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A novel method for simulating nuclear explosion with chemical explosion to form an approximate plane wave: Field test and numerical simulation

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2137-2153页

作者： Wei Ming Xiaojie Yang Yadong Mao Xiang Wang manchao he Zhigang Tao College of Civil and Architecture Engineering North China University of Science and TechnologyTangshan063210China State Key Laboratory for Tunnel Engineering China University of Mining and Technology-BeijingBeijing100083China School of Mechanics and Civil Engineering China University of Mining and Technology-BeijingBeijing100083China

A nuclear explosion in the rock mass medium can produce strong shock waves,seismic shocks,and other destructive effects,which can cause extreme damage to the underground protection infrastructures.With the increase in nuclear explosion power,underground protection engineering enabled by explosion-proof impact theory and technology ushered in a new challenge.This paper proposes to simulate nuclear explosion tests with on-site chemical explosion tests in the form of multi-hole explosions.First,the mechanism of using multi-hole simultaneous blasting to simulate a nuclear explosion to generate approximate plane waves was analyzed.The plane pressure curve at the vault of the underground protective tunnel under the action of the multi-hole simultaneous blasting was then obtained using the impact test in the rock mass at the site.According to the peak pressure at the vault plane,it was divided into three regions:the stress superposition region,the superposition region after surface reflection,and the approximate plane stress wave zone.A numerical simulation approach was developed using PFC and FLAC to study the peak particle velocity in the surrounding rock of the underground protective cave under the action of multi-hole blasting.The time-history curves of pressure and peak pressure partition obtained by the on-site multi-hole simultaneous blasting test and numerical simulation were compared and analyzed,to verify the correctness and rationality of the formation of an approximate plane wave in the simulated nuclear explosion.This comparison and analysis also provided a theoretical foundation and some research ideas for the ensuing study on the impact of a nuclear explosion.

关键词： Approximate plane wave Multi-hole simultaneous blasting Chemical explosion Nuclear explosion Pressure sensor inclusion

Experimental study on the effect of unloading rate on gneiss rockburst

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2064-2076页

作者： Dongqiao Liu Jie Sun Ran Li manchao he Binghao Cao Chongyuan Zhang Wen Meng State Key Laboratory for Tunnel Engineering China University of Mining and TechnologyBeijing100083China Key Laboratory of Active Tectonics and Geological Safety Ministry of Natural ResourcesInstitute of GeomechanicsChinese Academy of Geological SciencesBeijing100081China School of Mechanics and Civil Engineering China University of Mining and TechnologyBeijing100083China

Rockburst are often encountered in tunnel construction due to the complex geological conditions.To study the influence of unloading rate on rockburst,gneiss rockburst experiments were conducted under three groups of unloading rates.A high-speed photography system and acoustic emission(AE)system were used to monitor the entire process of rockburst process in real-time.The results show that the intensity of gneiss rockburst decreases with decrease of unloading rate,which is manifested as the reduction of AE energy and fragments ejection velocity.The mechanisms are proposed to explain this effect:(i)The reduction of unloading rate changes the crack propagation mechanism in the process of rockburst.This makes the rockbursts change from the tensile failure mechanism at high unloading rate to the tension-shear mixed failure mechanism at low unloading rate,and more energy released in the form of shear crack propagation.Then,less strain energy is converted into kinetic energy of fragments ejection.(ii)Less plate cracking degree of gneiss has taken shape due to decrease of unloading rate,resulting in the destruction of rockburst incubation process.The enlightenments of reducing the unloading rate for the project are also described quantitatively.The rockburst magnitude is reduced from the medium magnitude at the unloading rate of 0.1 MPa/s to the slight magnitude at the unloading rate of 0.025 MPa/s,which was judged by the ejection velocity.

