Numerical simulation of airflow distribution in mine tunnels

Based on 3D modelling of typical tunnels in mines, the airflow distribution in a three-center arch-section tunnel is investigated and the influence of air velocity and cross section on airflow distribution in tunnels is studied. The average velocity points were analyzed quantitatively. The results show that the airflow pattern is similar for the three-center arch section under different ventilation velocities and cross sectional areas. The shape of the tunnel cross section and wall are the critical factors influencing the airflow pattern. The average velocity points are mainly close to the tunnel wall. Characteristic equations are developed to describe the average velocity distribution, and provide a theoretical basis for accurately measuring the average velocity in mine tunnels.

Considerations of rock dilation on modeling failure and deformation of hard rocks-a case study of the mine-by test tunnel in Canada

For the compressive stress-induced failure of tunnels at depth, rock fracturing process is often closely associated with the generation of surface parallel fractures in the initial stage, and shear failure is likely to occur in the final process during the formation of shear bands, breakouts or V-shaped notches close to the excavation boundaries. However, the perfectly elastoplastic, strain-softening and elasto-brittle-plastic models cannot reasonably describe the brittle failure of hard rock tunnels under high in-situ stress conditions. These approaches often underestimate the depth of failure and overestimate the lateral extent of failure near the excavation. Based on a practical case of the mine-by test tunnel at an underground research laboratory (URL) in Canada, the influence of rock mass dilation on the depth and extent of failure and deformation is investigated using a calibrated cohesion weakening and frictional strengthening (CWFS) model. It can be found that, when modeling brittle failure of rock masses, the calibrated CWFS model with a constant dilation angle can capture the depth and extent of stress-induced brittle failure in hard rocks at a low confinement if the stress path is correctly represented, as demonstrated by the failure shape observed in the tunnel. However, using a constant dilation angle cannot simulate the nonlinear deformation behavior near the excavation boundary accurately because the dependence of rock mass dilation on confinement and plastic shear strain is not considered. It is illustrated from the numerical simulations that the proposed plastic shear strain and confinement-dependent dilation angle model in combination with the calibrated CWFS model implemented in FLAC can reasonably reveal both rock mass failure and displacement distribution in vicinity of the excavation simultaneously. The simulation results are in good agreement with the field observations and displacement measurement data.

Investigation of 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 mines.Ensuring of stability for soft-rock tunnels is an important task for deep coal mines located in high in situ stress conditions.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 by using 3DEC software to simulate the stress conditions around a tunnel located under high in situ stress conditions in a coal rock mass in China.Analyses were conducted for several tunnel shapes and rock support patterns.Results obtained for the distribution of failure zones,and stress and displacement felds around the tunnel were compared to select the best tunnel shape and support pattern to achieve the optimum stability conditions.

Research on sustenance of soft rock tunnel in Hongmiao Mine of Pingzhuang Mine Area

The return airway tunnel of bank 6 is an important tunnel for air return and auxiliary transportation.While under construction,the tunnel was seriously deformed, and the bottom was heavily squeezed.When completed,the bottom was smoothed out several times and a lot of maintenance were done.But about half year later,the tunnel collapsed.To counter the problems mentioned above,we systematically expounded our ideas and designed for solving the problem of the sustenance of the return airway tunnel of section 6.

Study and practice of the controlling technique on heat-harm during the tunneling in Zhaolou mine

This paper proposes the cooling system type and cooling equipment type which are deep mine with high temperature during the construction,and presents auxiliary cooling measures making up duct temperature rise since compression and heat transfer temperature rise. The cooling system designed against Zhaolou mine's ground temperature and weather conditions,with its sprinkler room handling an average temperature difference up to 19.5～23.8 ℃,and the average enthalpy difference could reach 48.4～60.7 kJ/kg. At the same time,it gets a series of basic data used for mine construction during the cooling system design and equipment selection according to the measured results; using the analysis software Matlab,it obtains the change relations between the temperature of sprinkler room and fan export supply air temperature,wind casing temperature rise and fan export supply air temperature,working face temperature and supply air temperature,used for the mine cooling which has the similar conditions.

