ASR法在井下矿山地应力测试中的应用前景分析

现今地应力状态是井下矿山建设、巷道稳定性分析和冲击地压（煤与瓦斯突出）预测等方面的重要基础数据。目前井下矿山地应力测试主要以空芯包体解除法为主,实践中发现空芯包体解除应力计安装过程中,易出现不能与孔壁完全黏贴的情况,导致测试成功率较低且劳动强度较大。文章介绍了一种基于定向岩芯卸荷后非（滞）弹性恢复变形测量的近原位地应力测试方法（简称ASR法）,并通过与水压致裂地应力测试结果对比,验证了ASR地应力测试方法的有效性。ASR法的可重复性结果表明,同一测点ASR地应力测量结果平均差系数最大为6.29%,验证了ASR地应力测量方法的可靠性。预期ASR法以其安全、高效且不受测量深度和测试环境限制等优点,在井下矿山地应力测试中具有广阔的应用前景。      

淮南矿区地应力条件及其对煤层顶底板稳定性的影响

通过现场地应力测量和理论分析以及数值模拟计算,研究了淮南矿区地应力分布规律,探讨了圆形硐室围岩应力分布和不同侧压下回采工作面顶板稳定性分布。研究结果表明:淮南矿区原岩应力主要表现为自重应力场,除局部构造应力集中外,不存在高构造应力;区内侧压力系数λ值一般为0.49~1.49,平均为0.92,并且与测点距地表深度有一定的趋向性,表现为在浅部λ值较大,变化范围也大,而在深部λ值渐小,变化范围也缩小;回采工作面顶底板稳定性与侧压系数λ的大小密切相关,且随侧压系数λ的增大,顶板垂直位移减小,顶板岩层易于形成结构平衡而保持稳定,但底板垂直位移量增大,且易于形成底鼓破坏。这些认识为研究区煤层顶底板岩层支护控制提供了科学依据。     

红庆梁煤矿地应力场特征及巷道稳定性分析

针对红庆梁煤矿回采巷道变形严重问题,采用空心包体地应力测量方法对红庆梁煤矿3-1煤的地应力进行了实测,获得地应力场分布特征。应用地质动力区划法划分红庆梁井田Ⅰ—Ⅴ级断裂构造,应用“岩体应力状态分析系统”,进行应力区划分和巷道稳定性分析。研究表明：红庆梁煤矿地应力场属于以水平压应力为主导的水平构造应力场,地应力场方向对巷道稳定性影响较小;井田范围内共划分4个应力区：低应力区、正常应力区、应力梯度区、高应力区,分别占井田面积的5.9%、55.7%、27.0%、11.4%;应力大小是影响巷道稳定性的主要原因,致使处于应力梯度区和高应力区内的巷道变形严重。地应力场的分布特征分析和应力区的划分对红庆梁煤矿及类似条件矿井的采掘部署和支护设计具有重要作用。移动阅读     

西部地应力测量与岩爆分析

通过对我国西部一些重点工程的地应力测量,大致得出西部工程的应力状态,并从实测地应力资料出发,采用现有的、普遍应用的岩爆判别准则,对这些工程在施工开挖期间的地下工程进行岩爆预测分析。     

