Study on mechanism and practice of surrounding rock control of high stress coal roadway

The mechanical principle and surrounding rock deformation feature of highstress coal roadway was analyzed.The condition of stress balance of the kind of theroadway was put forward.The surrounding rock control principle and supporting techniqueof high stress coal roadway were discussed.It was very important to control early daysdeformation of coal sides.The supporting strength is should increased,so the strengthloss of coal sides is decreased.The range of plastic fluid zone is reduced.The abovemention-ned principle is applied in industrial test,and the new supporting technique is ap-plied successfully.

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.

Surrounding rock control of gob-side entry driving with narrow coal pillar and roadway side sealing technology in Yangliu Coal Mine

Gob-side entry driving can increase coal recovery ratio, and it is implied in many coal mines. Based on geological condition of 10416 working face tailentry in Yangliu Coal Mine, the surrounding rock deformation characteristics of gob-side entry driving with narrow coal pillar is analysed, reasonable size of coal pillar and reasonable roadway excavation time after mining are achieved. Surrounding rock control technology and effective roadway side sealing technology are proposed and are taken into field practice. The results showed that a safer and more efficient mining of working face can be achieved. In addition, results of this paper also have important theoretical significance and valuable reference for surrounding rock control technology of gob-side entry driving with narrow coal pillar under special geological condition.

Study on creep deformation and energy development of underground surrounding rock under four‐dimensional support

There is an urgent need to develop optimal solutions for deformation control of deep high‐stress roadways,one of the critical problems in underground engineering.The previously proposed four‐dimensional support(hereinafter 4D support),as a new support technology,can set the roadway surrounding rock under three‐dimensional pressure in the new balanced structure,and prevent instability of surrounding rock in underground engineering.However,the influence of roadway depth and creep deformation on the surrounding rock supported by 4D support is still unknown.This study investigated the influence of roadway depth and creep deformation time on the instability of surrounding rock by analyzing the energy development.The elastic strain energy was analyzed using the program redeveloped in FLAC3D.The numerical simulation results indicate that the combined support mode of 4D roof supports and conventional side supports is highly applicable to the stability control of surrounding rock with a roadway depth exceeding 520 m.With the increase of roadway depth,4D support can effectively restrain the area and depth of plastic deformation in the surrounding rock.Further,4D support limits the accumulation range and rate of elastic strain energy as the creep deformation time increases.4D support can effectively reduce the plastic deformation of roadway surrounding rock and maintain the stability for a long deformation period of 6 months.As confirmed by in situ monitoring results,4D support is more effective for the long‐term stability control of surrounding rock than conventional support.

Characteristics of stress distribution in floor strata and control of roadway stability under coal pillars

给在煤支柱下面在车道支持遇到的困难，我们在车道稳定性上学习了压力分发和他们的效果的特征，用理论分析和数字模拟。当水平应力减少时，结果证明在一个煤支柱下面，在一个地板阶层的垂直应力增加。我们断定垂直、水平的应力之间的增加的差别是为包围岩石的变丑和在煤支柱下面的车道的失败的一个重要原因。基于这，我们在一个煤支柱下面建议一条车道的包围岩石的控制技术例如高力量和高对的门栓支持，打电报加强支持，单个水力由包围岩石的 grouting 与横梁支持和加强支撑，它成功地在一个煤支柱下面在一条车道的一个稳定性控制工程被使用了。

Deformation mechanism of high-stress and broken-expansion surrounding rock and supporting optimization based on the gray correlation theory