Performance analysis of wireless local area networks(WLAN) in a coal-mine tunnel environment

In order to establish an effective wireless communication system in an underground coal-mine environment, the propagation of radio waves through a rectangular-like mine tunnel was investigated by jointly, considering both the dielectric constant and the reflectance of a mine tunnel. By combining free space and modified waveguide propagation models, we propose a new hybrid propagation model based on ray tracing. Simulation results have shown the effectiveness of establishing a wireless Local Area Network (LAN) in this coal-mine environment. The results of this research will be very useful as a guide in the design and development of tunnel wireless LAN systems.

Engineering Geological Classification of Surrounding Rock Stability in Coal Mine Tunnels and Its Engineering Applications

The stability type and spatial distribution of surrounding rock are an important basis for the layout of hae tunuels and the selection of support patterns in a mine design. Based on a lot of investigations and testing studies,a new engineering geological classification scheme of surrounding rock stability is put forward,which is easy to be applied,and reliable verified by examples. According to the classification system,the spatial divisions of surrounding rock stability can be delineated in an exploration progamme, providing relevant engineering geological informations for mine designers to prevent them from making the uurealistic tunnel layout and support

采空塌陷区隧道病害机理与防控研究现状与展望

我国是煤炭生产大国,煤炭开采造成了大量采空塌陷。随着公路铁路网不断加密,在山西等采煤大省,越来越多的交通隧道不得不穿越煤矿采空塌陷区。采空塌陷区岩层破坏剧烈、变形量大且持续时间长,是隧道工程建设与运营的重大安全隐患,系统研究采空塌陷区隧道灾变机理与防控技术是隧道工程建设与运营安全的重要保障。通过分析文献报道的工程案例,总结了采空塌陷区隧道的主要病害类型及其灾变机理,回顾了塌陷区采动岩体长期变形预测方法与隧道灾变预测方法,介绍了塌陷区采动岩体变形控制方法与穿越采空区隧道围岩处治方法。在此基础上,分析了采空塌陷区隧道灾变与防控技术研究中存在的突出问题,并对亟待研究的方向进行了展望。

基于微震监测的深部下分层巷道掘进围岩破坏特征研究

针对分层采场内掘进巷道利用微震有效实施围岩破坏监测的难题,以淮南矿区潘二煤矿12221下分层掘进工作面为工程背景,开展了下分层开采巷道掘进微震监测研究,提出了相应的随掘微震监测方法,分析了分层开采条件下巷道掘进围岩破坏特征。结果表明,以所提出的等距交错往复式随掘方法搭建微震监测系统能够实现对现场破裂信号的有效拾取,巷道掘进过程中微震事件以地质结构为界线呈现阶段性分布特征,也验证了方法的合理性;同时,受上分层采动影响下的巷道围岩破坏呈现蝴蝶形分布(10 m),在掘进巷道两帮围岩的肩颈位置呈现出较大范围的破坏(15~20 m)。研究结果可望为微震监测技术应用及巷道围岩支护提供一定指导。

HSP超前探测技术在煤矿TBM掘进巷道中的应用研究

随着全断面掘进机TBM(Tunnel Boring Machine)逐渐应用于煤矿岩巷掘进,对不良地质构造进行超前准确快速预测的需求日益迫切。通过对主动源地震波超前探测方法的特点和TBM破岩震源超前探测技术的适用性进行分析,结合煤矿巷道地质和生产条件,提出了适用于煤矿巷道TBM掘进的HSP超前探测方法。以河南平顶山首山一矿TBM掘进底板瓦斯治理巷道为工程背景,选用防爆硬件一体化设计的探测仪器在煤矿巷道中进行应用。构建了空间型观测方式对煤矿巷道近水平煤线进行探测,优化了双护盾TBM掘进巷道狭小空间检波器阵列式布置参数;基于时频分析、互相关干涉处理、反射与散射联合反演等方法处理原始信号并进行探测结果成像。研究表明:采用空间型观测方式可实现与巷道小角度斜交煤线的识别,设计震源与首检波器间距离为15 m时最优。通过时频分析提取有效信号,利用互相关干涉法获取虚拟震源道和反射特征曲线,并结合反射与散射联合反演成像得到探测区域地层反射能量分布图,能够较准确地推测得到围岩存在的不良地质构造。通过比较现场开挖揭露情况与探测结果发现两者吻合度较高,表明HSP超前探测方法可实现掘进工作面前方100 m范围内超前无损地质预测,有助于提高煤矿岩巷TBM掘进速度。

