Rockburst mechanism research and its control

A new rockburst classification, innovative works in developing a ‘‘strainburst test machine" and an‘‘impact-induced rockburst test machine" that can reproduce rockbursts in laboratory were researched.New concepts were proposed regarding the stress paths that take into account both the static and dynamic stresses analogous to that at excavation boundaries for generating artificially-induced strainburst and impact-induced rockburst. As an important method for rockburst control, a novel energyabsorbing bolt was developed, which has a constant-resistance under both static and impact loadings and a large-elongation capacity for containing large deformations of rock masses under burst-prone conditions.

Practices on rockburst prevention and control in headrace tunnels of Jinping II hydropower station

Rockburst problems induced by high in-situ stresses were prominent during construction of the headrace tunnels of Jinping II hydropower station. The rockbursts occurred in various forms, and it is necessary to take pertinent measures for integrated prevention and control of rockbursts. In view of the rockburst characteristics during tunnel construction of Jinping II hydropower station, the engineering geological conditions were presented, and the features, mechanisms and forms of rockbursts observed during construction were analyzed in detail. A large number of scientific researches, experiments and applications were conducted. Multiple measures were adopted to prevent and control rockbursts, including the prediction and early warning measures, stress relief by blasting in advance, optimized blasting design and optimized tunnel support in the tunnel sections prone to strong rockbursts. The effectiveness of these prevention and control measures was evaluated. Experiences have been accumulated through a great number of helpful explorations and practices for rockburst prevention and control. A comprehensive rockburst prevention and control system has been gradually established.

PREDICTION AND CONTROL OF ROCKBURST DURING DEEP EXCAVATION OF A GOLD MINE IN CHINA

The studies of prediction and control of rockburst are presented during deep excavation in a gold mine in China. Firstly,the stress-relief method is used to obtain a vast amount of data about initial geostress. Secondly,3D FEM analyses of large scale are performed to find out the law of geostress distribution at various excavation levels of the mining area. At the same time,as an equally important measure,six typical kinds of rock blocks are sampled for the experimental study of rockburst tendency. According to the synthesized results of the theoretical and testing results,the methods of brittleness coefficient,brittle index and stress,and so on,are adopted. Finally,the evaluation on the possibility of rockbursts is given that may take place at the deep mining area and some effective measures are put forward to prevent and control the rockburst.

Research on the mechanism of rockburst induced by mined coal-rock linkage of sharply inclined coal seams

In recent years,the mining depth of steeply inclined coal seams in the Urumqi mining area has gradually increased.Local deformation of mining coal-rock results in frequent rockbursts.This has become a critical issue that affects the safe mining of deep,steeply inclined coal seams.In this work,we adopt a perspective centered on localized deformation in coal-rock mining and systematically combine theoretical analyses and extensive data mining of voluminous microseismic data.We describe a mechanical model for the urgently inclined mining of both the sandwiched rock pillar and the roof,explaining the mechanical response behavior of key disaster-prone zones within the deep working face,affected by the dynamics of deep mining.By exploring the spatial correlation inherent in extensive microseismic data,we delineate the“time-space”response relationship that governs the dynamic failure of coal-rock during the progression of the sharply inclined working face.The results disclose that(1)the distinctive coal-rock occurrence structure characterized by a“sandwiched rock pillar-B6 roof”constitutes the origin of rockburst in the southern mining area of the Wudong Coal Mine,with both elements presenting different degrees of deformation localization with increasing mining depth.(2)As mining depth increases,the bending deformation and energy accumulation within the rock pillar and roof show nonlinear acceleration.The localized deformation of deep,steeply inclined coal-rock engenders the spatial superposition of squeezing and prying effects in both the strike and dip directions,increasing the energy distribution disparity and stress asymmetry of the“sandwiched rock pillar-B3+6 coal seam-B6 roof”configuration.This makes worse the propensity for frequent dynamic disasters in the working face.(3)The developed high-energy distortion zone“inner-outer”control technology effectively reduces high stress concentration and energy distortion in the surrounding rock.After implementation,the average apparent resistivity in the rock pillar and B6 roof substantially increased by 430%and 300%,respectively,thus guaranteeing the safe and efficient development of steeply inclined coal seams.