Aiming at the large deformation and support problems of high-stress and broken-expansion surrounding rock, and taking 1 000 m level roadway of Mine II in Jinchuan as the research object, an investigation on the deformation and damage of roadway surrounding rock and an analysis of its mechanism were carried out. The gray correlation theory was used in support scheme optimization design. First, causes and mechanism of deformation of the 1 000 m horizontal transport channel were analyzed through field investigation, laboratory test and data processing methods. We arguued that poor engineering geological conditions and deep pressure increases were the main factors, and the deformation mechanism was mainly the ground deformation pressure. Second, the gray correlation theory was used to construct supporting optimization decision method in the deep roadway. This method more comprehensively considers various factors, including construction, costs, and supporting material functions. The combined support with pre-stressed anchor cables, shotcrete layer, bolt and metal net was put forward according to the actual roadway engineering characteristics. Finally, 4 support schemes were put forward for new roadways. The gray relational theory was applied to optimizing the supporting method, undertaking technical and economic comparison to obtain the correlation degree, and accordingly the schemes were evaluated. It was concluded as follows: the best was the flexible retaining scheme using the steel strand anchor; the second best was the one using plate anchors on the top and rigid common screw steel bolt on the two sides; the third was; the rigid common screw steel bolt in full section of roadway; and the worst is the planished steel rigid support. The optimized scheme was applied to the 1000 m level of new excavation roadway. The results show that the roadway surrounding rock can reach a stable state after 5 to 6 months monitoring, with a convergence rate less than 1 mm/d.

多煤层重复采动回采巷道失稳机理与控制技术

戊9-10-22290工作面为平煤六矿三水平二采区的孤岛工作面,风巷外段在采掘服务期间将会受到上覆戊8及下伏五矿己组回采影响,采掘时空关系异常复杂。目的为探讨多煤层重复采动回采巷道失稳机理与控制技术,方法基于采掘工作面应力时-空演化关系,提出平煤六矿戊9-10-22290工作面风巷外段全生命周期内的围岩控制方法,并进行现场工程应用。结果结果表明:上覆近距离煤层开采后,巷道顶板出现拉剪破坏;本煤层和下伏煤层回采过程中,巷道将逐段受到超前支承压力作用;根据巷道围岩所处的扰动时-空过程和高应力环境,提出“高预应力高强锚杆+锚索+深孔爆破卸压”的抗压-让压-卸压相结合的综合围岩控制技术。现场工业性试验表明,巷道服务期间两帮最大变形量为347 mm,顶板下沉和底板鼓起均在可控范围内,能够满足矿井安全生产需求,取得较好的技术和经济效益,结论研究结果可为类似条件下的回采巷道围岩控制提供参考。

多因素影响下巷道围岩稳定性分析及优化设计研究

针对深部煤层巷道矿压显现剧烈且巷道变形难以控制的问题,基于Kastner公式对巷道高宽比、侧压系数、埋深、断面形状、围岩强度5种影响巷道围岩稳定性的因素展开正交数值模拟实验,通过方差和直观分析图法研究了各因素对巷道变形破坏的敏感性。采用平面弹性复变函数理论分析了不同侧压系数与巷道高宽比下椭圆和矩形巷道围岩的应力分布规律,对椭圆形和矩形巷道宽高比和形状进行了优化设计。研究结果表明:围岩强度与侧压系数是影响巷道围岩稳定性的主要因素,埋深、断面形状、巷道高宽比为次要因素;椭圆形巷道在等轴应力比下围岩应力差值最小;矩形巷道宽度为5 m、高宽比为0.6左右时,应力集中程度较小;针对矩形巷道应力快速增高区,在考虑承压特性和断面利用率的基础上设计了圆角矩形优化巷道,确立了圆角半径的计算公式,通过数值模拟验证了其良好的性能。