井下巷道新型可见光通信光源布局方法

目的针对井下巷道可见光通信信号差异大,导致接收端信号误差增大的问题,方法提出一种井下巷道新型可见光通信光源布局方法,并同现有光源布局方法进行对比,从光照度、接收功率、信噪比三个方面评估两种布局方法的系统性能。引入照度均匀度(IU)、功率标准偏差(STD)和信噪比的变化系数(CV)评估系统的整体性能。结果通过仿真实验,分析不同半功率角对本文布局方法系统性能的影响,从而得出半功率角的最优取值,为50°~70°。当半功率角为70°时,与现有光源布局方法比较,本文布局方法的光照度均匀度由0.758降至0.407,降低了46.3%,且最小光照度与最大光照度之间差异更小,光照度分布更均匀;功率标准偏差由0.97降至0.42,降低了56.7%,且降低了功率波动,接收功率分布更均匀;信噪比变化系数由0.0137下降到0.0072,降低了47.7%,信号分布均匀性更高。结论提出的光源布局方法整体性能优于现有方法的,为井下巷道的光源布局提供了新的解决方案。

近距离煤层下行采动应力场分布规律与巷道合理位置研究

上层位近距离煤层开采后,形成的残留煤柱和采空区将会影响下层位的巷道布置。以新柳矿231101工作面为工程背景,采用理论分析和数值模拟的综合研究手段,研究和分析了上煤层开采后采动应力场的应力演化规律,对下层煤巷道非对称变形破坏机理进行深入探究,从而得出下层煤巷道合理布置位置。研究结果表明:①上覆煤层开采改变巷道所处位置的主应力大小、主应力比值以及应力偏转角、应力矢量的变化是导致巷道呈非对称破坏的主要原因。②巷道在距离煤柱中心11 m处,巷道围岩最大主应力达到14.43 MPa,主应力比值为2.74,应力偏转角为52.33°,此时巷道处于较差的应力环境中,致使围岩产生蝶形破坏且蝶叶旋转至巷道顶板右侧,巷道顶板右侧易发生冒顶事故。③为使巷道处于相对稳定区域,依据3个主要影响因素将工作区域划分为4个分区,在考虑煤矿经济与安全因素后建议最佳布置区域为H–IV,主应力偏转角在0°~38°或45°~90°的范围内,通过综合分析对该巷道布置及支护提供合理建议,为类似工程条件提供了借鉴和参考。

正断层错动作用下矿山法隧道受力变形机理的模型试验研究

为研究正断层错动作用下矿山法隧道的受力变形机理,以胶州湾第二海底隧道穿越沧口断裂为工程背景,采用自研的大比尺穿越断层隧道结构破坏加载试验装置,针对设置柔性连接变形缝和变形缝间距对隧道结构抗错断效果的影响,开展几何相似比为1∶40的矿山法隧道穿越倾角70°的正断层错动模型试验,对错动试验过程中的隧道变形、应变分布、围岩接触压力和破坏特性等关键指标进行监测,分析获得了正断层错动作用下隧道变形和力学响应规律。研究结果表明:(1)隧道在正断层错动作用下,呈现纵向拉弯+竖向挤压的受荷模式,在下盘邻近断层面处拱顶部位和上盘邻近断层面处仰拱部位出现脱空区;(2)隧道开裂主要以纵向贯通裂缝为主,近断层面处衬砌还出现了部分斜向裂缝和环向裂缝;(3)节段间的连接形式和节段长度不会根本上改变隧道在断层错动作用下的受荷模式和变形模式,但节段间刚度越小,节段长度越小,结构对于地层强制位错的适应性就更好;(4)相比于刚性连接,节段间的柔性连接吸收了大部分地层强制位错,有效降低衬砌节段的荷载和变形,使结构趋于安全。

