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.

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.

动压影响孤岛工作面巷道围岩“卸-支平衡”协同控制技术

煤矿深部工作面回采过程中,经常受到强开采动压作用影响,矿压显现强烈,巷道围岩变形破坏程度大,尤其对于孤岛工作面,动压影响更加显著,围岩控制难度成倍增加。为了解决深部孤岛工作面强动压影响回采巷道围岩控制问题,以2308工作面为研究背景,采用理论分析、数值模拟、现场验证等方法,首先对巷道围岩结构模型进行分析,确定影响工作面围岩稳定的主要因素;进一步对煤柱宽度和钻孔卸压2种方案进行研究,并根据巷道围岩的实际变形情况,确定巷道围岩的非对称支护参数,实现受强动压影响回采巷道的“卸-支平衡”协同控制方案。经过现场实践验证,2308工作面巷道顶底板移近量为260 mm,两帮移近量为471 mm,巷道围岩的整体性得到增强,变形得到有效控制;采用“卸-支平衡”方案对受动压影响巷道围岩的控制效果显著。

深部沿空巷道围岩主应力差演化规律与控制

针对千米深井沿空巷道围岩控制难题,以邢东矿2122运输巷为研究对象,采用FLAC3D模拟埋深550~1 250 m时巷道围岩主应力差与塑性区响应特征以及两帮主应力差演化规律。结果表明:1沿空巷道顶板与实体煤帮主应力差由浅到深均呈先增高后降低至趋稳的趋势,煤柱帮主应力差呈山峰型对称分布;2在埋深增加过程中,沿空巷道顶板和实体煤帮浅部主应力差敏感性度较小,进入中深部后变化较大;3随着埋深增加,两帮剪切、拉伸破坏区逐渐呈扇形分布并向深部扩展,且采空侧范围略大于巷道侧;4深部高应力和煤柱帮被主应力差长时间破坏使得实体煤帮主应力差峰值明显高于煤柱帮。基于此提出采用高预应力、强力支护系统进行深部沿空巷道围岩控制,并结合数值模拟研究结果确定了关键参数,现场实践表明,支护效果良好,实现了深部5 m宽煤柱沿空巷道围岩的有效控制。

大采深切顶卸压沿空掘巷技术

针对传统的沿空掘巷法下一区段巷道掘进时会出现的巷道大变形、冲击地压、瓦斯突出等现象,张双楼煤矿开展了大采深切顶卸压掘巷技术应用研究。通过对大采深回采工作面上一区段回采巷道切顶研究,得出了适合该矿的切顶深度、钻孔间距、装药量等参数。通过切顶卸压,加大岩石碎胀提高支撑上覆岩层的能力,减少顶板悬臂梁长度避免出现应力三角区,解决了下一区段巷道掘进应力集中的问题。

高强高预紧力锚网支护技术在深部矿井沿空掘巷中的应用

针对王楼煤矿深部采区回采巷道压力大、巷道变形严重,支护困难的问题,通过对七采区27304工作面的顶底板及煤层的岩性特征和煤巷的应力环境特点的分析,结合该矿的支护现状,并结合理论分析和数值模拟等手段,提出了高强高预紧力锚网索支护设计思路,并在27304工作面下煤巷进行应用,通过现场试验结果表明,采用该种方案实现了深部矿井沿空掘巷巷道支护的长期稳定。

深部沿空掘巷主应力差分布规律及煤柱宽度优化

以与围岩剪切破坏密切相关的主应力差为研究切入点,利用理论计算及数值模拟等研究方法,以赵固二矿11030运输巷沿空掘巷为工程背景,研究了深部回采工作面侧向采动应力场主应力差分布特征和不同煤柱宽度下沿空掘巷围岩主应力差分布规律,并提出了以主应力差分布规律为依据的深部沿空掘巷煤柱设计思路。研究结果发现:11030运输巷沿空掘巷前围岩可以分为主应力差降低区、主应力差升高区和主应力差稳定区;不同煤柱宽度下,深部沿空掘巷顶板、底板和煤壁帮围岩的主应力差呈单峰值曲线分布;而煤柱帮围岩主应力差,在煤柱宽度≤8 m时,主应力差呈单峰值曲线分布;而当煤柱宽度>8 m时,主应力差呈双峰值曲线分布,且位于浅部围岩的峰值点大小明显小于位于围岩深部围岩的峰值点大小。在此基础之上,结合理论计算确定了11030运输巷沿空掘巷合理煤柱宽度应为8 m,并进行了现场工业性试验。

