Instability mechanism of mining roadway passing through fault at different angles in kilometre-deep mine and control measures of roof cutting and NPR cables

The angle α between the fault strike and the axial direction of the roadway produces different damage characteristics. In this paper, the research methodology includes theoretical analyses, numerical simulations and field experiments in the context of the Daqiang coal mine located in Shenyang, China. The stability control countermeasure of "pre-splitting cutting roof + NPR anchor cable"(PSCR-NPR) is simultaneously proposed. According to the different deformation characteristics of the roadway, the faults are innovatively classified into three types, with α of type I being 0°-30°, α of type II being 30°-60°, and α of type III being 60°-90°. The full-cycle stress evolution paths during mining roadway traverses across different types of faults are investigated by numerical simulation. Different pinch angles α lead to high stress concentration areas at different locations in the surrounding rock. The non-uniform stress field formed in the shallow surrounding rock is an important reason for the instability of the roadway. The pre-cracked cut top shifted the high stress region to the deep rock mass and formed a low stress region in the shallow rock mass. The high prestressing NPR anchor cable transforms the non-uniform stress field of the shallow surrounding rock into a uniform stress field. PSCR-NPR is applied in the fault-through roadway of Daqiang mine. The low stress area of the surrounding rock was enlarged by 3-7 times, and the cumulative convergence was reduced by 45%-50%. It provides a reference for the stability control of the deep fault-through mining roadway.

Investigation of a non-explosive directional roof cutting technology for self-formed roadway

Traditional explosives have characteristics of high risk,large vibration,and poor directional fracturing.Consequently,an instantaneous expander with a single crack surface(IESCS),which is a novel nonexplosive directional rock-breaking technique,has been developed.The directional roof-cutting mechanism of the IESCS method,driven by high-pressure gas,was theoretically analyzed.Laboratory experiments and numerical simulations proved the directional slitting effect of the IESCS method to be excellent.Compared with shaped-charge blasting,the charge of IESCS was reduced by 8.9%,but the crack rate increased by 9%in field tests.After IESCS pre-splitting,the roof directionally collapsed along the cutting line,and the gangue filled the goaf.Moreover,the directional roof cutting by the IESCS could decrease roadway stress.The average pressure of hydraulic supports on the cutting side of the roof was 31%lower than that on the non-cutting side of the roof after pre-splitting.After the self-formed roadway constructed by the IESCS was stabilized,the final relative displacement of the roof and floor was 157.3 mm,meeting the required standard of the next working face.Thus,the IESCS was effectively applied to directional roof pre-splitting.The results demonstrate the promising potential of IESCS in the mining and geotechnical fields.

Stability control measures for roof cutting and NPR supporting of mining roadways in fault areas of kilometre-deep coal mine

The study focuses on the stability control measures for mining roadways in fault zones of deep mines,using Daqiang Coal Mine as a case study.The control system under consideration,referred to as"pre-splitting cutting roof+NPR anchor cable"(PSCR-NPR),is subjected to scrutiny through theoretical analysis,numerical modelling,and field trials.Furthermore,a comprehensive analysis is undertaken to evaluate the stability control mechanism of this particular technology.The study provides evidence that the utilization of deep-hole directional energy-concentrated blasting facilitates the attainment of directional roof cutting in roadways.The aforementioned procedure leads to the formation of a uniform structural surface on the roof of the roadway and causes modifications in the surrounding geological formation.The examination of the lateral abutment pressure and shear stress distribution,both prior to and subsequent to roof cutting,indicates that the implementation of pre-splitting techniques leads to a noteworthy reduction in pressure.The proposition of incorporating the safety factor Q for roof cutting height is suggested as a method to augment comprehension of the pressure relief phenomenon in the field of engineering.The analysis of numerical simulation has indicated that the optimal pressure relief effect of a mining roadway in a fault area is attained when the value of Q is 1.8.The NPR anchor cable exhibits noteworthy characteristics,including a high level of prestress,continuous resistance,and substantial deformation.After the excavation of the roadway,a notable reduction in radial stress occurs,leading to the reinstatement of the three-phase stress state in the surrounding rock.This restoration is attributed to the substantial prestress exerted on the radial stress.The termination point of the NPR anchor cable is strategically positioned within a stable rock formation,allowing for the utilization of the mechanical characteristics of the deep stable rock mass.This positioning serves to improve the load-bearing capacity of the surrounding rock.The mining roadway within the fault region of Daqiang Coal Mine is outfitted with the PSCR-NPR technology.The drop in shear stress experienced by the rock surrounding the roadway is estimated to be around 30%,whilst the low-stress region of the mining roadway extends by a factor of approximately 5.5.The magnitude of surface displacement convergence experiences a decrease of approximately 45%-50%.The study’s findings provide useful insights regarding the stable of mining roadway in characterized by fault zones.