深部特厚煤层综放沿空掘巷煤柱优化及巷道支护

为研究深部大采高综放工作面窄煤柱沿空掘巷巷道矿压控制问题,以国能宁煤集团枣泉煤矿2^(-2)特厚煤层130203大采高综放工作面回风巷道为背景,基于实用矿山压力理论,建立了巷道围岩内、外应力场动态结构力学模型,运用理论计算和数值计算针对不同尺寸煤柱煤体应力对比分析,将原留设15 m护巷煤柱缩小至5 m进行了煤柱优化。结果表明:在稳定的内应力场掘巷有利于巷道的稳定性,避免了顶板事故及冲击地压相关灾害的发生,现场5 m小煤柱护巷工程应用中,130203回风巷道小煤柱侧变形量为1050 mm,实体煤帮变形量为400 mm,两帮呈现不对称性变形,底板局部底鼓量为1400 mm;深部特厚煤层综放开采沿空掘巷采用5 m小煤柱护巷方案设计正确,极大改善了巷道围岩的应力环境,整体设计满足生产要求,现场应用良好。130203工作面小煤柱沿空掘巷技术成功应用,为矿井开采提供了可靠的科学依据。

基于移动激光扫描的地铁隧道渗漏水定位及快速检测方法

渗漏水是地铁隧道最主要的病害之一,也会导致其他结构病害,开展地铁隧道渗漏水病害检测方法研究具有重要意义。本文聚焦于地铁隧道渗漏水问题,提出了一种基于移动激光扫描点云数据的渗漏水定位及检测方法。首先,结合移动激光扫描检测方法,开展了隧道精确定位方法研究。然后,对YOLOv7模型进行了改进,引入了ConvNeXt网络和CBAM模块以使模型更好地捕获多尺度、多抽象级别的特征,增强对渗漏水关键特征的关注;使用GIoU Loss损失函数,使模型能够更好地处理不完整渗漏水框;预测时使用Soft-NMS加权平均的方法,保留更多的边界框,从而提高检测精度。结合在重庆地铁获取的激光扫描数据构建的盾构法和矿山法隧道渗漏水数据集,验证了本文方法的高效性和稳健性。消融试验表明,本文方法相较于基线模型在不同数据集上均取得了显著的性能提升,在盾构法数据集中,准确率P提升了8.1%,召回率R提升了4%;在矿山法数据集中,准确率P提升了8.6%,召回率R提升了6.8%。同时,与主流目标检测算法,如Faster RCNN(Swin)、Faster RCNN(ConvNeXt)、YOLOv8对比,本文方法在精度和速度方面都表现出优势。最后,本文展示了部分隧道渗漏水的定位与检测结果,以验证本文方法的实用性。

煤矿采矿工程巷道掘进与支护技术策略探讨

巷道掘进与支护是煤矿采矿工程的关键性施工环节,其施工质量关乎于采矿工程建设运营过程的整体安全性。随着煤炭行业安全生产意识和要求的不断提高,人们愈发关注巷道掘进与支护环节的施工质量。基于此,本文在简要阐述采矿工程巷道施工特点的基础上,对掘进与支护施工的主要影响因素进行分析,并分别对掘进施工和支护施工的主要技术和实施要点进行探讨总结,以期为巷道掘进与支护技术的规范化、科学化实践运用提供参考和借鉴,促进煤矿采矿工程巷道掘进与支护施工质量性和安全性的进一步提升。