深部极松软围岩沿空巷道稳定性控制及应用

针对深部高应力作用下极松软围岩变形量大、破碎程度高、巷道难支护等问题,以丁集煤矿1232(3)沿空巷道为工程背景,采用数值模拟、现场监测和井下试验相结合的方法,对深部高应力极松软围岩沿空巷道破坏特征及阶段性控制原理和技术进行研究。结果表明:随着距巷道迎头距离的不断增大,巷道两帮应力的不对称性逐渐增大,实体煤侧应力峰值为37.18 MPa大于煤柱侧35.21 MPa,1242(3)终采线50 m范围内存在应力集中,最大达33 MPa,巷道围岩塑性区发育程度为煤柱帮大于实体煤帮大于顶底板;从巷道掘进过程中所经历的复杂围岩变化过程,将全巷道划分为5种典型的围岩变化阶段来分析围岩变形破坏特征和破坏机理,揭示了在高应力作用下深部软岩沿空巷道围岩变形量大,在空间上呈现出明显的区域性和非对称性的特征;基于巷道初步设计方案和围岩变形破坏特征,及时有效的调整支护方案,对巷道进行分段式、非对称、区域化综合治理,形成深部软岩巷道围岩控制长效机制,为同类型深部软岩巷道地压治理提供了理论和技术支撑。

三向非等压应力场下围岩主应力差与塑性区分布关系研究

首先,以弹性理论为基础推导出考虑巷道轴向应力影响的主应力差解析式,通过变化水平侧压比、轴向侧压比研究完全弹性条件时不同应力场下主应力差分布形态演化规律。其次,推导出考虑轴向应力作用的围岩塑性区近似解,研究不同应力环境下围岩的塑性区形态演化规律。最后,对比分析主应力差及塑性区形态特征,研究二者分布形态的对应关系,并通过数值模拟验证理论分析的正确性。研究结果表明:在弹性理论下,三向应力场条件的主应力差值分布会呈现圆形、椭圆形、蝶形3种形态的演化规律;在考虑巷道塑性破坏的情况下,主应力差值在σx、σz较小一侧形成峰值壳,在较大一侧形成卸压壳。在不同水平侧压比及轴向侧压比情况下,围岩塑性区形态会呈现圆形—椭圆形、椭圆形—蝶形、蝶形恶性扩展3个阶段的演化过程。巷道主应力差的分布形态在一定程度上可以反映塑性区形态,主应力差和塑性区在相同应力条件下的形态特征具有逐一对应关系,且二者形态在很大程度上由水平侧压比决定,轴向侧压比对塑性区形态影响较小。160206回风巷在偏转式主应力差集中区形成非对称异化特征。本文基于分析及现场破坏情况提出的联合协同支护技术在现场应用效果较好。

高地应力缓斜半煤岩巷道断面形状优化研究

为了优化高地应力缓斜半煤岩巷道的断面形状,以东欢坨矿3018工作面运道为工程背景展开研究。通过复变函数理论推导得出了倾斜煤层中不同断面形状的应力解析解,然后运用FLAC3D数值模拟求解了不同断面形状巷道的应力集中和塑性区情况,并以此为基础确定了巷道最优断面形状,最后结合现场工业性试验对研究结果的可靠性进行了验证。研究结果表明:高地应力作用下缓斜半煤岩巷道破坏呈现非对称形式;不管断面形状如何,巷道均在左、右两底角处呈现高应力集中,且应力集中程度矩形>梯形>直墙拱形;直墙拱形巷道稳定性最佳,梯形巷道次之,矩形稳定性最差,确定直墙拱形为最终巷道断面形状;现场巷道表面位移量监测结果表明,直墙拱形巷道更能满足现场安全生产要求。

近距离煤层联采巷道交错布置及支护技术研究

为解决近距离煤层联合开采时采出率低、安全性差等问题,探究巷道交错布置方式及下煤层巷道支护技术在近距离煤层联合开采中的应用,以山西晋保煤矿12#、13#煤层地质条件为研究背景,采用理论分析与FLAC3D数值模拟的研究方法,研究了巷道采用交错布置时下煤层巷道的围岩变形与矿压变化,得到巷道交错式布置时上下煤层巷道的水平错距应大于7.98 m。通过数值模拟分析矿方原始支护方案与新支护方案下煤层巷道顶板的垂直位移变化规律,确定对下煤层巷道进行锚网索联合支护的分区支护方案。结合现场实测结果表明:下煤层巷道围岩变形处于可控范围内,交错式巷道布置方式以及巷道分区支护方案较为合理,能够保证工作面的安全生产,可以为类似地质条件下近距离煤层的开挖提供借鉴。