Evaluation of roof cutting by directionally single cracking technique in automatic roadway formation for thick coal seam mining

Automatic roadway formation by roof cutting is a sustainable nonpillar mining method that has the potential to increase coal recovery,reduce roadway excavation and improve mining safety.In this method,roof cutting is the key process for stress relief,which significantly affects the stability of the formed roadway.This paper presents a directionally single cracking(DSC)technique for roof cutting with considerations of rock properties.The mechanism of the DSC technique was investi-gated by explicit finite element analyses.The DSC technique and roof cutting parameters were evaluated by discrete element simulation and field experiment.On this basis,the optimized DSC technique was tested in the field.The results indicate that the DSC technique could effectively control the blast-induced stress distribution and crack propagation in the roof rock,thus,achieve directionally single cracking on the roadway roof.The DsC technique for roof cutting with optimized parameters could effectively reduce the deformation and improve the stability of the formed roadway.Field engineering application verified the feasibility and effectiveness of the evaluated DSC technique for roof cutting.

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。

数值模拟对切顶卸压多角度的分析与应用

为了解决坚硬顶板难垮难落,从而造成采空巷道危险性增加的问题,对切顶卸压进行了数值模拟的研究分析。通过利用数值模拟软件FLAC3D对不同切顶角度下的切顶效果进行分析对比,确定出最佳切顶角度为10°。对最佳切顶角度下卸压效果进行分析,发现设计时应综合考量顶板岩性和切顶短臂结构的稳定性,当巷道处于低应力环境时,则更有利于巷道维持稳定性控制。

寺河二号井切顶卸压无煤柱开采技术应用

为了缓解寺河二号井采掘衔接紧张的不利局面,降低巷修成本、消除区段护巷煤柱应力集中、提高煤炭回收率,以97222巷为工程试验对象,结合理论分析、工程类比等方法,对97311回采工作面97222运输顺槽顶板岩性、爆破孔参数、留巷补强参数、挡矸堵漏等进行系统研究。现场矿压监测数据表明:滞后工作面215 m范围外留巷围岩变形趋于稳定,顶底板相对移近量最大值365.12 mm,两帮相对移近量最大值462.14 mm。

深井工作面顶板巷道卸压参数确定及控制技术研究

为解决深井工作面巷道顶板受深部采动应力而诱发的围岩大变形现象,采用理论分析及现场试验等方法,建立了应力拱力学模型并推导得出顶板巷道卸压高度计算公式,确定了某矿17191(1)瓦斯综合抽采巷合理切顶位置位于47.3 m高度的中细砂岩,为保证切顶效果,须设置49.9 m以保证将此岩层切落。确定了现场切顶卸压关键参数并进行工业性试验,采用了切顶爆破后,巷道最大高度由初始3.5 m降至3.24 m,断面收缩率为7.4%,有效控制了瓦斯抽采巷围岩稳定,巷道断面满足巷道正常抽采要求,保证了工作面安全稳定生产。

蛇形切割工艺在煤巷快速掘进中的应用分析

文章通过分析某煤矿综采工作面的工程概况,确定了顶板安全跨度和巷道受力情况。采用Midas GTS NX有限元软件模拟不同切割工艺路径下的巷道应力和变形情况。结果表明,自下而上的蛇形切割工艺能有效减小巷道变形量和应力集中,增强巷道的稳定性。在实际应用中,引入蛇形切割工艺和机载临时支护方案后,掘进进度从71 m/月提升至89 m/月,巷道稳定系数从1.5增加至1.9,显著提升了掘进效率和安全性。

