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Sliding behaviors of the trapezoidal roof rock block under a lateral dynamic disturbance

Journal of Rock Mechanics and Geotechnical Engineering 2024年第3期16卷 741-760页

作者： Feng Dai Wancheng Zhu Min Ren Shunchuan Wu leilei niu Faculty of Land Resources Engineering Kunming University of Science and TechnologyKunming650093China Center for Rock Instability and Seismicity Research Department of Mining EngineeringSchool of Resource and Civil EngineeringNortheastern UniversityShenyang110819China

The surrounding rock of underground space is always affected by external dynamic disturbance from the side position,such as blasting vibration from a stope at the same level or seismic waves from adjacent strata.A series of laboratory tests,numerical simulations and theoretical analyses were carried out in this study to disclose the sliding mechanism of roof rock blocks under lateral ***,the experiments on trapezoidal key block under various clamping loads and disturbance were conducted,followed by numerical simulations using the fast Lagrangian analysis of continua(FLAC3D).Then,based on the conventional wave propagation model and the classical shear-slip constitutive model,a theoretical model was proposed to capture the relative displacement between blocks and the sliding displacement of the key *** results indicate that the sliding displacement of the key block increased linearly with the disturbance energy and decreased exponentially with the clamping load when the key block was disturbed to slide(without instability).Meanwhile,when the key block was disturbed to fall,two types of instability process may appear as immediate type or delayed *** addition,the propagation of stress waves in the block system exhibited obvious low-velocity and lowfrequency characteristics,resulting in the friction reduction effect appearing at the contact interface,which is the essential reason for the sliding of rock *** results can be applied to practical underground engineering and provide valuable guidance for the early detection and prevention of rockfalling disasters.

关键词： Lateral dynamic disturbance Trapezoidal rock block system Low-velocity and low-frequency wave Friction reduction effect Instability mode

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Numerical and theoretical study of load transfer behavior during cascading pillar failure

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第8期16卷 3014-3033页

作者： Hangyu Dong Wancheng Zhu leilei niu Chen Hou Xige Liu College of Geosciences and Engineering North China University of Water Resources and Electric PowerZhengzhou450046China Center for Rock Instability and Seismicity Research School of Resource and Civil EngineeringNortheastern UniversityShenyang110819China

To further study the load transfer mechanism of roofemulti-pillarefloor system during cascading pillar failure(CPF),numerical simulation and theoretical analysis were carried out to study the three CPF modes according to the previous experimental study on treble-pillar specimens,*** failure mode(SFM),domino failure mode(DFM)and compound failure mode(CFM).Based on the finite element code rock failure process analysis(RFPA^(2D)),numerical models of treble-pillar specimen with different mechanical properties were established to reproduce and verify the experimental results of the three CPF *** results show that the elastic rebound of roofefloor system induced by pillar instability causes dynamic disturbance to adjacent pillars,resulting in sudden load increases and sudden jump displacement of adjacent *** phenomena of load transfer in the roofemulti-pillarefloor system,as well as the induced accelerated damage behavior in adjacent pillars,were discovered and *** addition,based on the catastrophe theory and the proposed mechanical model of treble-pillar specimen edisc spring group system,a potential function that characterizes the evolution characteristics of roof emulti-pillarefloor system was *** analytical expressions of sudden jump and energy release of treble-pillar specimenedisc spring group system of the three CPF modes were derived according to the potential *** numerical and theoretical results show good agreement with the experimental *** study further reveals the physical essence of load transfer during CPF of roof emulti-pillarefloor system,which provides references for mine design,construction and disaster prevention.

关键词： Cascading pillar failure(CPF) Load transfer Multi-pillar Numerical simulation

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机械整流永磁发电机复合转子系统的动态特性研究

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西北工业大学学报 2024年第3期42卷 550-557页

作者：刘欣薛志伟张雨婷牛磊磊天津工业大学机械工程学院天津市现代机电装备技术重点实验室天津300387

机械整流永磁发电机的复合转子系统是该发电机实现整流功能的关键结构。研究该复合转子系统在双向输入工况下的动态特性,是为了分析该转子系统各构件在双向输入工况下的振动变形程度。基于集中质量参数理论,建立了复合转子系统在双向输... 详细信息