Coal Mine Roadway Stability in Soft Rock: A Case Study

Roadway instability has always been a major concern in deep underground coal mines where the surrounding rock strata and coal seams are weak and the in situ stresses are high. Under the high overburden and tectonic stresses, roadways could collapse or experience excessive deformation, which not only endangers mining personnel but could also reduce the functionality of the roadway and halt production. This paper describes a case study on the stability of roadways in an underground coal mine in Shanxi Province, China. The mine was using a longwall method to extract coal at a depth of approximately 350 m. Both the coal seam and surrounding rock strata were extremely weak and vulnerable to weathering. Large roadway deformation and severe roadway instabilities had been experienced in the past, hence, an investigation of the roadway failure mechanism and new support designs were needed. This study started with an in situ stress measurement programme to determine the stress orientation and magnitude in the mine. It was found that the major horizontal stress was more than twice the vertical stress in the East–West direction, perpendicular to the gateroads of the longwall panel. The high horizontal stresses and low strength of coal and surrounding rock strata were the main causes of roadway instabilities. Detailed numerical modeling was conducted to evaluate the roadway stability and deformation under different roof support scenarios. Based on the modeling results, a new roadway support design was proposed, which included an optimal cable/bolt arrangement, full length grouting, and high pre-tensioning of bolts and cables. It was expected the new design could reduce the roadway deformation by 50 %. A field experiment using the new support design was carried out by the mine in a 100 m long roadway section. Detailed extensometry and stress monitorings were conducted in the experimental roadway section as well as sections using the old support design. The experimental section produced a much better roadway profile than the previous roadway sections. The monitoring data indicated that the roadway deformation in the experimental section was at least 40–50 % less than the previous sections. This case study demonstrated that through careful investigation and optimal support design, roadway stability in soft rock conditions can be significantly improved.     

Regional and economic geology of Pennsylvanian age coal beds of West Virginia

West Virginia is the only place in the United States where an entire section of Pennsylvanian age (Upper Carboniferous) strata can be seen. These strata occur within a wedge of rock that thins to the north and west from the southeastern part of the State. The progressive north-northwesterly termination of older Pennsylvanian geologic units beneath younger ones prominently outlines the center of the Appalachian basin of West Virginia. Over most of West Virginia, Lower and/or Middle Pennsylvanian strata unconformably overly Upper Mississippian (Lower Carboniferous) strata. Sediment deposition was accomplished by a complex system of deltas prograding north and west from an eastern and southeastern source area.More than 100 named coal beds occur within the Lower, Middle, and Upper Pennsylvanian rocks of West Virginia and at least 60 of these have been or are currently being mined commercially. Collectively, these coal beds account for original in-ground coal resources of almost 106.1×10⁹ t (117×10⁹ tons). West Virginia ranks fourth in the United States in demonstrated coal reserves. In 1988, West Virginia produced 131.4×10⁶ t (144.9×10⁶ T) of coal, third highest in the United States. Of this annual production, 75% was from underground mines. In 1988, West Virginia led the nation in the number of longwall mining sections currently in place. West Virginia's low-volatile coal beds are known worldwide as important metallurgical-grade coals, while the higher-volatile coal beds are utilized primarily for steam production.     

开滦矿区地应力场特征及其研究意义

地应力是影响矿井突水的重要因素之一,是存在于地壳中的重要能量场条件。采用现场应力解除法对开滦矿区多个矿井进行了地应力测试,分析了研究区现今地应力分布规律,在此基础上,建立了煤层底板突水危险性与岩石力学性质及地应力之间的相关关系和模型,对范各庄矿12煤层底板和东欢坨矿12-2煤层底板突水危险性进行了评价。研究结果表明,本区地壳浅部现代地应力作用较强,整体处于近东西向挤压应力场中,在挤压应力作用下,煤岩层应力状态主要表现为水平主应力大于垂直主应力,原岩应力主要由构造应力和自重应力场构成。煤层底板突水危险性受岩石力学条件和地应力所控制,当岩石破裂压力大于水压（Pf〉Pw）,则不产生突水;若岩石破裂压力小于水压时,则有可能突水。当承压水的水压（Pw）小于最小水平主应力（σhmin）时,不会产生突水。只有当承压水的水压（Pw）大于最小水平主应力（σhmin）时,存在突水危险性。范各庄矿12煤层底板和东欢坨矿12-2煤层底板破裂压力（Pf）和最小主应力（σhmin）均大于其底板岩体承受的水压（Pw）,本区在无构造破坏卸压条件下是不会发生底板突水的。     

Effect of Tunnel Shape and Support System on Stability of a Tunnel in a Deep Coal Mine in China