深部顶板夹煤层巷道变形破坏分析及其控制

为了探究深部顶板夹煤层软岩巷道大变形破坏问题,以平煤六矿三水平戊二胶带运输巷为工程背景,开展夹煤层巷道围岩破坏分析及控制对策的研究。首先,构建原支护体系组合拱力学模型,推导出直墙半圆拱形巷道稳定判别式;其次,提出“锚网索-梁-注浆-组合砂浆锚索”联合返修控制对策,即沿戊8煤层顶板进行巷道扩刷,采用锚网索、梯子梁完成基本支护,对围岩进行深浅孔注浆加固、顶板及两帮关键部位布置组合砂浆锚索等加强支护,并通过数值模拟分析返修前后应力、位移场分布特征;最后,开展工业性试验,并监测矿压。结果表明:两帮及顶底板最大收敛量分别为93、112 mm,后期变形速率均低于1 mm/d,围岩变形得到有效控制,返修效果良好。

托顶煤切顶留巷围岩控制技术研究

为了解决托顶煤巷道围岩变形难以控制的问题,运用理论分析、离散元数值模拟及现场工业试验相结合的方法对义棠煤业100602工作面切顶成巷围岩控制技术进行研究,分析了不同切顶高度、采高对留巷围岩变形影响规律。研究发现,适当增加切顶高度并降低采高有利于巷道围岩稳定,并确定开采技术参数为切顶高度24 m、采高6 m。现场监测结果显示,在合理的支护策略及开采工艺参数下,托顶煤切顶留巷围岩变形控制效果良好。

坚硬顶板切顶卸压技术对巷道围岩变形规律影响

针对特厚煤层坚硬顶板、宽煤柱条件下临空巷道面临的高围岩应力、大变形等问题,以老石旦煤矿16403综放工作面为工程研究背景,从宽煤柱顶板侧向破断结构角度对临空巷道大变形的影响因素进行了理论分析,采用数值模拟方法研究了对16402运输巷实施不同切顶卸压方案时,临近采空区的16403回风巷侧向顶板采动应力传递规律,并在现场施工水力压裂钻孔进行切顶卸压,实现临空巷道围岩变形控制。研究结果表明:“低位坚硬岩层悬臂梁+高位坚硬岩层砌体梁”破断结构是特厚煤层宽煤柱临空巷道大变形的主要原因,可采用切顶卸压技术破坏宽煤柱顶板侧向破断结构来控制临空巷道围岩大变形;切顶角变化可使关键块B长度发生改变,切顶角越大,则关键块B长度越小,临空侧顶板载荷向煤柱传递的程度越弱,临空巷道围岩承受的采动应力越小,切顶角为100°时临空巷道围岩垂直应力与变形量最小;在16402运输巷以切顶角100°施工水力压裂钻孔后,16403回风巷顶底板变形量较未实施切顶卸压的16402回风巷减小86.5%,两帮变形量减小87.1%,临空巷道围岩稳定性得到极大提高。

巷道围岩连锁冲击破坏机理及稳定控制方法研究

利用虚拟交界面将巷道围岩整体结构分成若干岩体单元和弹性单元,建立巷道围岩连锁冲击破坏理论及其力学结构模型,分析了不同静载、动载组合巷道围岩连锁破坏形式,建立了连锁破坏的力学方程和能量方程,揭示了巷道围岩储能结构、阻力结构在冲击启动和破坏过程中的作用和影响机制。研究表明,冲击地压是动力扰动诱发煤岩体内部弹性能突然释放的结果,其中煤岩体储能结构是冲击破坏的内因和动力源泉,动载诱发局部岩体破坏和能量连续释放;煤岩体冲击破坏时,其整体结构转变为向巷道自由空间运动的多滑块(岩体单元)结构,各滑块间存在相对运动、挤压以及弹性单元触发产生的冲击力,使各岩体单元的速度和加速度均处在动态变化当中;巷道围岩防冲控制的有效思路是调整巷道围岩整体结构,合理分布储能结构和冲击阻力结构,主动破坏能量持续解锁所需的弹性单元,使巷道周边围岩由储能结构转变为阻力结构区域。

