Mechanisms of support failure and prevention measures under double-layer room mining gobs——A case study: Shigetai coal mine

In the practice of mining shallow buried ultra-close seams,support failure tends to occur during the process of longwall undermining beneath two layers of room mining goaf(TLRMG).In this paper,the factors causing support failure are summarized into geology and mining technology.Combining column lithology and composite beam theory,the key stratum of the rock strata is determined.A finite element numerical simulation is used to analyze the overlying load distribution rule of the main roof for different plane positions of the upper and lower room mining pillars.The tributary area theory(TAT)is adopted to analyze the vertical load distribution of each pillar,and dynamic models of coal pillar instability and main roof fracture are established.Through key block instability analysis,two critical moments are established,of which critical moment A has the greater dynamic load strength.Great economic losses and safety hazards are created by the dynamic load of the fracturing of the main roof.To reduce these negative effects,a method of pulling out supports is developed and two alternative measures for support failure prevention are proposed:reinforcing stope supports in conjunction with reducing mining height,or drilling ground holes to pre-split the main roof.Based on a comprehensive consideration of economic factors and the two categories of support failure causes,the method of reinforcing stope supports while reducing mining height was selected for use on the mining site.

Identifcation of large-scale goaf instability in underground mine using particle swarm optimization and support vector machine

An approach which combines particle swarm optimization and support vector machine(PSO–SVM)is proposed to forecast large-scale goaf instability(LSGI).Firstly,influencing factors of goaf safety are analyzed,and following parameters were selected as evaluation indexes in the LSGI:uniaxial compressive strength(UCS)of rock,elastic modulus(E)of rock,rock quality designation(RQD),area ration of pillar(Sp),the ratio of width to height of the pillar(w/h),depth of ore body(H),volume of goaf(V),dip of ore body(a)and area of goaf(Sg).Then LSGI forecasting model by PSO-SVM was established according to the influencing factors.The performance of hybrid model(PSO+SVM=PSO–SVM)has been compared with the grid search method of support vector machine(GSM–SVM)model.The actual data of 40 goafs are applied to research the forecasting ability of the proposed method,and two cases of underground mine are also validated by the proposed model.The results indicated that the heuristic algorithm of PSO can speed up the SVM parameter optimization search,and the predictive ability of the PSO–SVM model with the RBF kernel function is acceptable and robust,which might hold a high potential to become a useful tool in goaf risky prediction research.

Double-directional control bolt support technology and engineering application at large span Y-type intersections in deep coal mines

Under deep and complex geological conditions,severe deformation occurs at intersection points of Y-type roadways with large cross sections during engineering projects in coal mines,especially at junction arches.Based on in-situ investigations and theoretical studies,we have summarized typical forms of destruction and identified high stress and unrestricted support at both sides of junction arch as its main causes.In this study,we also presented double-directional control bolt support technology for a large Y-type span intersection,applied to deep intersection engineering in the Jiahe Coal Mine,which has proved effective.

Cable-truss supporting system for gob-side entry driving in deep mine and its application

In order to solve the large deformation controlling problem for surrounding rock of gob-side entry driving under common cable anchor support in deep mine, site survey, physical modeling experiment, numerical simulation and field measurement were synthetically used to analyze the deformation and failure characteristics of surrounding rock. Besides, applicability analysis, prestress field distribution characteristics of surrounding rock and the control effect on large deformation of surrounding rock were also further studied for the gob-side entry driving in deep mine using the cable-truss supporting system. The results show that, first, compared with no support and traditional bolt anchor support, roof cable-truss system can effectively restrain the initiation and propagation of tensile cracks in the roof surrounding rock and arc shear cracks in the two sides, moreover, the broken development of surrounding rock, roof separation and extrusion deformation between the two sides of the roadway are all controlled; second, a prestressed belt of trapezoidal shape is generated in the surrounding rock by the cable-truss supporting system, and the prestress field range is wide. Especially, the prestress concentration belt in the shallow surrounding rock can greatly improve the anchoring strength and deformation resisting capability of the rock stratum;third, an optimized support system of ‘‘roof and side anchor net beam, roof cable-truss supporting system and anchor cable of the narrow coal pillar" was put forward, and the support optimization design and field industrial test were conducted for the gob-side entry driving of the working face 5302 in Tangkou Mine, from which a good supporting effect was obtained.