关键词： Rockburst Unloading rate Crack propagation Influence mechanisms

Digital monitoring of rotary-percussive drilling with down-the-hole hammer for profiling weathered granitic ground

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第5期16卷 1615-1636页

作者： Wendal Victor Yue Siyuan Wu manchao he Yafei Qiao Zhongqi Quentin Yue Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai200092China Department of Civil Engineering Faculty of EngineeringThe University of Hong KongPokfulam RoadHong KongChina State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyBeijing100083China Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji UniversityShanghai200092China

Rock and geotechnical engineering investigations involve drilling holes in ground with or without retrieving soil and rock samples to construct the subsurface ground profile.On the basis of an actual soil nailing drilling for a slope stability project in Hong Kong,this paper further develops the drilling process monitoring(DPM)method for digitally profiling the subsurface geomaterials of weathered granitic rocks using a compressed airflow driven percussive-rotary drilling machine with down-the-hole(DTH)hammer.Seven transducers are installed on the drilling machine and record the chuck displacement,DTH rotational speed,and five pressures from five compressed airflows in real-time series.The mechanism and operations of the drilling machine are elaborated in detail,which is essential for understanding and evaluating the drilling data.A MATLAB program is developed to automatically filter the recorded drilling data in time series and classify them into different drilling processes in sub-time series.These processes include penetration,push-in with or without rod,pull-back with or without rod,rod-tightening and rod-untightening.The drilling data are further reconstructed to plot the curve of drill-bit depth versus the net drilling time along each of the six drillholes.Each curve is found to contain multiple linear segments with a constant penetration rate,which implies a zone of homogenous geomaterial with different weathering grades.The effect from fluctuation of the applied pressures is evaluated quantitatively.Detailed analyses are presented for accurately assess and verify the underground profiling and strength in weathered granitic rock,which provided the basis of using DPM method to confidently assess drilling measurements to interpret the subsurface profile in real time.

关键词： Drilling process monitoring(DPM) Down-the-hole(DTH)hammer Percussive-rotary drilling Weathering granitic rocks

开挖补偿法防控深部地下岩爆灾害——引汉济渭工程秦岭输水隧洞案例分析

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Engineering 2024年第3期34卷 154-163页

作者： Jie Hu manchao he Hongru Li Zhigang Tao Dongqiao Liu Tai Cheng Di Peng Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai 200092China State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyBeijing 100083China

Rockburst disasters occur frequently during deep underground excavation,yet traditional concepts and methods can hardly meet the requirements for support under high geo-stress conditions.Consequently,rockburst control remains challenging in the engineering field.In this study,the mechanism of excavation-induced rockburst was briefly described,and it was proposed to apply the excavation compensation method(ECM)to rockburst control.Moreover,a field test was carried out on the Qinling Water Conveyance Tunnel.The following beneficial findings were obtained:Excavation leads to changes in the engineering stress state of surrounding rock and results in the generation of excess energy DE,which is the fundamental cause of rockburst.The ECM,which aims to offset the deep excavation effect and lower the risk of rockburst,is an active support strategy based on high pre-stress compensation.The new negative Poisson’s ratio(NPR)bolt developed has the mechanical characteristics of high strength,high toughness,and impact resistance,serving as the material basis for the ECM.The field test results reveal that the ECM and the NPR bolt succeed in controlling rockburst disasters effectively.The research results are expected to provide guidance for rockburst support in deep underground projects such as Sichuan-Xizang Railway.