瑶渠煤矿大巷间煤柱尺寸确定及支护优化

为研究大巷过剥蚀区时大巷间煤柱合理尺寸及围岩稳定性,以瑶渠煤矿西采区Ⅱ回风大巷为研究对象,采用理论分析、数值模拟等研究方法,建立了煤柱尺寸计算模型,揭示了煤柱在8 m、10 m、12 m、14 m条件下巷道围岩应力、位移及塑性区的分布规律,确定了过剥蚀区大巷间煤柱的合理尺寸,并优化了西采区Ⅱ回风大巷的支护参数。研究结果表明,瑶渠煤矿西采区Ⅱ回风大巷与辅运大巷之间煤柱尺寸由14 m减小至8 m时,巷道围岩内的垂直应力由1.381 MPa增加至1.465 MPa、最大位移量增加了12.52%,塑性区逐渐贯通煤柱。当煤柱尺寸为10 m时,煤柱塑性区处于贯通的临界区域,煤柱内部具有一定的弹性核区域,且煤柱尺寸大于理论计算的9.23 m,能够满足巷道围岩的稳定性。综合考虑,确定煤柱最小合理尺寸为10 m。对10 m煤柱尺寸下西采区Ⅱ回风大巷进行支护优化,采用帮部3根锚杆支护后巷道围岩应力、位移和塑性区均显著改善,保证了巷道围岩的稳定性。

高瓦斯大断面煤巷智能快掘条件下围岩控制研究

针对高河煤矿高瓦斯大断面煤巷智能快掘条件下的围岩控制问题,根据悬吊理论、普氏理论对E2312进风顺槽锚杆、锚索支护参数进行理论计算,初步确定了部分参数,采用数值模拟方法对智能快掘巷道围岩控制效果进行模拟分析,揭示锚杆、锚索协同锚固效应及其双层锚固平衡拱结构形成机理,并确定快掘条件下的最终支护参数。通过对不同支护参数和掘进速度分别制定了多组数值模拟方案,对比分析巷道围岩锚固效应、塑性区发育范围以及顶板下沉量和两帮移近量变化曲线,结合现场工程应用综合分析得出,在一定范围内提高掘进速度的同时,结合对支护参数的优化,更加有利于巷道的围岩稳定控制。

双掘两采留巷围岩应力演化特征及控制技术研究

为解决厚煤层双掘两采留巷围岩稳定性差、长期维护困难等技术难题,以园子沟煤矿1012007综放工作面为工程背景,采用理论分析、数值模拟以及现场实践分析了双巷掘进、一次采动、二次采动期间留巷围岩应力演化特征与塑性区发育规律,得到了留巷在一次采动期间表现出非对称应力演化特征与围岩塑性区非对称发育规律相一致,并提出了“长短锚杆索梯次支护+帮顶M型钢带整体支护+弱结构卸压”组合支护技术,最后成功应用于现场实践。

高水平应力巷道宽高比对围岩变形影响研究

为研究高水平应力巷道宽高比对围岩变形的影响,以某矿42103工作面为研究背景,利用FLAC~(3D)软件,模拟巷道宽高比对围岩应力状态、剪切破坏程度和位移量变化的作用。模拟结果表明,高水平应力作用下,巷道宽高比越大,围岩应力集中程度越小且不容易出现拉应力,分布更为合理,顶板剪切应变集中范围更小;剪切应变较高区域主要集中于两顶角位置,相对孤立,对顶板的剪切效应较低;顶板位移随宽高比变化不敏感,而两帮的位移随着宽高比的增加而逐渐减小,减小的幅度比较大。现场应用后,巷道围岩没有发生明显变形和离层,稳定性程度大大增强。