Stability assessment of rock surrounding an I-beam supported retreating roadway

The installation of a back-wall guard-board is the key to successfully supporting underground retreating roadways in coal mines. Based on the coordinate support principle, and using an I-shaped steel support for the surrounding rock, a mechanical model was developed for the stability of the roadway support and surrounding rock. Analysis of the bearing capacity of the roof back-wall guard-board and modelling of the equations for the maximum deflection and the maximum compressive stress of the top and side beams of the I-shaped steel support were undertaken. Simultaneously, the model was used to calculate and analyse the stability of the top and side beams of the I-shaped steel support structure and analyse the criteria for their stability. The results provide a reliable theoretical basis for the judgment of the stability of the surrounding rock and support structure. The theoretical evaluation results are consistent with field data. Finally, the key support parameters of the top and side beams of the I-shaped steel support structure and the variation of the maximum deflection and the maximum compressive stress as affected by the influence of the guard-board length were investigated. It is concluded that, as the back-board length increases, the maximum compressive stress in the top beam of the I-shaped steel support increases while the compressive stress in the side beam decreases. The results show that the accuracy of judgment of the stability of a supported retreating roadway is improved, providing guidance for the design of such typical I-shaped steel support and back-board structures.

基于可编程逻辑控制器的煤矿综采组合开关结构设计

针对有效、统一控制煤矿综采工作面多种采煤设备为目的,设计基于可编程逻辑控制器的煤矿综采工作面配套组合开关结构。该开关结构分为主控制电路、次控制电路,两种电路均与液晶显示模块相连。通过液晶显示模块的界面将电路状态反馈给管理人员,两种控制电路主要通过可编程逻辑控制器和继电器、信号提醒、保护回路相连,分别完成电源供应、警报信息提醒、采煤设备连接状态管理。实验结果表明,在过载、漏电工况中可用电气互锁的方式保证采煤机状态不出现异常变化,完成异常采煤设备的统一管理,最高节能比例达到11.2%,最低节能比例也能达到7.8%,由此证明设计的方法具有一定研究价值。

王家岭矿18109工作面末采技术研究

为提高综放工作面末采效率及安全保障能力,以王家岭矿18109工作面为研究对象,结合现场条件及开采设备布置等给出末采技术方案及顶板管理措施。18109工作面在末采期间采用铺设柔性网、锚索(中空注浆锚索)等方式有效维护了末采期间顶板稳定;同时通过采煤机截割回撤通道方式避免了预掘回撤通道存在的支护难度大、围岩变形严重等问题。现场应用后,王家岭矿18109末采阶段顶板、煤壁及回撤通道等始终保持稳定,保持2.4 m/d的推进速度,为采面安全高效回采奠定了良好基础。

深部巷道支护方案数值模拟研究

为研究深部开采巷道支护方案,采用Phase 2D软件,建立素喷射砼支护、锚网支护和喷锚网联合支护3种数值模型,分析了在凝灰岩和铜硫矿两种围岩条件下巷道位移、应力和塑性区分布规律。发现巷道位移变形主要出现在拱肩和拱墙位置,3种支护方式均可以有效控制围岩变形,支护效果表现为50 mm素喷<锚网支护<喷锚网联合支护,建议矿山在凝灰岩条件下使用喷锚网联合支护。研究可为类似条件巷道的支护提供经验借鉴。

综放工作面液压支架快速回撤技术研究

以11203综放工作面液压支架回撤为工程背景,在分析采面地质、开采设备配备基础上,构建末采期间顶板控制及设备回撤方案并进行工程应用。在11203综放工作面回撤期间采用全断面掩护支架法可提高回撤通道顶板稳定性,同时使用架前撤架装置+铲板车+框式支架车协同方式提高液压支架回撤机械化程度、效率,实现液压支架回撤环节平行作业。现场应用后,11203综放工作面液压支架回撤效率得以明显提高,实现了快速回撤、减人增效的目标。

基于数值模拟的浅埋煤层综采工作面覆岩移动和矿压规律研究

为直观研究煤矿采场支架与围岩之间的作用关系,基于CDEM数值模拟软件,建立与“工作面推进-顶板岩层运动”实际物理过程相符的数值模型,实现采煤工作面液压支架与围岩耦合的二维动态数值模拟。以大湾煤矿12311综采工作面为工程背景,直观地研究浅埋煤层综采工作面覆岩结构运动和矿压规律。结果表明,工作面基本顶初次和周期来压期间,支架工作阻力相差不大;工作面超前压力影响区域为工作面前方采高大小的2.0~3.0倍范围内;工作面基本顶初次和周期来压时,支架平均工作阻力为9.0~11.0倍采高的岩层重量载荷。模拟结果与现场监测数据一致,为研究支架-围岩关系提供了新的方法。