关键词： Rockburst Excavation compensation method Pre-stressed support Negative Poisson’s ratio bolt Tunnel boring machine

Mechanism of high-preload support based on the NPR anchor cable in layered soft rock tunnels

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Journal of Mountain Science 2024年第4期21卷 1403-1418页

作者： SUI Qiru he manchao SHI Mengfan TAO Zhigang ZHAO Feifei ZHANG Xiaoyu State Key Laboratory for Tunnel Engineering China University of Mining and Technology(Beijing)Beijing 100083China School of Mechanics and Civil Engineering China University of Mining and Technology(Beijing)Beijing 100083China

The control of large deformation problems in layered soft rock tunnels needs to solve urgently.The roof problem is particularly severe among the deformation issues in tunnels.This study first analyzes the asymmetric deformation modes in layered soft rock tunnels with large deformations.Subsequently,we construct a mechanical model under ideal conditions for controlling the roof of layered soft rock tunnels through high preload with the support of NPR anchor cables.The prominent roles of long and short NPR anchor cables in the support system are also analyzed.The results indicate the significance of high preload in controlling the roof of layered soft rock tunnels.The short NPR anchor cables effectively improve the integrity of the stratified soft rock layers,while the long NPR anchor cables effectively mobilize the self-bearing capacity of deep-stable rock layers.Finally,the high-preload support method with NPR anchor cables is validated to have a good effect on controlling large deformations in layered soft rock tunnels through field monitoring data.

关键词： Tunnel engineering Soft rock High-preload support NPR anchor cables

Rock dynamics in deep mining

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International Journal of Mining Science and Technology 2023年第9期33卷 1065-1082页

作者： manchao he Qi Wang State Key Laboratory for Geo-mechanics and Deep Underground Engineering China University of Mining&Technology-BeijingBeijing 100083China

Rock mass dynamics disasters caused by excavations and mining occur frequently in deep mines.In order to establish a theoretical system and control technologies for such disasters,we first classify and define dynamic disasters,such as rock bursts,coal bursts,mine pressure bumps,and mine earthquakes.According to the occurrence mechanism of different types of dynamic disasters,we establish a compensation control theory based on excavation and mining effects.On the basis,we propose three key technologies:high prestress compensation technology for the roadway,pressure relief technology using directional roof cutting,and the goaf filling technology using broken rock dilation.These three technologies constitute the compensation control method for dynamic disasters in deep mines.Finally,this method was successfully applied in a deep coal mine with high stress,with monitored results suggesting its rationality.This work provides a new concept and control method for the prevention of rock dynamic disasters in deep mines.

关键词： Rock burst Coal burst Mine pressure bump Mine earthquake Excavation compensation control Mining compensation control

Dynamic response mechanism and precursor characteristics of gneiss rockburst under different initial burial depths

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Journal of Mountain Science 2024年第3期21卷 1004-1018页

作者： LIU Dongqiao SUN Jie MENG Wen he manchao ZHANG Chongyuan LI Ran CAO Binghao State Key Laboratory for Tunnel Engineering China University of Mining and TechnologyBeijing 100083China Key Laboratory of Active Tectonics and Geological Safety Ministry of Natural ResourcesInstitute of GeomechanicsChinese Academy of Geological SciencesBeijing 100081China School of Mechanics and Civil Engineering China University of Mining and TechnologyBeijing 100083China

To investigate the influence mechanism of geostress on rockburst characteristics,three groups of gneiss rockburst experiments were conducted under different initial geostress conditions.A high-speed photography system and acoustic emission(AE)monitoring system were used to monitor the entire rockburst process in real time.The experimental results show that when the initial burial depth increases from 928 m to 1320 m,the proportion of large fracture scale in rockburst increases by 154.54%,and the AE energy increases by 565.63%,reflecting that the degree and severity of rockburst increase with the increase of burial depth.And then,two mechanisms are proposed to explain this effect,including(i)the increase of initial geostress improves the energy storage capacity of gneiss,and then,the excess energy which can be converted into kinetic energy of debris ejection increases,consequently,a more pronounced violent ejection phenomenon is observed at rockburst;(ii)the increase of initial geostress causes more sufficient plate cracks of gneiss after unloading ofσh,which provides a basis for more severe ejection of rockburst.What’s more,a precursor with clear physical meaning for rockburst is proposed under the framework of dynamic response process of crack evolution.Finally,potential value in long term rockburst warning of the precursor obtained in this study is shown via the comparison of conventional precursor.