Stability level of tunnels that exist in an underground mine has a great influence on the safety, production and economic performance of the mine. Ensuring of stability for soft-rock tunnels is an important task for deep coal mines located in high in situ stress conditions. The aim of this study is to investigate the effect of tunnel shape and support pattern on the deformation, failure zone and stability around a tunnel located in a coal rock mass in China and to select an appropriate tunnel shape and a support pattern to provide a stable stress-deformation condition around the tunnel. Using the available information on stratigraphy, geological structures, in situ stress measurements and geo-mechanical properties of intact rock and discontinuity interfaces, a three-dimensional numerical model was built using the FLAC software to simulate the stress conditions around the tunnel in the coal rock mass. Analyses were conducted for several tunnel shapes and rock support patterns. Results obtained for the distribution of failed zones, and stress and displacement fields around the tunnel were compared to select the best tunnel shape and support pattern to achieve the optimum stability conditions. Also, a comparison is given between the numerical predictions and field deformation monitoring results.     

深部矿井地应力场分布规律及其在冲击地压预测中的 应用

以徐州张小楼矿井埋深1200m深部采区为例,在区域地应力场宏观分析基础上,用AE法测试了采区不同深度岩层地应力值,采用软岩地应力估算方法估算了不同岩层中地应力值大小;采用数值模拟法,对采区深部地应力场进行了反演计算。在此基础上,测试分析了主采煤层冲击倾向性指标,评价了深部开采冲击地压危险性并进行了预测分区。研究成果对指导该矿井深部安全生产具有重要意义,对我国其他深部矿井开采冲击地压预测预报具有普遍指导意义。     

倾斜煤层水力压裂起裂压力计算模型及判断准则

针对目前倾斜煤层起裂机制不明确,导致水力压裂时盲目升高压力或增大注水量来增加煤层透气性的问题,根据最大拉应力理论,分析真实环境下倾斜煤层压裂钻孔周围应力状态,建立压裂钻孔周围煤岩体起裂压力计算模型及判断准则,并在重庆松藻煤电公司同华煤矿进行了验证,结果表明,根据实测压裂区域地应力状态,起裂压力随煤层倾角增大而增大,钻孔起裂位置随煤层倾角增大逐渐向走向方向偏转;现场试验起裂压力与理论计算相符,随煤层倾角增大而增大,从而验证了计算模型的正确性。     

潞安矿区井下地应力测量及分布规律研究

在山西潞安矿区的13个煤矿采用小孔径水压致裂地应力测量装置,完成了60个测点的原岩应力测量工作。实测数据表明：潞安矿区55%的测点最大水平主应力大于垂直主应力,由于受埋藏深度与地质构造影响,矿区内各矿地应力值差别较大,但地应力大小总体上属于中等地应力值;潞安矿区最大水平主应力方向从南到北变化较大,构造应力场呈现出多变的形态。在实测数据的基础上,绘制了潞安矿区地应力分布图;分析了地应力随埋藏深度的变化规律、平均水平主应力与垂直主应力的比值与埋藏深度的关系。煤矿井下地应力测量为井田开拓、巷道布置与支护设计等工程实践提供了可靠的基础参数,提高了工程设计的科学性、合理性与可靠性。     

Geomechanical evaluation of a coal mine arched entry

Summary In an effort to minimize cutter roof failures in longwall development entries of a West Virginia coal mine, a three-entry system was developed with the center entry arched into the strata above the coal seam. The purpose of the arched entry was to modify the horizontal stress envelope associated with the three-entry system and improve roof conditions in the adjacent outside entries.Contrary to the predictions of elastic analyses, the presence of the arched entry improved roof conditions by eliminating cutter roof failures in the outside entries.In situ stress determinations and numerical modeling techniques were employed to quantify the impact of the arch and investigate the mechanism of stress relief associated with the arched entry. Stress determinations and underground observations indicated that the roofs of the outside entries were within the zone of stress relief generated by the arch, and that failure or movement along bedding plane discontinuities played a major role in the formation of the stress relieved zone. The numerical model incorporated horizontal joints to simulate bedding plane discontinuities. The properties of the joints were adjusted until roof stresses predicted by the model were in agreement with measured stress profiles. This process resulted in a calibrated analytical tool that could be used to evaluate alternate mining geometries.     

