潜在的隐患情况,结合矿井较成熟的沿空留巷理论及经验,成功实施了基于沿空留巷技术的过陷落柱工程实践,在损失一定保护煤柱的代价下,确保了工作面安全快速跳过陷落柱影响区域,沿空留巷技术优势得到验证。

饱和破碎岩石压实变形特性的试验研究

破碎岩石的变形性质是影响采空区覆岩垮落与地表沉陷的重要因素。利用一种专门的破碎岩石压实试验装置,在MTS815.02岩石力学试验系统上完成了饱和破碎岩石压实过程中的变形特性测定,得到了煤、页岩和砂岩3种岩样压实过程中的应力–应变关系,分析了粒径和强度对破碎岩石应力–应变特性的影响。研究结果表明:破碎岩石在压实过程中应力与应变之间近似呈指数关系;在相同的应力状态下,岩块强度越高试样应变越小;大粒径试样在加载初期应变增长率小于小粒径试样的应变增长率,随着应力的增加,大粒径试样的应变增长率大于小粒径岩样的应变增长率;饱和破碎岩石在相同的应力状态下的应变明显比在自然含水状态下大。

含油气盆地深部高过成熟烃源岩古 TOC 恢复方法及其应用

根据烃源岩演化过程中残留生烃母质变化原理，建立了 TOC 恢复的数学地质模型，提出了 TOC 演化与各种主控因素之间的定量关系模式，通过对模式中各主控因素在自然条件下变化的特征取值，计算得到了TOC 恢复系数，做出了泥质岩烃源岩和碳酸盐岩烃源岩在含不同类型干酪根情况下的 TOC 演化图版。这一方法的最大特色是避免了人为主观因素和高温压物理模拟实验条件可能带来的结果偏差。研究表明：随着热演化程度的增加，烃源岩内残留的 TOC 含量逐渐减少，在大量生排烃阶段（RO ＝0.5％～2.0％）变化幅度最大；处于高过成熟阶段（RO ＞1.2％）的烃源岩，其原始 TOC 恢复系数随 RO 增大而逐渐增加，含Ⅰ型、Ⅱ型、Ⅲ型母质的泥质岩烃源岩 TOC 恢复系数分别可达3.0、2.0、1.4；含Ⅰ型、Ⅱ型、Ⅲ型母质的碳酸盐岩烃源岩 TOC 恢复系数分别可达3.2、2.2、1.5。论文例举了源岩 TOC 恢复在实际工程中的应用。

烃源岩过成熟阶段生气潜力的实验室模拟

源岩生气潜力的定量评价主要以实验室模拟为手段,由于技术条件的限制,模拟温度一般最高到600℃,认为生气能力已经耗尽,600℃之前的生气量就可作为源岩生气潜力评价的定量依据。而对于600℃之后的生气潜力到底有没有?有多少?一直存在着争议。为了定量评价源岩过成熟阶段的生气潜力,我们通过技术开发将实验温度提高到了1 000℃,通过大量的实验结果发现,源岩在600～800℃之间仍然可以生成大量的天然气,煤系源岩的生气量占总生气量的20%～30%甚至更多,而湖相和海相源岩在这一阶段的生气量相对少一些,约占总生气量的10%,这与其干酪根的骨架结构不同密切相关。天然气生成下限的向下延伸,进一步扩大了过成熟阶段天然气的资源基础,对指导深层勘探有重要意义。

万福煤矿深部水压致裂地应力测量

为了克服煤田上覆冲击层厚度高达700m所造成的困难,保证超千米深部地应力测量的成功,对传统水压致裂法测量方法和设备进行改进,增加测量系统的耐压能力和测试系统的精度。在完成的7个钻孔、37个测点的现场实测中,6个钻孔的深度接近和超过1100m,最大测点深度为1105m,创造了我国水压致裂法测量地应力钻孔深度的新记录。通过实测,确定了矿区的地应力状态及其分布规律。研究结果表明,37个测点的最大水平主应力与垂直主应力的比值为1.441～3.224,平均为1.97,反映了矿区地应力场以水平应力为主导的特点。测量结果可为矿山建设和开采设计提供科学的依据。

四川盆地震旦系—下古生界高过成熟烃源岩演化史分析

四川盆地震旦系-下古生界烃源岩处于高过成熟度阶段，其Ro一般为2．36％～3．39％。根据埋藏史及古地温梯度，应用改进了的Karweil方法，将该烃源岩划分成4个演化阶段，并依据高科1井、盘1井和五科1井等重点井进行系统成熟度模拟，使之与实测的成熟度值一致，结果表明四川盆地西南部坳陷震旦系-下古生界烃源岩生烃最早，东部地区次之，乐山-龙女寺古隆起最晚，具体情况是：高科1井下寒武统烃源岩主生油期在中休罗世，主生气期在晚侏罗世-早白垩世，盘1井下寒武统烃源岩主生油期在二叠纪，主生气期在晚三叠世；五科1井下寒武统烃源岩主生油期在早三叠世，主生气期在早中侏罗世；盘1井志留系烃源岩主生油期在晚三叠世，主生气期在中侏罗世，五科1井志留系烃源岩主生油期在早侏罗世，主生气期在晚侏罗世。

深埋洞室地应力状态与岩爆相关性研究

为了研究锦屏二级水电站探涧开挖过程中发生岩爆与地应力的相关性，在电站探洞不同水平埋深处进行了水压致裂和应力解除三维应力测量。测量结果表明：（1）在探洞浅部，受局部地形影响，测点的应力分布主要受自重和区域及地形地貌控制。形成特有的“V”型河谷岸坡内的局部应力状态，最大主应力11．0MPa左右，作用方向NNW基本近水平；（2）在探洞深部地应力值较高，最大主应力40．0MPa左右，作用方向近直立；（3）随水平埋深的增大最大主应力由近水平状态转变为近直立状态，说明在洞深部自重应力起主导作用。对原地应力实测结果进行解析，得到了隧道横截面的最大主压应力和最小主压应力及相关的应力参量，结合岩爆判据对隧道发生岩爆的可能性进行了分析，提出了岩爆的发生主要受控于隧道横截面内的最大差应力的大小。