采煤工作面切顶卸压留巷技术研究

文章以3302回风巷留巷为工程背景,对切顶卸压留巷技术方案及应用效果进行分析。在3302回风巷留巷中,通过高强锚索进行超前支护,为后续留巷创造良好条件;通过定向预裂爆破切顶使得留巷段顶板与采空区顶板形成切顶线,达到采空区顶板沿切顶线垮落;通过顶板临时支护及挡矸支护,确保采空区垮落期间顶板稳定并避免采空区破碎矸石入侵留巷空间。工程应用后,3302回风巷留巷段顶板下沉量控制在251 mm以内,巷道断面可满足后续使用需要。

综采工作面无煤柱开采技术研究

针对亿欣煤业15号煤综采工作面采用传统采煤工艺留设煤柱造成资源浪费严重、煤炭回收率低、巷道掘进及返修工程量大等问题,以15号煤XV1213巷道为背景开展无煤柱开采技术研究,通过数值模拟分析了巷道顶板无切缝和有切缝模型的应力和位移情况,验证了顶板切缝对巷道围岩应力和变形的改善作用,并根据工作面现场条件设计了巷恒阻大变形锚索关键参数、顶板定向预裂切缝关键参数和无煤柱自成巷支护方案。现场应用表明,无煤柱成巷区巷道顶板整体下沉量较小,碎石巷帮无明显侧鼓现象,实体煤帮无明显片帮现象,满足留巷安全使用要求。经计算,切顶卸压无煤柱开采每米可创造经济效益8763.28元,经济效益显著。

动压巷道围岩变形机理及其控制技术研究

针对寺河煤矿二号井动压巷道在工作面回采过程中存在的围岩变形严重及工作面支架阻力过大等问题,采用现场监测与数值模拟相结合的手段,对动压巷道围岩变形机理及其控制技术进行了系统研究。结果表明,巷道在经受掘进支护及工作面的开采动压影响后,围岩应力水平升高,且两侧应力不平衡,帮部不对称变形严重,巷道围岩变形主要分为单侧采用影响与两侧采动影响2个阶段,巷道变形主要是因为采区大巷两侧工作面采动产生的应力扰动作用,导致巷道承载性能持续恶化,围岩发生反复变形破坏。据此,研究提出采用预裂切顶卸压技术对动压巷道变形实施有效控制,确定合理的切顶卸压高度与角度分别为16.5 m与60°。通过现场实践,对动压巷道实施切顶卸压后,围岩顶底板及两帮移近量较卸压前得到了有效控制,工作面支架阻力显著降低,保证了工作面动压巷道围岩的稳定。

干河煤矿D工作面水力压裂切顶技术应用

干河煤矿结合工程实践,采用水力压裂切顶卸压+邻巷高预应力锚索补强+小煤柱护水平大巷+分区分段监测技术等综合手段,减弱回采超前及邻巷煤柱支承压力影响,并提前在邻巷施工高预应力锚索补强控制巷道围岩,帮缩底鼓量、帮缩底鼓范围大幅降低,为工作面快捷高效安全生产创造条件。

Comparative study of model tests on automatically formed roadway and gob-side entry driving in deep coal mines

Automatically formed roadway(AFR)by roof cutting with bolt grouting(RCBG)is a new deep coal mining technology.By using this technology,the broken roadway roof is strengthened,and roof cutting is applied to cut off stress transfer between the roadway and gob to ensure the collapse of the overlying strata.The roadway is automatically formed owing to the broken expansion characteristics of the collapsed strata and mining pressure.Taking the Suncun Coal Mine as the engineering background,the control effect of this new technology on roadways was studied.To compare the law of stress evolution and the surrounding rock control mechanisms between AFR and traditional gob-side entry driving,a comparative study of geomechanical model tests on the above methods was carried out.The results showed that the new technology of AFR by RCBG effectively reduced the stress concentration of the roadway compared with gob-side entry driving.The side abutment pressure peak of the solid coal side was reduced by 24.3%,which showed an obvious pressure-releasing effect.Moreover,the position of the side abutment pressure peak was far from the solid coal side,making it more beneficial for roadway stability.The deformation of AFR surrounding rock was also smaller than the deformation of the gob-side entry driving by the overload test.The former was more beneficial for roadway stability than the latter under higher stress conditions.Field application tests showed that the new technology can effectively control roadway deformation.Moreover,the technology reduced roadway excavation and avoided resource waste caused by reserved coal pillars.