朱仙庄煤矿南翼地应力原位测试及其最优化反分析

地应力在软岩或深部煤矿设计、施工与安全生产中具有重要作用。采用空心包体应变计法对朱仙庄煤矿南翼II、III水平进行了地应力原位测试,获得了该矿地应力大小及主要方位;以此作为约束条件,基于多目标约束的最优化方法利用ANSYS软件建立了朱仙庄煤矿南翼地应力最优化反分析模型,反演得出了最优边界条件,并用数值分析了该区域地应力分布特征和变化规律。结果表明：朱仙庄煤矿南翼地应力以水平构造应力为主,且具有明显的方向性,最大主应力值变化范围是20~25 MPa,方位则分布在N 60°E和N 75°E之间,其水平地应力非均匀系数为1.1~1.8。     

基于复杂地质体的地应力场智能识别方法研究

初始地应力是地下开采及施工所需要考虑的重要影响因素,地应力值的准确获得通常采用现场测量与反演计算结合实现。针对某铜镍矿复杂地质体,在已有监测数据的基础上建立三维正交数值模型,获得监测点的地应力计算值。利用遗传规划程序,回归地应力监测点的地应力与各自变量的函数关系。建立地应力实测值和计算值之差的平方和最小的目标优化函数,使用遗传算法智能算法对目标函数进行优化,最终获得了矿区的原岩应力场。检测样本验证结果显示,计算值与实测值的误差控制在10%以内,一定程度上证明了该地应力场智能识别方法的可靠性,可为以后复杂地质体矿区地应力场的计算提供较为可行的研究方法。     

基于巨厚岩层-煤柱协同变形的煤柱稳定性

采前煤柱稳定性研究是工作面冲击危险性评估和开采方案设计的关键。以山东某矿深井巨厚砾岩条件工作面开采遗留煤柱为背景,采用案例调研、理论分析、数值模拟和工程实践等方法,对巨厚岩层-煤柱协同变形机制及其煤柱稳定性进行了研究,建立了巨厚岩层-煤柱协同变形的简化力学模型,探讨了引起煤柱变形的主要应力来源和变形形式,推导了在协同变形条件下煤柱的应力-应变关系。以此为基础,综合煤柱煤体应力、围岩稳定性和变形特征等条件,提出了煤柱整体失稳的力学判据。研究结果表明：巨厚岩层-煤柱失稳诱发冲击与煤柱的位置、尺寸和上覆岩层运动或变形关系密切,上覆岩层运动或变形是诱发煤柱失稳的动力因素;巨厚岩层-煤柱的变形主要包括受集中力F压迫的协同挠曲压缩变形和受集中力G作用的重力沉降变形,二者保持内在协调性;巨厚岩层下煤柱整体失稳的工程判据为煤柱煤体平均支承应力p超过其平均极限支承强度Rc（p≥Rc）;评估得到遗留的50 m煤柱具有强冲击危险性,并通过优化开采设计,取得了良好的效果。该研究成果对相似条件煤柱留设及其稳定性分析具有参考意义。     

Evaluation of the Effect of Fault on the Stability of Underground Workings of Coal Mine through DEM and Statistical Analysis

