我国煤炭深部开采冲击地压特征、类型及分源防控技术

Characteristics,types and prevention and control technology of rock burst in deep coal mining in China

我国煤炭资源大规模步入深部开采,深部开采冲击地压事故频繁发生,为了厘清深部开采冲击地压特点、启动类型以及防治与浅部开采的区别,为深部开采防治冲击地压提供理论与技术指导,以我国煤炭资源深部开采冲击地压特征研究为切入点,从诱发冲击地压的载荷源角度,结合工程实例,建立力学模型,研究提出了我国深部开采冲击地压的3种类型,最后提出了深部开采巷道冲击地压动静载荷分源防控方法。结果表明,我国煤炭深部开采冲击地压特征总体表现为因基础静载荷充足,发生门槛降低,冲击显现位置点多面广,发生原理隐蔽性、自发性、时滞性占比大,防治范围扩大,应力恢复快,高强度、长时效卸压要求突出;将我国煤炭深部开采冲击地压划分为3种类型,即深部动静载叠加型、深部高静载加载型、深部高静载卸荷型。深部动静载叠加型,因深部煤炭资源高地压环境,与浅部相比,较高的基础静载荷获得微动载扰动、叠加可发生冲击地压。深部高静载加载型冲击地压,其静载荷缓慢对极限平衡区加载过程冲击是材料失稳,导致工程结构体结构动力失稳的结果,而深部高静载卸荷型冲击地压,其高静载荷最小阻抗带减小,静载荷卸荷过程是围岩结构稳定性遭到破坏,导致工程结构体材料动力失稳的结果,2者存在本质差别;深部冲击地压防控与常规浅埋冲击地压防控,差别在于基础静载荷充足,增量顶板等动载荷来源复杂,冲击危险区域基础静载荷获取增量静、动载荷门槛降低,因此必须高强度、长时效实现静、动载荷源分源防控,阻止诱发冲击地压的载荷条件形成;在动静载荷分源防控指导思想下,针对顶板动载荷源,开发了顶板“钻-切-压”一体化技术,深度弱化顶板,消除顶板动载源;针对巷道两帮垂直应力集中,开发了煤层一次成孔300 mm超大直径无人钻孔技术,高强度、长时效疏导煤体垂直应力;针对巷道底板高水平应力,开发了巷道底角联排桩基,高强度切断水平应力,阻止底板冲击滑移等技术,现场应用效果良好。

In view of the large-scale deep mining of coal resources and the frequent occurrence of deep mining rock burst accidents in China,in order to clarify the characteristics of rock burst and its initiation types in deep mining and the difference of rock burst prevention measures between deep mining and shallow mining,and provide a theoretical and technical guidance for deep mining rock burst prevention and control,based on the research on the characteristics of deep mining rock burst in China,from the perspective of the load source of induced rock burst,and combining with the engineering examples,a mechanical model of rock burst in deep mining has been established,and three types of rock burst in deep mining in China have been put forward.Also,the dynamic and static load source control method of rock burst in deep mining roadway has been developed.The results show that the characteristics of rock burst in deep coal mining in China are as follows:due to the foundation static load is sufficient,the threshold of rock burst becomes lower,and the location of rock burst becomes widespread.Also,the occurrence percentages of rock burst with hidden principle,spontaneous and time-delay becomes high,the scope of prevention and control becomes expanded,the stress recovery becomes fast,and the requirements of high strength and long-term pressure relief becomes outstanding.The rock burst in deep coal mining in China is divided into three types,that is,deep dynamic static load superposition type,deep high static load loading type,and deep high static load unloading type.Because of the high pressure environment of deep coal resources,compared with the shallow part,the higher foundation static load can obtain the fretting load disturbance and their superimposition can produce a rock burst.The deep high static load loading can impact the ground pressure during the loading process at the limit equilibrium area and result in material instability,which leads to the dynamic instability of the engineering structure.While the deep high static load unloading can impact the ground pressure and reduce the minimum impedance band of high static load,and the static load unloading process is the result of the destruction of the stability of surrounding rock structure,which leads to the dynamic instability of the engineering structure material.Therefore,there are essential differences between the two.Comparing with the prevention and control of conventional shallow buried impact ground pressure,the prevention and control of deep impact ground pressure shows that the foundation static load is sufficient,the dynamic load sources such as incremental roof are complex,and the threshold of acquiring incremental static load and dynamic load in the impact dangerous area is reduced.Therefore,the prevention and control of static and dynamic load sources must be realized with high intensity and long time,so as to prevent the formation of load inducing impact ground pressure conditions.Under the guidance of dynamic and static load separate source control concept,the roof“drill-cut-pressure”integration technology has been developed for roof dynamic load source to weaken the roof in depth and eliminate the roof dynamic load source.For the vertical stress concentration at the two sides of the roadway,the technology of 300 mm large diameter single hole drilling has been developed for the coal seam to mitigate the vertical stress of the coal body with high intensity and long time process.For the high horizontal stress at the bottom of roadway,the technology of installing pile foundation at the bottom corner of roadway has been developed,strongly cutting the horizontal stress and preventing the floor from impact and sliding.The mine applications of the technologies developed show an excellent effect.