Characteristics of rockburst and its mining technology in mines

In order to resolve how to mine under the condition of high stress with rockburst, this paper analyzes the law of rockburst, and considers that most of the rockbursts occur in the high stress area of stope. A method of rockburst forecast and its steps are given, and three different stages of rockburst are identified. Furthermore, this paper considers that blasting energy can effectively control rockburst by changing the characteristics of rock mass, which decreases the probability of rockburst happening. According to characteristics of rockburst, two feasible mining techniques under rockburst conditions are put forward, that is stoping and filling method, and sublevel caving method of mining without any sills in hanging wall.

岩爆机制及其控制

随着岩体工程向深部发展,开挖引发的围岩大变形和强冲击诱发的动力破坏日益严峻。岩爆作为深部地下工程中常见的一种强动力灾害,被称为岩土工程界的“癌症”,其具有突发性特点,难以有效预报及防治,严重地威胁着施工人员的安全和设备的正常运行。通过对比岩石在真三轴卸荷和单轴压缩这2种应力路径下的储能差异,对岩爆多余能量机制进行探讨。首先,根据岩爆诱发机制的不同,将岩爆分为由应力集中导致的应变型岩爆和扰动诱发的冲击岩爆。然后,模拟开挖诱发的不同类型岩爆的应力路径进而在室内再现各种岩爆现象,并对其机制进行研究,自主研发3套真三轴岩爆模拟试验系统:第1代应变岩爆试验系统、第2代应变岩爆试验系统、冲击岩爆试验系统。同时,在实验室内成功模拟不同类型的岩爆:巷道应变岩爆、巷道交叉点应变岩爆、3个临空面矿柱应变岩爆、矿柱应变岩爆以及动荷载诱发的冲击岩爆。最后,为有效控制岩爆灾害,提出开挖补偿法,并研发具有负泊松比效应的宏观和微观NPR锚杆/索。工程实践证明,NPR锚杆/索能提供高预应力来补偿开挖造成的应力损失,同时具备良好的延展性和吸能效果,可为岩爆灾害的防治提供有效途径。

基于CiteSpace的国内冲击地压防治文献可视化知识图谱分析

为探究我国冲击地压防治领域的研究历程及进展,采用CiteSpace软件对1994—2023年间收录于CNKI数据库的2891篇该领域研究文献进行可视化知识图谱分析。首先探明文献在时间轴及发表期刊的分布情况,然后针对研究机构和研究人员进行共现分析,最后通过关键词的聚类、共现和突现分析,对国内冲击地压防治领域的研究文献进行分析总结。研究结果表明:我国冲击地压防治研究发展历程,可按时间划分为稳定发展期、爆发增长期和持续波动期;以《煤炭学报》《煤矿安全》《煤炭科学技术》《采矿与安全工程学报》等期刊为主要交流平台;主要研究力量包括窦林名、潘一山、姜福兴等核心作者团队及中国矿业大学、辽宁工程技术大学、煤炭科学研究总院有限公司等研究机构,且组织之间合作较频繁;“厚硬顶板、动静载、巨厚砾岩、能量耗散、围岩协同控制、水力压裂”等是研究领域的高频关键词;根据关键词突现,得到随时间变化的关键词演化图谱。研究结果以期为冲击地压防治领域的研究提供科学参考。

多源数据融合的深埋隧道岩爆预测方法

为提高隧道设计阶段未开挖区域的岩爆预测准确性,提出了一种多源数据融合的隧道岩爆预测方法.综合隧道勘察和施工阶段的不同地质信息,采用基于证据关联系数的加权融合技术,构建了隧道精细化三维动态地质模型.建立了基于强度理论的岩爆可能性判定方法和基于能量理论的岩爆烈度预测方法,通过Hoek-Brown强度准则判断围岩是否发生岩爆,利用储能极限阈值和能量释放指数划分岩爆烈度,并将其应用于四川某隧道工程中.结果表明,所提方法可以实现隧道掌子面前方30 m范围内的岩爆精准预测,预测结果与隧道开挖实际岩爆的吻合率为95.8%.因此,该预测方法能够在隧道施工前预判岩爆烈度,为隧道岩爆防治提供指导.