关键词： Traffic Engineering Gneiss Rockburst Crack propagation Excess energy Precursor characteristic

Excavation compensation theory and supplementary technology system for large deformation disasters

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Deep Underground Science and Engineering 2023年第2期2卷 105-128页

作者： manchao he Qiru Sui Zhigang Tao State Key Laboratory for GeoMechanics and Deep Underground Engineering China University of Mining and Technology(Beijing)BeijingChina School of Mechanics and Civil Engineering China University of Mining and Technology(Beijing)BeijingChina Institute for Deep Underground Science and Engineering China University of Mining and Technology(Beijing)BeijingChina

Given the challenges in managing large deformation disasters in energy engineering,traffic tunnel engineering,and slope engineering,the excavation compensation theory has been proposed for large deformation disasters and the supplementary technology system is developed accordingly.This theory is based on the concept that“all destructive behaviors in tunnel engineering originate from excavation.”This paper summarizes the development of the excavation compensation theory in five aspects:the“theory,”“equipment,”“technology,”the design method with large deformation mechanics,and engineering applications.First,the calculation method for compensation force has been developed based on this theory,and a comprehensive large deformation disaster control theory system is formed.Second,a negative Poisson's ratio anchor cable with high preload,large deformation,and super energy absorption characteristics has been independently developed and applied to large deformation disaster control.An intelligent tunnel monitoring and early warning cloud platform system are established for remote monitoring and early warning system of Newton force in landslide geological hazards.Third,the double gradient advance grouting technology,the two-dimensional blasting technology,and the integrated Newton force monitoring--early warning--control technology are developed for different engineering environments.Finally,some applications of this theory in China's energy,traffic tunnels,landslide,and other field projects have been analyzed,which successfully demonstrates the capability of this theory in large deformation disaster control.

关键词： energy engineering excavation compensation large deformation NPR anchor cable slope engineering traffic tunnel engineering

Instability mechanism of mining roadway passing through fault at different angles in kilometre-deep mine and control measures of roof cutting and NPR cables

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Journal of Mountain Science 2024年第1期21卷 236-251页

作者： SUN Xiaoming WANG Jian ZHAO Wenchao MING Jiang ZHANG Yong LI Zhihu MIAO Chengyu GUO Zhibiao he manchao State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and Technology(Beijing)Beijing 100083China School of Mechanics and Civil Engineering China University of Mining and Technology(Beijing)Beijing 100083China

The angle α between the fault strike and the axial direction of the roadway produces different damage characteristics. In this paper, the research methodology includes theoretical analyses, numerical simulations and field experiments in the context of the Daqiang coal mine located in Shenyang, China. The stability control countermeasure of "pre-splitting cutting roof + NPR anchor cable"(PSCR-NPR) is simultaneously proposed. According to the different deformation characteristics of the roadway, the faults are innovatively classified into three types, with α of type I being 0°-30°, α of type II being 30°-60°, and α of type III being 60°-90°. The full-cycle stress evolution paths during mining roadway traverses across different types of faults are investigated by numerical simulation. Different pinch angles α lead to high stress concentration areas at different locations in the surrounding rock. The non-uniform stress field formed in the shallow surrounding rock is an important reason for the instability of the roadway. The pre-cracked cut top shifted the high stress region to the deep rock mass and formed a low stress region in the shallow rock mass. The high prestressing NPR anchor cable transforms the non-uniform stress field of the shallow surrounding rock into a uniform stress field. PSCR-NPR is applied in the fault-through roadway of Daqiang mine. The low stress area of the surrounding rock was enlarged by 3-7 times, and the cumulative convergence was reduced by 45%-50%. It provides a reference for the stability control of the deep fault-through mining roadway.

关键词： Kilometre-deep mine Fault Mining roadway Failure mechanism Pre-splitting cutting roof High pre-stress NPR anchor cable