Fixed-length roof cutting with vertical hydraulic fracture based on the stress shadow effect:A case study

Pre-driven longwall retracement roadway(PLRR)is commonly used in large mine shaft.The support crushing disasters occur frequently during the retracement,and roof management is necessary.Taking the 31107 panel as research background,the roof breaking structure of PLRR is analyzed.It is concluded that the roof cutting with vertical hydraulic fracture(HF)at a specified position,that is,fixed-length roof cutting,can reduce support load and keep immediate roof intact.The extended finite element method(XFEM)is applied to simulate hydraulic fracturing.The results show that both the axial and transverse hydraulic fracturing cannot effectively create vertical HFs.Therefore,a novel construction method of vertical HF based on the stress shadow effect(SSE)is proposed.The stress reversal region and HF orientation caused by the prefabricated hydraulic fracture(PF)are verified in simulation.The sub-vertical HFs are obtained between two PFs,the vertical extension range of which is much larger than that of directional hydraulic fracturing.The new construction method was used to determine the field plan for fixed-length roof cutting.The roof formed a stable suspended structure and deformation of the main PLRR was improved after hydraulic fracturing.

Mechanism and practice of rock control in deep large span cut holes

Deep large span cut holes are difficult to stabilize. The 7801 cut hole in the Lu'an Wuyang Mine was used as this project's background. The main factors affecting large span cut hole stability are analyzed. Pre- stressed bolting theory was used to design a roof control method for a large span roadway. By reducing the span and applying equal strength coordinated supports the rock could be stabilized. The control prin- ciples and methods are given herein along with the analysis. A double micro arch cross section roadway is defined and its use in solving the current problem is described. Beam arch theory was used to build a model of the double micro arch cross section roadway. A support reverse force model for the arch foot intersection was also derived. A support method based upon reducing the width of the large span in the cut hole is presented. These results show that the reduced span of the roadway roof plus the use of cable anchors and single supports gives an effective way to control the large span cut hole. On site monitoring showed that the reduced span support from the double micro arch cross section roadway design had a significant effect. The roadway surface displacement was small and harmful deformation of the cut hole was effectively controlled. This will ensure its long term stability.

数字孪生驱动的巷道自动成形截割虚拟调试方法研究

针对目前巷道自动成形截割控制调试周期长、调试成本大、安全风险大、成形质量难以评价等问题,提出了一种数字孪生驱动的巷道自动成形截割虚拟调试方法。采用基于即时外观建图(RTAP−MAP)技术重建巷道三维环境,构建掘进机控制系统模型,形成虚拟调试环境,并利用虚拟传感器技术实现物理空间到虚拟环境状态的精准映射。针对难以量化评估断面成形质量的问题,确立了巷道自动成形截割性能评价方法,以断面成形截割控制过程在数据传输中心的记录为基础,主要对断面成形精度、截割效率与油缸开关次数、硬岩切割调整、超挖欠挖4个评价指标进行计算,从而为深度学习算法的迭代优化提供精准反馈信号,并提出了一种融合强化学习的自动截割控制策略,以提高自动化作业的适应性和精确度。为验证该虚拟调试方法的有效性和准确性,搭建了掘进机自动控制实验平台,并将虚拟调试系统应用于掘进巷道成形截割自动控制程序中。虚拟仿真结果表明:①被调试软件在控制关键点位处的X,Y,Z轴定位误差的最大值分别为74.8,72.93,123.67 mm,说明虚拟调试方法的定位精度达到性能要求。②虚拟样机与物理样机轨迹基本一致,说明该调试方法实现了对物理空间的映射。应用结果表明:①强化学习控制器在虚拟掘进测试中适应了复杂环境,将虚拟传感器输入有效转换为精准控制指令,验证了模拟−现实迁移训练的可行性。通过处理掘进精度和避免超欠挖的实时反馈,控制器学习并优化了策略。②优化后的断面成形截割控制性能得到了提升,根据数据库中控制量时间戳的记录,用时126 s,较优化前耗时减少了8 s。③优化后截割部末端轨迹跟踪最大误差为6.0 mm,较优化前降低了0.3 mm,避免了截割轨迹抖动导致的欠挖,同时使得轨迹和断面更加平滑。

