Mechanism of principal stress rotation and deformation failure behavior induced by excavation in roadways

The failure modes of rock after roadway excavation are diverse and complex.A comprehensive investigation of the internal stress field and the rotation behavior of the stress axis in roadways is essential for elucidating the mechanism of roadway failure.This study aimed to examine the spatial relationship between roadways and stress fields.The law of stress axis rotation under three-dimensional(3D)stress has been extensively studied.A stress model of roadways in the spatial stress field was established,and the far-field stress state at different spatial positions of the roadways was analyzed.A mechanical model of roadways under a 3D stress state was established using far-field stress solutions as boundary conditions.The distribution of principal stressesσ1,σ2 andσ3 around the roadways and the variation of the stress principal axis were solved.It was found that the stability boundary of the stress principal axis exhibits hysteresis when compared with that of the principal stress magnitudes.A numerical analysis model for spatial roadways was established to validate the distribution of principal stress and the mechanism of principal axis rotation.Research has demonstrated that the stress axis undergoes varying degrees of spatial rotation in different orientations and radial depths.Based on the distribution of principal stress and the rotation law of the stress principal axis,the entire evolution mechanism of the two stress adjustments to form the final failure form after roadway excavation has been revealed.The on-site detection results also corroborate the findings presented in this paper.The results provide a basis for the analysis of the failure mechanism under a 3D stress state.

Failure mechanisms of roadways with non-coplanar axial direction and stress space:True triaxial test and mechanical analysis

The axial direction of a roadway often forms a certain spatial angle with the in-situ stress field.Variations in the spatial angles can lead to differences in the stress environment in which the roadway is exposed.Different forms of failure characteristics occur in the roadway.In order to study the failure mechanism with different spatial characteristics,rock-like material specimens with holes in 9 different horizontal and vertical angles were designed.The true triaxial test system was used to carry out the test with the same loading path.The results show that the horizontal angle a and vertical angle β have a significant effect on the specimen strength,specimen rupture angle,and the form of spalling failure in the hole.The spatial angle leads to the formation of asymmetric heterotype V-notches in both sides within the hole.The asymmetry is evident in both the depth and extent of spalling.The strength of the specimen increases and then decreases with increasing vertical angle β.The rupture angle increases and then decreases with increasing horizontal angle a and increases with the increase of the vertical angle β.The stress analytical model of the specimen under three-dimensional compression was established.The distribution of principal stresses around the holes was theoretically analyzed.It is found that the presence of spatial angle changes the distribution of principal stresses around the hole from symmetric to asymmetric distribution.The shift of the principal stresses is responsible for the change from a V-notch to a heterotype V-notch.

Theory,technology and application of grouted bolting in soft rock roadways of deep coal mines

The grouted bolt,combining rock bolting with grouting techniques,provides an effective solution for controlling the surrounding rock in deep soft rock and fractured roadways.It has been extensively applied in numerous deep mining areas characterized by soft rock roadways,where it has demonstrated remarkable control results.This article systematically explores the evolution of grouted bolting,covering its theoretical foundations,design methods,materials,construction processes,monitoring measures,and methods for assessing its effectiveness.The overview encompassed several key elements,delving into anchoring theory and grouting reinforcement theory.The new principle of high pretensioned high-pressure splitting grouted bolting collaborative active control is introduced.A fresh method for dynamic information design is also highlighted.The discussion touches on both conventional grouting rock bolts and cable bolts,as well as innovative grouted rock bolts and cables characterized by their high pretension,strength,and sealing hole pressure.An examination of the merits and demerits of standard inorganic and organic grouting materials versus the new inorganic–organic composite materials,including their specific application conditions,was conducted.Additionally,the article presents various methods and instruments to assess the support effect of grouting rock bolts,cable bolts,and grouting reinforcement.Furthermore,it provides a foundation for understanding the factors influencing decisions on grouted bolting timing,the sequence of grouting,the pressure applied,the volume of grout used,and the strategic arrangement of grouted rock bolts and cable bolts.The application of the high pretensioned high-pressure splitting grouted bolting collaborative control technology in a typical kilometer-deep soft rock mine in China—the soft coal seam and soft rock roadway in the Kouzidong coal mine,Huainan coal mining area,was introduced.Finally,the existing problems in grouted bolting control technology for deep soft rock roadways are analyzed,and the future development trend of grouted bolting control technology is anticipated.