胡家河地面水平井压裂防治冲击地压管理实践

胡家河矿为解决回采工作面高位坚硬顶板难以及时垮落的问题,引进地面“L”型水平井分段压裂技术,采取井上和井下联合监测压裂施工的方法,对压裂效果进行分析。胡家河矿在施工开展期间为规范压裂技术实施、合理分配人员和及时解决现场问题,构建了以“地面水平井分段压裂”为中心,“五+”协作统筹推进工作,做到六项反馈与确认,七大环节优化,最终形成了“156677”地面水力压裂管理体系。为推动同类矿井冲击地压防治技术研究工作提供新思路。

金属矿深部开采岩爆灾害防控研究进展与工程实践

随着浅部金属矿产资源的日益枯竭,金属矿山深部开采势在必行。开采进入深部后,高应力等复杂地质环境使得岩爆等灾害问题凸显,成为制约金属矿深部开采的主要问题之一。尽管岩爆灾害问题由来已久,但受其发生机制和监测手段的限制,始终未能得到有效解决。首先,通过文献调研,对岩爆评价体系和岩爆防控技术进行了系统的总结与归纳。结果表明,当前所提出的岩爆评价体系较多,能够对岩爆灾害的等级和倾向性进行较好地评价与预测。在岩爆防控技术体系方面,按照灾害处置时机和防护机制,可分为被动式防控技术和主动式防控技术两类。其次,基于开采方案优化和应力环境再造思想发展起来的整体规划理念,为金属矿深部开采岩爆灾害防控提供了新思路与新方法。最后,以三山岛金矿深部开采为背景,验证了整体规划理念下卸荷采矿方案在岩爆灾害防控上的优势与效果,为未来金属矿山深部开采岩爆灾害的超前干预与主动防控提供了有效借鉴。

高地应力水平层状硬岩隧道岩爆分级与防控技术研究

本文依托乐汉高速大峡谷隧道,总结分析了高地应力水平层岩爆的特征并提出了岩爆分级标准。在岩爆分级的基础上,提出了针对不同岩爆等级的处置措施。现场实践结果表明,对于弱岩爆可以采用全断面法开挖,降低扰动次数。对于中~强岩爆段,宜采取短进尺分部开挖,降低爆破对围岩的一次性扰动,同时采取应力释放孔、应力解除爆破孔等辅助措施提前释放围岩应力。

冲击地压煤层智能开采关键技术研究与实践

如何实现深部冲击地压煤层智能安全高效开采是煤炭开采面临的一项重大工程技术难题。该问题的核心内涵在于冲击地压煤层开采的智能化、无人化和本质安全化,通过煤岩冲击风险的智能精准感知与预警,以及采掘工程的自适应与自优化,形成智能防冲控采技术,实现由工程致灾向工程防灾、工程减灾的根本转变。通过开采源头设计、顶板区域压裂、局部靶向治理、强化巷道支护等措施为冲击地压煤层安全高效开采创造低应力环境和巷道安全空间。在此基础上,开发融合静态地质、动态监测、工况环境、人员定位、生产组织、历史数据等信息的大数据分析软件平台,以及融合冲击地压决策信息的智能化开采控制系统,将防冲信息源转化为智能开采控制源,形成了“低压快推,中压慢采,高压停产”的柔性智能推采新模式。通过现场应用表明,在智能防冲控采区,工作面及巷道矿压显现程度更小,煤岩能量释放更稳定,有利于冲击产能的合理释放。

煤层防冲卸压钻孔动载响应规律及其极限性

冲击危险性巷道围岩遭受外界动载荷扰动,常导致冲击地压发生。为了探索煤层大直径预卸压钻孔在动载扰动条件下的防冲卸压作用,综合采用理论分析、实验室试验以及数值模拟等方法,开展煤层防冲卸压钻孔动载响应规律及其极限性研究。结果表明:大直径钻孔卸压区内的煤体形成弱结构,增大了衰减动载的能力,降低了冲击发生的可能性。低动载扰动下,孔洞裂隙扩展,声发射累计事件随着扰动周期增加呈上升趋势;较高动载扰动下,钻孔煤样损伤破裂程度加剧,声发射事件以高能量为主。随着动载能级和扰动周期增加,应力集中区、弹性高能区与钻孔之间的距离缩短,影响范围增大,围岩运动趋势增强,弹性能集聚程度增加;在低动载能级扰动下,钻孔发挥耗能卸压防冲的作用,能够维护围岩的稳定性,在高能级动载扰动驱动下,大直径钻孔防冲失效,钻孔孔壁易发生动力失稳破坏,造成围岩失稳。总体上大直径卸压钻孔存在弱化结构,能够耗能减冲,降低动载扰动程度,但在高能、高频动载扰动下,卸压钻孔围岩运动趋势增强,破裂响应程度剧烈,防冲效能存在极限性。