短横轴截割机器人直墙拱形巷道自动成形控制方法

针对掘进机在直墙拱形巷道掘进过程中存在定位难、截割效率低、成形质量差等问题,提出一种短横轴截割机器人及其自动成形控制方法。首先设计了串联式短横轴截割机器人结构,构建了短横轴截割机器人运动学模型,建立了截割臂升降油缸、滑移油缸及回转油缸伸缩量与截割头末端位姿的数学关系,提出了短横轴截割机器人直墙拱形巷道自动成形控制方法;其次研究分析了短横轴截割机器人截割头包络空间与直墙半圆拱形巷道空间耦合关系,确定了截割过程中截割轨迹关键点位置,提出了基于截割轨迹关键点的“弓”型截割轨迹规划方法;然后根据建立的短横轴截割机器人运动学模型,求解截割头在跟踪截割轨迹的过程中运动控制量和截割、修帮、扫底3个任务各个关节控制时序;最后以模糊PID为例,建立了短横轴截割机器人自动成形控制方法,利用Adams软件对短横轴截割机器人进行截割运动仿真试验。结果表明:利用“弓”型截割轨迹规划方法能够完成直墙拱形巷道的截割轨迹规划,控制截割头对截割轨道进行跟踪控制,实现了直墙拱形巷道断面的自动成形截割,截割成形的巷道最大欠挖量为48 mm,最大超挖量为21 mm,满足煤矿巷道成形质量要求。研究得出短横轴截割机器人可在沿巷道中线不左右移机的情况下,高效率、高质量地完成直墙拱形巷道断面自动成形截割任务。

双悬臂截割机器人相对动力学建模与力位混合控制研究

双悬臂截割机器人可解决传统单臂掘进机在截割大尺寸断面时效率低下的难题,但其与煤岩的动态交互影响控制性能。现有研究以双臂接触同一对象形成运动闭链为前提,无法满足双悬臂截割机器人双臂运动及末端截割头输出力的控制要求。针对该问题,设计了一种基于机器人相对动力学模型的力位混合控制系统。建立双悬臂截割机器人运动学和动力学模型,基于机器人的相对雅可比矩阵及虚位移与虚功原理推导出机器人的相对动力学模型,通过单一变量同时描述机器人双臂的运动状态,将机器人双臂独立的动力学模型整合为一个整体。基于机器人的相对动力学模型,设计了机器人双臂力位混合控制系统,通过李雅普诺夫函数验证了系统的稳定性和可行性。仿真结果表明:双悬臂截割工艺较单悬臂截割拥有更大的工作空间,具有一次性实现大断面截割的能力;双悬臂截割机器人力位混合控制系统能够完成对期望相对位置和期望相对力的同步跟踪,对截割头期望位置跟踪的绝对误差在0.3132 m以内,均方根误差为0.1447 m。

深部高瓦斯强动压巷道切顶卸压机制及技术研究

深部邻空巷道面临强动压、高瓦斯的双重困扰。为解决深部邻空巷道严重变形问题,以13131巷为工程背景,采用理论分析、数值模拟、现场试验等方法,研究了采空区侧向上覆岩层运动特征、邻空巷道围岩变形机制以及邻空巷道切顶卸压技术参数。结果表明:6.0m粉砂岩是上覆岩层亚关键层,弧形三角块破断导致厚硬岩层共同运动,致使侧向支承压力及其影响范围增大,造成邻空巷道严重变形;切顶卸压效果与切顶高度、切顶角度密切相关,只有当切顶高度达到关键层顶部时,才能有效降低邻空巷道变形量,超过关键层高度后,效果提升不再明显;当切顶角度为0°时,岩块传递的侧向支承压力最小,切顶角度由0°增加至10°时,邻空巷道变形量呈轻微上升趋势,由10°增加至20°时,邻空巷道变形量大幅增大。基于切顶关键技术参数及顶板瓦斯抽放钻孔空间分布特征,提出了“预留超前安全距离+留设抽放钻孔保护距离+封孔长度差异化+瓦斯监测与安全保障”爆破切顶技术方案,并开展了现场试验,有效控制了邻空巷道变形量,保证了顶板钻孔瓦斯抽采效果。