The influence of the disturbing effect of roadways through faults on the faults' stability and slip characteristics

In order to mitigate the risk of geological disasters induced by fault activation when roadways intersect reverse faults in coal mining,this paper uses a combination of mechanical models with PFC2D software.A mechanical model is introduced to represent various fault angles,followed by a series of PFC2D loading and unloading tests to validate the model and investigate fault instability and crack propagation under different excavation rates and angles.The results show that(1)the theoretical fault model,impacted by roadway advancing,shows a linear reduction in horizontal stress at a rate of-2.01 MPa/m,while vertical stress increases linearly at 4.02 MPa/m.(2)Atfield excavation speeds of 2.4,4.8,7.2,and 9.6 m/day,the vertical loading rates for the model are 2.23,4.47,6.70,and 8.93 Pa/s,respectively.(3)Roadway advancement primarily causes tensile-compressive failures in front of the roadway,with a decrease in tensile cracks as the stress rate increases.(4)An increase in the fault angle leads to denser cracking on the fault plane,with negligible cracking near the fault itself.The dominant crack orientation is approximately 90°,aligned with the vertical stress.

矿井巡检机器人复杂斜巷通过性能优化

为提高移动机器人在矿井巷道等复杂环境中的越障稳定性,通过理论分析与RecurDyn仿真试验,研究并提出了一种分析和优化摆臂履带式巡检机器人坡道越障能力和越障稳定性的方法。研究结果表明:坡度对所涉及的巡检机器人最大越障高度和稳定性均有较大影响,在坡度角为(0~35)°工况下,随坡度的增加理论最大越障高度从349mm逐渐减小至221mm,且当坡度角大于30°时,机器人在越障中易处于不稳定状态,故在越障控制时须考虑稳定性因素的影响。该结论可为所涉及巡检机器人的设计和自主越障控制提供理论依据。

底板梳状定向长钻孔技术在淮南矿区瓦斯区域治理应用研究

针对安徽淮南矿区煤巷条带瓦斯区域治理时穿层钻孔量大、施工周期长,以及顺层钻孔一次性成孔难度大、孔内事故频发等难题,提出在张集煤矿采用底板梳状定向长钻孔预抽煤巷条带瓦斯的技术方案。在施工中总结了入煤角度控制、硬岩开分支、飞管护孔等关键技术,形成了一套完善的梳状孔施工工艺,保证了钻孔主孔成孔深度和分支孔见煤率。试验期间,施工钻孔主孔深度均大于400 m,分支孔接力掩护长度均大于300 m。钻孔成孔明显得到改善,干管瓦斯抽采浓度达到60%以上,抽采纯量达到3.5 m^(3)/min,同时节省了施工成本,为淮南矿区的瓦斯区域治理提供了新的方案。

上分层遗留煤柱下方沿空巷道煤柱宽度优化设计

为提高煤柱稳定性和煤炭资源回收率,本文以杨村煤矿3332-2工作面为例,采用FLAC^(3D)数值模拟方法分析了巷道围岩应力和变形规律。结果表明:随着煤柱宽度的增加,巷道左侧峰值的应力集中程度明显增加,右侧峰值的应力集中程度略微降低;巷道顶部和右帮变形量减少,左帮变形量增加,底部变形量变化不大。综合考虑,随煤柱宽度改变,巷道应力与变形虽然有所变化,但均在可接受范围内,因此,3332-2运顺采用4m宽煤柱为宜。

基于地质雷达的巷道松动圈探测图像优化分析及支护改进

以河北中关铁矿井下巷道为工程背景,开展松动圈探测及图像处理优化分析及支护改进。首先依据雷达探测原理,提出了针对金属矿山井下巷道的松动圈探测方案,并优化了雷达探测图像处理方法;然后对探测结果进行了详细分析,讨论了不同岩性及不同埋深水平对巷道松动圈范围的影响。研究结果表明:采用探地雷达可以有效测得井下巷道松动圈范围,中关铁矿井下巷道松动圈分布复杂多变,巷道岩性越差,埋深越大,松动圈范围越大,反之亦然。依据松动圈范围和锚杆作用机理,在岩性较差的围岩段,松动圈厚度范围超过2.5 m,应优化支护方案采用长度更长的锚杆并加密锚杆间距。

