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.

千米深井动压巷道变形破坏主控因素及切顶护巷技术研究

为解决红阳三矿703工作面深部动压巷道支护困难问题,基于现场地质条件和动压巷道变形数据,分析了动压巷道变形破坏特征,确定了巷道变形破坏主要影响因素为巷道围岩强度低、高地应力、强开采动压,提出了切顶卸压+NPR恒阻大变形锚索支护控制技术并进行现场应用,有效控制了动压巷道的变形。现场实践表明,成巷区巷道顶板整体下沉量较小,实施切顶卸压后的巷道变形量与原支护相比,底鼓量平均减小30%,顶板下沉量平均减小33%,两帮移近量平均减小41%。

深部切顶沿空成巷关键参数研究及工程应用

传统充填沿空留巷工艺繁琐﹑留巷速度慢,与现代化高强度开采要求不相适应,由此提出了切顶沿空成巷无煤柱开采新技术,其中关键参数设计是该技术的核心问题之一,对留巷的稳定性具有较大影响。以城郊煤矿21304工作面为研究背景,采用理论分析、数值模拟和现场试验等方法,对切顶沿空成巷关键参数进行了系统研究。基于岩石碎胀自承特性和围岩结构"S-R"稳定原理,推导出切顶高度﹑切顶角度的理论计算公式;建立了聚能爆破力学模型,并结合数值模拟和现场试验,确定了聚能爆破装药量及钻孔间距。研究结果表明:合理的切顶参数能够切断巷道顶板与采空区岩层间的力学关系,使采空区顶板沿切缝顺利垮落,碎胀的矸石可有效支撑上覆顶板,限制其回转下沉,减弱覆岩运动对留巷的扰动作用,沿空巷道围岩变形量明显减小。根据理论计算﹑数值分析和现场试验研究成果,确定了城郊煤矿21304工作面切顶沿空成巷关键参数,并在现场进行了应用,回采后沿空巷道侧向顶板能够迅速切落形成巷帮,留巷稳定后各项指标均能满足现场使用要求。

Stability control of gate groups in deep wells

In order to study stability control methods for a deep gate group under complex stresses,we conducted field investigations and analyses of reasons for damage in the Xuzhou mining district.Three reasons are proposed:deep high stress,improper roadway layout and support technology.The stability control countermeasures of the gate group consist of an intensive design technology and responding bolt-mesh-anchor truss support technology.Our research method has been applied at the -1000 m level gate group in Qishan Coal Mine.Suitable countermeasures have been tested by field monitoring.

超长孤岛工作面沿空掘巷矿压显现规律及原因分析

为研究孤岛工作面条件下矿压显现规律及巷道支护,以两淮矿区刘庄矿120502超长孤岛工作面机巷为工程背景,通过现场实测以及FLAC^(3D)数值模拟软件对该孤岛工作面沿空掘巷矿压显现规律进行研究。结果表明:巷道顶板离层量较大,离层量最大达到117mm,且以浅部离层为主;在巷道掘进前期巷道围岩变形较小,随后巷道围岩变形随距巷道起点距离增加而增大,在距巷道起点600～800m之间变形更为剧烈,120503工作面采空区侧变形最大,平均值为180. 41mm,最大值为780mm,依次为煤体实侧(平均值为138. 23mm,最大值为445mm)、底鼓(平均值为124. 29mm,最大值为545mm)、顶板下沉(平均值为64. 03mm,最大值为430mm);由于垂直应力在煤柱内形成弹性核,使垂直应力达到32. 5MPa,工作面侧垂直应力达到26. 3MPa,相比增加了6. 2MPa,机巷邻近采空区侧受120502工作面开采影响大,使采空区变形增大;由于巷道采用直墙三心拱断面,顶部拱结构将垂直应力转换为切向应力,塑性区显示顶板受压底板受拉,由于岩石具有抗压不抗拉特性,因此顶板下沉小于底鼓量,并针对性地提出了巷道加强支护技术。工程实践表明,在初始支护设计的基础上,通过锚网索与喷浆、注浆联合等加强支护手段可以有效地对巷道围岩变形进行控制。