The rock mass around an excavation is generally traversed by different geological discontinuities such as faults, folds, slips, joints, etc. Fault is one of the major geological discontinuities which creates lot of difficulties during underground winning of coal. Entire stress regime and ground conditions in the formation are altered in and around the faults. Faults also impose detrimental effects by introducing impurities, including clay and various forms of mineral matter into the coal seams; opening of pathways for the influx of water and gas into the underground workings; displacing the coal seams upward/downwards making the coal seams difficult or sometimes impractical to mine. Appropriate evaluation of the effect of the fault on the stability of the underground workings is a requisite for safe design of the underground mining structures. In this paper, a study has been carried out to assess the effect of the fault on the stability of underground coal mines by numerical simulation with distinct element method (DEM). On the calibrated DEM model, parametric study has been performed by varying the selected parameters, the dip and the friction angles of the fault. The analysis of variance (ANOVA) shows that both the factors have statistically significant effect on the strength of the coal pillar. Similarly, the displacement of the immediate roof and the height of the disturbed strata are evaluated by the DEM modelling and statistical analysis when the fault passes through the middle of the gallery. The results of ANOVA for both cases indicate that the both factors have significant effect on the displacement of the immediate roof and the height of the disturbed strata. It is obtained from the study that the low angle fault causes high instability in the immediate roof. The paper has been supplemented with the field observations where instability in underground roadways of a coal mine in India is caused by the fault. It was observed in VK-7 incline mine of Singareni Collieries Company Limited, India that there was sudden failure of immediate roof of a roadway where a low angle fault crosses the middle of the roadway. The findings of the paper help to understand the behaviour of the coal pillar and the surrounding rock mass in the presence of the fault. The study would also help to take appropriate decisions about the unstable regions of the working safeguarding safety in underground coal mines.     

煤矿地下水库岩体碎胀特性试验研究

鉴于岩石碎胀特性对于煤矿地下水库储水能力及地表沉陷的重要影响,选取神东矿区某矿22615面为工程背景,利用相似材料模型试验探究采空区垮落岩体应力及碎胀系数分布规律,明确垮落岩体应力-碎胀系数关系,并通过岩石压实试验进行验证,揭示饱水岩石压实特性。研究结果表明：沿采空区走向,边界附近老顶悬臂梁结构限制覆岩下沉,垮落岩体应力最低仅为0.32 MPa,碎胀系数最大达1.48;中间区域老顶结构失稳覆岩完全下沉,垮落岩体应力趋于1.5 MPa,碎胀系数降至1.09。沿采空区垂向,垮落岩体应力随高度负相关改变,而碎胀系数成正相关变化。无论沿采空区走向或垂向,垮落岩体碎胀系数与应力均满足负对数关系。与自然岩石相比,受载饱水岩石碎胀系数减幅更为明显,两者相差8.514%,为煤矿地下水库储水量和地表沉降量预测提供了基础理论依据。     

呼鲁斯太矿区煤层瓦斯分布规律及其控制因素探讨

根据煤矿井下煤层瓦斯参数测定结果,以瓦斯地质理论为基础,分析了呼鲁斯太矿区瓦斯分布规律及其控制因素。结果表明:矿区煤层瓦斯区域分布具有不均衡性,以F2-2和F22断层为界将矿区划分为北部、中部、南部三个区域,中部煤层瓦斯压力、瓦斯含量最高,北部次之,南部最低;煤变质程度较高和围岩封闭性较好是矿区瓦斯富集的根本条件,而构造复杂程度的不同、构造线方向的改变是瓦斯分布不均的主控因素。矿区中部为北北东向构造向东西向构造转折区,应力集中,且顶板为泥岩,煤变质程度较高,形成较好的瓦斯生储条件;南部北北东向推覆构造较为强烈,使煤层沿倾向切割,断层连通地表,造成瓦斯大量逸散。     

Evolution and effect of the stress concentration and rock failure in the deep multi-seam coal mining

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.     

八宝山煤矿北部正长斑岩岩体的产状及其意义

从岩体的岩性、时代、产状等方面,论证了八宝山煤矿北部的正长斑岩体为一岩盖,下部找煤前景可观,可在井下实施巷探和定向钻探找煤,以延长矿井寿命