近距离煤层采空区下回采巷道快速掘进技术研究

针对上榆泉煤矿近距离煤层群赋存情况,考虑I031005回采巷道上覆9#煤层采空区的影响,采用现场调研、数值模拟以及理论分析相结合的方法,在保证回采巷道围岩稳定的情况下,提出了“锚杆支护参数优化+设备改进+工艺流程优化”的快速掘进综合技术体系。研究结果表明:基于层次分析法建立下煤层回采巷道快速掘进影响因素综合评价体系,明确影响巷道掘进速度的重要因素巷道地质条件和支护工艺;10^(#)煤层巷道基本不受9^(#)煤层遗留煤柱集中应力影响,且围岩完整性好,强度高,适当增加单根锚杆强度,减小锚杆间排距不影响回采巷道围岩稳定,锚杆合理间排距为1500 mm×1200 mm,锚杆长度为1800 mm;优化支护参数后支护时间显著降低,巷道单排支护时间由30 min降低至22 min,提高单次掘锚循环进尺提高至1.2 m;提出滑移架与截割装置相连的结构,优化循环作业方式,使掘锚同步作业,掘支平行作业率可增加42.7%;巷道月平均进尺可由750 m增至1080 m,增幅44%。研究结果可为类似条件矿井回采巷道快速掘进提供借鉴。

厚煤层采准巷道布置及围岩稳定性研究

为了解厚煤层采准巷道布置形式对围岩稳定性的影响,文章通过数值模拟,分析了巷道沿顶掘进、布置在煤层中间和沿底掘进三种不同布置形式下围岩的变形情况,并监测巷道围岩的变形数据。研究发现,巷道沿底掘进时,整体变形较为均匀,顶板、帮部和底板位移梯度均较小,有利于增强围岩的稳定性。

一种煤矿矩形巷道智能支护设计专家系统

针对煤矿矩形巷道支护参数设计问题,采用模糊数学对煤巷围岩稳定性的类别进行分析。选择顶板岩石单轴抗压强度、底板岩石单轴抗压强度、煤层单轴抗压强度、巷道埋深、采动影响系数、护巷煤柱宽度、围岩完整程度7个指标作为矩形巷道围岩稳定性分析指标,并根据不同的围岩稳定性类型选用不同的支护形式;采用(内嵌数值模拟软件优化、CAD)支护设计方法进行设计,并进行合理的支护参数计算,通过数据库中的诸多样本判断类似的样本数据以自动选择合理的支护方案。以Visual Studio 2022为开发工具,利用SQL Sever 2019构建了围岩力学参数、支护参数、围岩稳定性等信息巷道信息数据库,采用C#语言进行计算机编程,实现了巷道参数数据库管理、围岩稳定性分类、支护参数智能设计等功能。

深部高应力巷道失稳特征与围岩控制技术研究

鄂尔多斯市中部某煤矿围岩收敛变形现象严重,原始支护技术无法有效控制围岩失稳,基于现场实际情况及组合拱理论,提出“增加支护+补强锚杆”的支护方案,通过增加锚固长度和管缝式锚杆间排距,锚杆与围岩形成了良好的自稳结构。利用数值模拟对比分析原始支护与优化支护后的应力场,位移场和塑性区,通过定性与定量相结合的分析方法,结果表明优化支护方案对围岩控制效果良好,应力释放范围小,最大位移量仅为原始支护位移量的0.57倍,塑性区破坏单元减少了85%以上。通过现场监测发现数值模拟结果准确,顶板下沉量减少了50%,帮部收敛量减少了41%,验证了该优化支护方案对深部高应力大断面巷道具有良好的控制作用。

纵轴岩巷掘进机截割部故障分析

主要介绍了纵轴岩巷掘进机截割部的组成和工作原理。通过对截割部结构分析,结合现场经验,总结了一些常出现的故障现象,对其原因进行分析并提出应对措施,可以帮助维修人员快速判断和解决问题,也为截割部的设计提供依据。

三元石窟煤矿顶板淋水区域注浆封堵与锚索支护技术

传统支护技术在三元石窟煤业软岩淋水巷道中的应用效果不佳,采用注浆封堵与锚索支护工艺对巷道顶板支护技术进行改进。依托FLAC 3D数值模拟软件分析了1、5、10 MPa注浆压力与300、400、500 mm封孔长度条件下的锚索孔围岩变形量与封孔段围岩最大主应力的分布特征。在井下开展拉拔试验测试支护体力学性能,开展工业试验验证。结果表明:锚索孔围岩位移量随浆液压力的提升而增加。软弱粉砂岩条件下的注浆压力不宜大于5 MPa。封孔长度应以围岩的裂隙发育位置作为考量标准,当裂隙发育位置位于围岩深部区域时,封孔长度应相对较长,反之亦然。封孔长度的增加有利于提升锚索的抗拉强度。在现场实施注浆封堵与锚索支护工艺的50 d后,围岩变形基本达到稳定,且淋水现象大幅降低。