基于磁流变弹性体动力吸振器的掘进装备振动控制

针对掘进装备在自适应截割控制下的截割部宽减振问题,基于磁流变弹性体的动力吸振技术,提出了一种掘进装备截割部的振动控制方法。首先,以连续采煤机为研究对象,根据动量矩定理,建立了截割部-磁流变弹性体动力吸振器(MREDVA)耦合动力学模型,从理论上分析了MREDVA的减振机理;然后,为保证MREDVA的磁路以及移频特性满足需求,详细阐述了MREDVA的设计流程,提出了一种新的MREDVA结构,对其磁场和移频特性进行了仿真验证;最后,计算了不同截割状态下MREDVA对截割部的振动抑制能力,并建立了半主动控制方法,比较了被动和半主动振动控制方法下MREDVA的振动抑制能力。研究结果表明:对于所选煤层1和煤层2,截割部的振幅衰减分别达到41.53%和49.80%;对于所选煤层3,半主动控制下截割部振幅衰减可以达到45.10%。该方法可以有效降低掘进装备在宽频激励下的振动幅度。

TBM掘进煤矿巷道力学及变形分析

以保安采区8号煤南回风巷为研究对象,基于CVISC蠕变模型,对其TBM掘进过程进行分析,研究不同支护方式下巷道的位移及力学性能变化规律,并将其数值模拟结果与实际监测数据进行对比,以验证数值模拟结果的准确性。结果表明:采用锚索和锚杆对煤矿巷道进行支护能减小其隧道围岩的受力,其中,采用锚索+钢筋网的支护方式效果最优;各工况下的竖向应力均大于其水平应力,煤矿巷道的受力主要以竖向为主,最大应力均出现在围岩的顶部和底部,不同支护方式下围岩发生的位移具有一定的差异性,采用锚索+钢筋网的支护方式产生的位移量最小,煤巷道稳定性较高,未采取支护措施的围岩位移量最大,此时煤矿巷道的稳定性较差,易发生变形。

煤矿岩巷TBM掘进随掘地震信号特征及其应用

随掘地震超前探测技术可实现探掘平行,为巷道快速智能掘进场景下实时、精准地质保障提供了可能。随掘震源产生的是复杂、变频、连续信号,信号特征认知直接影响数据处理与成像精度,而目前针对岩巷全断面掘进机(TBM)随掘地震信号特征的认知仍不清晰,且暂时还没有针对性开展过信号处理与成像研究工作。针对上述问题,以谢桥煤矿瓦斯治理巷TBM随掘地震超前探测试验为例,分析了刀盘先导信号与岩壁接收信号的时间域、频率域及时频域特征:岩巷TBM随掘地震信号中不同振幅能量成分比例呈现金字塔形,但分布随机,不对称程度较高;机械运转信号能量较大,刀盘先导信号强度是岩壁接收信号的200倍左右;频率域变频特征明显;机械运转信号基础频率较低,刀盘先导信号频率成分主要集中在10~80 Hz与150~200 Hz,主频为36.99 Hz,岩壁接收信号频率成分主要集中在50~200 Hz,主频为137.97 Hz;刀盘先导信号较岩壁接收信号时频域能量团分布更为规则,多次震源激发现象明显,能量团之间的差异性特征表明了多次震源激发时振幅能量与持续时间的随机性。利用脉冲化算法与绕射叠加偏移成像方法对岩巷TBM随掘地震信号进行数据处理与成像试验,结果表明:(1)脉冲化等效单炮记录与利用常规震源得到的超前探测单炮记录特征一致性较强,同相轴清晰且连续性较好,可满足现场探测分析需要。(2)对探测范围内岩体情况的超前预报结果与实际揭露情况一致,说明岩巷TBM随掘地震超前探测可提供有效地质保障。

利用退出煤矿建设抽水蓄能电站的施工组织探讨

抽水蓄能电站是目前最经济有效的电力储能及调节方式,对保障电力系统安全、促进风、光等新能源消纳利用有重大作用。煤炭开采造成巨大的地下空间,可作为抽水蓄能电站的储水水库加以利用,将产生良好的社会和环境效益。本文从施工角度出发,探讨了利用退出煤矿建设抽水蓄能电站的可行性。