机械整流永磁发电机的复合转子系统是该发电机实现整流功能的关键结构。研究该复合转子系统在双向输入工况下的动态特性,是为了分析该转子系统各构件在双向输入工况下的振动变形程度。基于集中质量参数理论,建立了复合转子系统在双向输入工况下的动力学模型,通过龙格库塔法对该模型求解,得到了其在双向输入时各构件的动态特性。结果表明:复合转子系统各构件在双向输入时扭转振动位移波动幅值均在25μm左右,且各行星轮分路动态内外啮合力在双向输入时标准偏差均在200 N附近,即复合转子系统产生的振动程度相近;均载系数均随输入转矩增大而明显减小,在转矩达到500 N·m时趋于平缓,因此增大输入转矩能明显改善均载性能,使复合转子系统在双向输入工况下获得较好的动力学性能。研究结果对该发电机的减振降噪和可靠运行有重要意义。

关键词：机械整流永磁发电机复合转子系统集中质量参数动态特性

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样板支部创建视角的医学生党支部党建模式创新探索

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卫生职业教育 2024年第7期42卷 22-25页

作者：牛磊磊徐州医科大学江苏徐州221004

基于样板支部创建的视角,通过学思践悟、强基固本、铸魂赋能、守正创新四方面阐述医学生党支部积极创建学习教育的样板、规范建设的样板、人才培养的样板及特色品牌的样板的具体路径,并从系统思维、激励导向、创新理念三方面提出全国党... 详细信息

基于样板支部创建的视角,通过学思践悟、强基固本、铸魂赋能、守正创新四方面阐述医学生党支部积极创建学习教育的样板、规范建设的样板、人才培养的样板及特色品牌的样板的具体路径,并从系统思维、激励导向、创新理念三方面提出全国党建工作样板支部创建的工作反思启示。

关键词：样板支部党建医学生党支部

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Experimental and numerical evaluation on debonding of fully grouted rockbolt under pull‑out loading

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International Journal of Coal Science & Technology 2022年第1期9卷 84-98页

作者： Shuisheng Yu Wancheng Zhu leilei niu Center for Rock Instability and Seismicity Research Department of Mining EngineeringSchool of Resource and Civil EngineeringNortheastern UniversityShenyang 110819China School of Architectural Engineering Zhongyuan University of TechnologyZhengzhou 450007China

The axial loading in rockbolts changes due to stress redistribution and rheology in the country rock *** a change may lead to debonding at rockbolt to grout interface or rupture of the *** this study,based on laboratory experiments,ultrasonic guided wave propagation in fully grouted rockbolt under different pull-out loads was investigated in order to examine the resultant debonding of *** signals obtained from the ultrasonic monitoring during the pull-out test were processed using wavelet multi-scale analysis and frequency spectrum analysis,the signal amplitude and the amplitude ratio(Q)of low frequency to high frequency were defined to quantify the debonding of *** addition to the laboratory test,numerical simulation on the effect of the embedment lengths on ultrasonic guided wave propagation in rockbolt was conducted by using a damage-based model,and the debonding between rockbolt and cement mortar was numerically *** was confirmed that the ultrasonic guided wave propagation in rockbolt was very sensitive to the debonding because of pull-out load,therefore,the critical bond length could be calculated based on the propagation of guided wave in the grouted *** time domain,the signal amplitude in rockbolt increased with pull-out load from 0 to 100 kN until the completely debonding,thus quantifying the debonding under the different pull-out *** the frequency domain,as the Q value increased,the debonding length of rockbolt decreased *** numerical results confirmed that the guided wave propagation in the fully grouted rockbolt was effective in detecting and quantifying the debonding of rockbolt under pull-out load.

关键词： Fully grouted rockbolt Debonding Pull-out load Ultrasonic guided wave propagation

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Experimental and numerical simulation on the sliding process of roof rock blocks triggered by dynamic disturbance

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Underground Space 2023年第3期10卷 269-293页

作者： Feng Dai Wancheng Zhu Min Ren leilei niu Chen Hou Center for Rock Instability and Seismicity Research Department of Mining EngineeringSchool of Resources and Civil EngineeringNortheastern UniversityShenyang 110819China Faculty of Land Resources Engineering Kunming University of Science and TechnologyKunming 650093China

With the excavation of underground opening,the roof rock block may fall under external dynamic *** this paper,the roof rock mass was simplified as a rock block system composed of trapezoidal rock blocks.A series of experiments and numerical simulations were performed to study the sliding process of the key block under the horizontal static clamping load and vertical impact *** propagation of stress wave in the block system were captured and analyzed by using high-speed camera and digital image correlation *** results reveal that a pendulum-type wave was generated due to the propagation and superposition of stress waves in the block ***,the governing mechanism of the sliding displacement of the key block was clarified based on the propagation of incident stress waves or pendulum-type ***,it is found that the sliding distance of the key block decreases in a power function with the increasing friction coefficient,or decreases in a parabolic function with the increasing trapezoid internal ***,a case study on the roof block sliding of the roadway at a gold mine was conducted,and it is concluded that the sliding of the key block resulted from the coupled effects of"shear driving"and"low friction"driven by stress wave propagation,regardless of a single or multi-layer rock block *** results may provide technical guideline for preventing rock-falling accidents caused by blasting distur-bances in underground mining.