深部煤层沿空掘巷围岩稳定性控制技术研究与应用

本文研究了深部煤层开采沿空掘巷支护技术方案,通过关键层理论对上覆岩层破断后形成的梁结构进行分析,运用薄板理论对关键层进行分析,根据极限平衡区宽度确定沿空掘巷的小煤柱留设宽度,最终利用高强预应力锚杆进行巷道支护。通过观测王楼煤矿七采区深部煤层沿空巷道的支护效果,发现巷道围岩稳定性保持良好。

深部倾斜煤层沿空掘巷围岩变形特征与控制技术研究

通过对深部倾斜煤层沿空掘巷掘、采两阶段围岩应力场与位移场的分析,揭示了该类巷道围岩非对称大变形特征:窄煤柱帮与底板变形量远大于实煤体帮及顶板,巷道整体断面收敛率大。产生该变形破坏特征的原因:1)巷道埋深大,围岩处于较高的应力环境中;2)护巷煤柱宽度及支护阻力过小,使其过早进入残余承载阶段;3)无支护底板作为变形破坏能量主要释放通道,加剧了巷道顶帮围岩整体下沉。通过对不同宽度护巷煤柱方案的数值模拟,合理确定了试验巷道护巷煤柱宽度及试验巷道支护技术与参数。工程实践表明,采用新支护技术后,巷道窄煤柱与底板非对称变形大变形得到了有效控制,保持了巷道长期稳定。

深井沿空掘巷围岩变形破坏特征及控制技术研究

针对深井高应力软岩巷道变形量大、变形持续时间长、巷道难支护等问题,以口孜东矿沿空巷道为工程背景,通过现场调研、地应力测试、矿物成分分析及巷道围岩力学性能测试等手段,揭示高地压、强扰动是巷道产生大变形破坏的主要动力源,低抗载性围岩破裂加剧了巷道围岩的结构风化和强度劣化,加剧了巷道扩容变形,构成巷道产生大变形的主要内因;巷道断面不合理,支护强度低,加剧了巷道围岩扩容变形,构成巷道大变形的主要外因。从巷道破坏模式方面分析巷道5种典型变形破坏特征及发生机制;通过现场观测,揭示巷道表面变形的空间非对称性、不同深度围岩变形的跳跃性,以及巷道围岩内部结构劣化的非均匀性和跳跃性;总结了巷道大变形机理是高应力驱动下塑性区劣化后的围岩产生显著的流变与强烈的扩容变形,加速了巷道的变形失稳。提出口孜东矿沿空掘巷以“高预应力主动支护、注浆改性加固、强帮护顶”为核心的沿空掘巷支护技术,现场监测表明,该支护方案可有效控制深部高应力软岩巷道变形。

深部高应力沿空掘巷非对称支护技术

为了解决深部高应力影响区沿空掘巷支护难题,以郭屯煤矿-808 m四采区辅助轨道巷为例,分析了巷道变形破坏特征及其影响因素,提出采用"高强高预应力让压锚杆+锚索+金属网+带梯"的非对称锚网索支护方案,并对支护方式和支护参数进行优化。采用有限差分软件FLAC3D,对深部高应力扰动围岩沿空掘巷所采用的非对称支护方案进行了数值模拟,与原方案相比,巷道围岩应力显著降低,顶底板和两帮收敛变形得到有效控制。现场应用及观测结果表明,在深部高应力影响区沿空掘巷采用非对称锚网索支护技术,对围岩应力重新分布起到了较好的作用,达到了理想的巷道围岩控制效果。