复杂地质条件下的煤矿掘进支护技术探究

探究了复杂地质条件下的煤矿掘进支护技术,旨在为煤炭行业提供更有效的支护方法。首先,回顾了掘进支护的定义、目的和历史背景,为后续的技术改进提供了基础;然后,对复杂地质条件,如断层地质和软岩地质等进行了分析,探讨了这些地质条件对采矿掘进支护工作的直接和间接影响,以凸显其重要性;最后,介绍了在复杂地质条件下应用的煤矿掘进支护技术,包括锚杆支护、液压支架、钻孔爆破及其他创新支护技术,这些技术有望改善掘进支护的效率和安全性,帮助煤矿更好地应对复杂地质条件下的挑战,确保了矿山的安全性和生产效益。

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。

厚煤层综采工作面矿压规律及压架治理实践

针对榆树坡煤业5106工作面顶板压架问题,分析了压架原因,由于上覆巨型集中煤柱应力影响,并对相邻工作面的矿压规律进行了对比分析后,对本工作面的开采进行了危险程度分区,并采用对应控制措施,进行了井下试验,顶板事故得到了有效解决。

巷道液压支架立柱力学特性研究

文章针对巷道液压支架立柱性能问题,深入分析了液压支架的工作流程,构建了理论力学模型,并通过ABAQUS软件进行仿真实验,评估了立柱在不同伸出长度和偏载角度下的力学性能。研究发现,立柱的应力分布和变形情况受伸出长度和偏载角度的影响,从而为液压支架设计和优化提供了理论支撑和实践参考。

综放采面边角煤一次增架开采技术应用

为保证枣泉煤矿110201(Ⅲ)综放工作面边角煤安全回采,通过分析综放工作面矿压规律,针对该工作面条件提出了一次增架开采技术。厚煤层综放工作面边角煤一次增架开采技术是将所需增加支架提前安装于增架切眼,同时采用铺设阻燃聚酯纤维增强柔性网控制顶板。现场应用结果表明:工作面增加支架及溜槽共计46台,用时6天,其间无明显来压,风机两巷围岩控制效果良好,安全高效回收边角煤180.3万t,增加经济收入10 241.04万元,带来巨大的社会和经济效益,为综放工作面边角煤回采提供了一种快速安全高效的方法。

中文Web文本挖掘系统WebTextMiner开发

W eb文本挖掘系统的开发对W eb文本挖掘的研究有着很大的推进作用。因此在对基于SVM的中文网页分类器性能研究的基础上,根据研究和实用的需要,实现了一个性能较好的中文W eb文本挖掘系统。

快速掘进巷道支护及掘进工艺设计

巷道掘进不仅是煤矿开采的重要环节之一,也是安全回采的重要前提,对于煤矿效益具有显著影响。为了提高巷道的快速掘进效率及其安全性,文章以某煤矿的快速掘进巷道为例,分析影响快速掘进的三个因素;根据情况计算快速掘进巷道支护参数,设计支护方案,并采用FLAC 3D数值计算模拟,验证支护方案的可行性;结合快速掘进机组的整体特点,优化巷道快速掘进工艺,并调整锚杆、锚索安装情况与锚杆转载机滞后距离。通过验证可知,该设计提高了掘进速率,可为类似项目提供参考。

智能工作面中采煤机与液压支架的协同控制分析

在矿采机械化水平不断提高的背景下,基于自动化、数字化技术的应用,要做好智采工作面“三机”中液压支架和采煤机的协同控制。以一煤矿井下作业工况为例,参考支架控制与采煤机控制相互独立的特征并开展协同控制分析。在了解“三机”控制参数的匹配性后,讨论了采煤机和液压支架的协同控制原理,从硬件功能、软件流程、通信方案等方面补充优化了协同控制方案。最后,对协同控制方案进行实际验证,证明其具备监控功能和协调控制功能,且具有采煤效率和安全性等价值。

煤巷快速掘进支护工艺优化

旨在优化煤巷快速掘进支护工艺,以提高煤矿的掘进效率和安全性。研究涵盖了支护参数的确定、临时与永久支护方案的优化、作业及循环方式的改进以及围岩变形的实时监测。通过在东兴矿实施的案例研究,优化后的支护方案能显著控制围岩变形、地质风险,提升了掘进作业的安全与效率。该研究成果为煤矿快速掘进技术提供了施工经验,具有较好的应用前景和推广价值。

王坪矿8306工作面过岩墙顶板管理技术探讨

针对王坪矿303盘区8306巷掘进中遇到的辉绿岩墙,制定了工作面上、下顺槽顶板采用锚杆+锚索+钢带+金属网+锚固剂+喷浆联合支护方案,并提出了工作面顶板管理措施,有效控制了巷道围岩变形,工作面安全顺利通过岩墙,实现了安全连续开采。