大断面强动压影响沿空巷道围岩控制技术研究

沿空留巷相较于常规留煤柱开挖巷道方式具有较好的技术和经济优势,沿空留巷技术应用过程中巷旁充填体参数设置对巷道稳定性具有重要作用。通过实验室试验方法分析了超高水材料含水率对试件强度的影响规律,进而建立了8107工作面数值模型;通过数值模拟方法分析了不同参数条件下巷旁充填体变形情况,确定选择合理的巷旁充填体参数后,制定了8107工作面回采巷道的最终围岩控制方案。经现场实践检验,巷旁充填体、煤柱帮、顶板、底板的最大变形量分别为223、 205、 168、 40 mm;巷道围岩变形量满足作业规程的相关要求。研究成果可为相似条件下巷道围岩控制提供一定的借鉴。

近距离煤层采空区下巷道位置优化及掘进时机研究

为研究近距离煤层采空区下巷道位置优化及掘进时机,以西部A煤矿1W302工作面为研究对象开展研究。通过理论计算分析采空区底板应力分布特征及其破坏范围,以弹性力学、材料力学等为理论基础,计算得出底板破坏影响范围。利用数值模拟软件,分析上煤层回采后采空区底板岩层状态,对下煤层顺槽不同掘进位置对围岩造成的影响进行模拟,并对1W302工作面现有支护的可靠性进行了分析。通过分步回采模拟上煤层不同回采长度对下煤层巷道顶板下沉量的影响,分析得出下煤层巷道顶板趋于稳定的时间,合理确定巷道掘进的时机。

柠条塔矿二次复用巷道联合维护技术研究与运用

针对沿空留巷二次复用巷道变形严重的问题,以柠条塔煤矿S1212工作面为背景,回采100 m时,二次复用巷道出现严重变形,已影响正规循环作业。科研人员进行现场实勘并分析巷道变形原因,提出起底、挑顶、扩帮联合维护技术和超前密集导向钻孔切顶卸压和底板卸压槽技术改善变形,并进行了现场试验。结果表明,二次复用巷道采用联合维护技术和卸压技术后,巷道变形情况明显得到改善,逐渐恢复正轨循环作业,该技术减少了工作面安全隐患,保障了工作面安全高效回采,可推广实施。

伊犁四矿弱胶结软岩巷道围岩控制技术研究及应用

以新疆伊犁四矿21113工作面为工程背景,通过理论分析、数值模拟以及现场实测等手段,围绕浅埋弱胶结软岩巷道破坏特征及控制技术展开了一系列研究,研究结果表明:伊犁四矿弱胶结软岩巷道围岩变形特点为自稳时间短、应力释放明显,泥岩遇水易软化、出现无征兆冒顶,岩体自重大、顶板出现下沉,支护结构受力不耦合、支护单元破坏等。根据围岩变形特点提出了对巷道围岩及时支护、喷浆封闭、拱形断面、加长支护的联合支护技术,经过现场工业性试验以及观测数据证明,该联合支护方案,能够很好地控制巷道变形,21113上顺槽巷道从开始回采到结束未出现瞬发变形、顶板切落、锚杆(索)断裂及钢带撕裂等情况,巷道变形及维护满足工作面顺槽的使用要求。可为伊犁矿区弱胶结软岩巷道支护设计和施工提供指导作用。

孤岛工作面沿空巷道支护方案优选及应用分析

为实现对孤岛工作面回采巷道围岩的有效控制并提升煤炭资源回采率,以3507工作面回采巷道掘进为工程背景,针对性提出围岩掘进及支护方案,并依据3507工作面现场情况及围岩控制需要优选采用以U型钢支架+柔模墙体为基本支护的小煤柱沿空掘巷方案。工程应用后,3507工作面回采巷道围岩保持稳定,顶板、回采帮、底板、柔模墙体变形量分别控制在98、 95、 61、 24 mm,围岩变形量整体较小,表明采用的支护方案围岩控制效果显著。研究成果可为其他孤岛工作面回采巷道围岩控制提供经验借鉴。

双柳煤矿33(4)23工作面贯通测量设计及应用效果

随着采面长度的增加,巷道贯通测量长度也随之增大,导线长、测点多等因素会导致贯通测量累计误差增大,为此,长距离巷道掘进对贯通测量的质量提出更高要求。以双柳煤矿33(4)23工作面回采巷道贯通测量为工程背景,其导线总长4993.2m,结合现场情况及以往工程测量经验,贯通测量方案设计预先计算贯通误差为土0.258m,现场贯通实测误差为0.387m,估算误差与实测误差均小于预先确定的极限误差土0.500m。实践表明,该测量方案可满足长距离巷道优质贯通需要。