岩爆及其判据和防治

岩爆研究可以追溯到18世纪上半叶。迄今为止,虽然诸多科研成果已经问世,但岩爆仍然是一个世界性难题。作为一般性的论述,首先提供一些背景材料,涉及到国内外一些工程实例、研究方法等。然后,叙述国际范围内常用的一些岩爆判据和岩爆分级方法;论述岩爆的预测和预报;对岩爆防治,包括应力解除钻孔、注水湿化和锚固等方法进行综述。最后,对锦屏二级水电站辅助洞发生的岩爆实例进行重点介绍,并在综合已有资料的基础上对岩爆判据、分级及防治等提出意见和建议。

高地应力区大直径TBM掘进岩爆风险控制

锦屏二级水电站1#,3#引水隧洞采用TBM掘进,中部深埋洞段岩爆风险突出。为制定合理可行的掘进方案与岩爆防治措施,在前人研究基础上,结合工程实际情况,采用多种数值分析手段,评价不同形式导洞开掘,对降低岩爆风险的影响。3种导洞开挖方式均可以显著地降低TBM掘进的岩爆风险,选择何种形式的导洞主要从设备和经济效益角度进行决策。据此提出高地应力区大直径TBM掘进岩爆风险控制措施,施工中结合钻爆法导洞预处理、应力解除爆破并辅以及时、系统、高质量的支护,降低岩爆风险,确保施工及结构安全。

锦屏二级水电站引水隧洞工程强岩爆综合防治措施研究

锦屏二级引水隧洞工程一般埋深1500—2000m，最大埋深2525m，具备发生强至极强岩爆的条件，工程开工以来已发生多次强岩爆。为最大限度降低强岩爆对工程安全和进度的影响，结合辅助洞和排水洞的施工经验，锦屏二级引水隧洞工程采用了微震监测、应力爆破解除、中空预应力注浆锚杆、水涨式锚杆、纳米仿钢纤维混凝土等综合防治措施。这些措施的综合运用在水电和交通隧道工程领域尚属首次，并已取得一定成果。

岩爆研究现状综述

岩爆是一种世界性的地质灾害,极大地威胁着矿山施工人员和设备的安全。目前,国内外在岩爆方面做了大量的研究工作,但是,由于岩爆问题极为复杂,还没有成熟的理论和方法。针对岩爆定义、岩爆发生机理、岩爆预测预报、岩爆控制的研究现状,进行了归纳分析与评述,并在某些方面提出了新的见解。

有色金属深井采矿研究现状与科学前沿

介绍了国内外金属矿山深部开采技术与研究概况,提出了诱变深井高应力、高地温、高井深为有利因素,变革深井开采技术所应解决的关键科学问题。

岩爆孕育过程的动态调控

针对岩爆孕育过程的特征、规律和机制,提出"优化开挖方案减少应力和能量聚集→预释放和转移能量→设计合理的支护参数吸收能量"的岩爆"三步走"防控理论以及在此基础上基于开挖过程中微震信息时空演化的岩爆动态调控理论。在施工过程中,根据实测到的微震信息演化规律进行岩爆等级预警,据此进行反馈分析和动态调控,运用"三步走"防控对策进行及时的开挖速率和支护措施动态调控,以尽可能避免岩爆的发生、降低岩爆发生的等级或延迟岩爆发生的时间。所建议的方法成功地应用于埋深1 900～2 525 m的锦屏二级水电站深埋引水隧洞和排水洞的施工开挖过程中,应用过程和结果验证了所建议方法的适用性。

深埋硬岩隧洞围岩的破坏模式分类与调控策略

根据锦屏II级水电站地下隧洞的地质条件、现场试验、数值分析和支护设计与施工全过程,建立深埋硬岩隧洞围岩的破坏模式分类方法。该分类方法依据支护要求和控制因素将深埋硬岩隧洞的破坏现象分为3个大类、9种典型破坏模式,分析各种破坏模式的发生机制、表现形态以及调控策略,重点讨论岩爆的机制以及相应的调控策略。应用该分类方法对锦屏II级水电站地下隧洞围岩的破坏模式进行识别、机制分析,相应的调控措施也得到采纳。工程实践表明,该分类方法全面、实用,为现场设计、地质和施工工程师等在深埋硬岩条件下进行隧洞开挖和支护设计优化提供具体指导方针。