关键词： Roof rock block Sliding instability Dynamic disturbance Pendulum-type wave Digital image correlation technique Numerical simulation

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不同冻结状态下含单裂隙岩石动态抗拉特性研究

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有色金属（矿山部分） 2024年第4期76卷 124-132,141页

作者：骆柯牛雷雷朱万成王聪赵蔚东北大学资源与土木工程学院采矿工程系岩石破裂与失稳研究所沈阳110819

目的:为探明冻融和动态扰动双重作用对寒区露天矿边坡岩体稳定性的影响。方法:利用摆锤冲击加载SHPB试验系统研究干燥、饱水和冻结状态下完整、含预制单裂隙花岗岩的动态抗拉峰值载荷、加载速率敏感性及破坏模式;建立了含裂隙饱和动态... 详细信息

目的:为探明冻融和动态扰动双重作用对寒区露天矿边坡岩体稳定性的影响。方法:利用摆锤冲击加载SHPB试验系统研究干燥、饱水和冻结状态下完整、含预制单裂隙花岗岩的动态抗拉峰值载荷、加载速率敏感性及破坏模式;建立了含裂隙饱和动态巴西劈裂数值模型,并验证了模型正确性,模拟不同加载速率下裂隙充水饱和试样的破坏模式和强度率效应。结果:结果表明:相同加载速率下,冻结强度>干燥强度>饱水强度,完整试样强度大于含裂隙试样,预制裂隙降低了试样的强度;不同含水和冻结状态下试样的动态抗拉峰值载荷与加载速率呈正向幂函数关系,表现出加载速率强化效应,干燥、饱水、冻结状态下完整、含裂隙试样的DIF T增速分别为0.465、0.456、0.445和0.479、0.438、0.480,冻结强化动态强度,饱水弱化强度,预制裂隙放大了加载速率敏感性;裂隙充水会增大饱和试样的强度、裂纹扩展范围增大。结论:研究结果为揭示不同冻结状态下含单裂隙岩石动态破裂机理提供试验和模拟支撑。

关键词：冻结岩石 SHPB 动态巴西劈裂饱水裂隙裂纹扩展

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High-precision temperature retrieval algorithm and verification for mesospheric airglow spectrum photometer

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Science China Earth Sciences 2024年第5期67卷 1639-1651页

作者： Shuqi niu Haiyang GAO Zhaoai YAN Ke REN leilei KOU Baichuan JIANG Lingbin BU Key Open Laboratory of Aerosol and Cloud Precipitation of China Meteorological Administration Nanjing 210044China School of Atmospheric Physics Nanjing University of Information Science and TechnologyNanjing 210044China National Space Science Center Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100190China

Photometric technology,characterized by its compact structure and relatively high stability,finds wide application in measuring airglow *** instrumentation is anticipated to assume a pivotal role as the primary equipment for extensive network observations of middle and upper atmospheric temperatures in China,thereby providing crucial support for space environmental monitoring and atmospheric dynamic ***,susceptibility to various factors such as instrument inconsistency,variability in observation conditions,and alterations in the background atmospheric environment across different stations poses a challenge,potentially resulting in data inconsistencies in network *** response to these challenges,we propose a multiple-parameter iterative inversion(MPII)algorithm for temperature retrieval based on a mesospheric airglow spectrum photometer(MASP)developed by our research *** algorithm accurately identifies the center of the image circle,corrects image distortion,and thereby obtains an accurate synthetic spectrum reflective of actual *** encompasses five adjustable parameters:sky background light,atmospheric temperature,filter temperature,optical system focal length,and degree of synthetic spectrum *** to traditional methods,significant enhancements in the accuracy of the inverted temperature are *** validate the effectiveness of the MPII algorithm,we conducted combined active and passive remote sensing synchronous measurements using MASP in conjunction with a sodium fluorescence Doppler lidar developed by the National Space Science *** utilizing the lidar temperature as a reference,atmospheric background radiation is mitigated from the MASP data,and the temperature is inverted using the MPII *** analysis with the traditional method reveals that temperatures calculated by the MPII algorithm exhibit better consistency than those observed by the lidar.

关键词： Temperature inversion Airglow spectrum photometer Rotational spectral lines Sodium fluorescence Doppler lidar Comparative observations

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一种新型机械整流式转子永磁发电机结构及其电磁特性

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西安交通大学学报 2022年第12期56卷 86-96页

作者：刘欣牛磊磊王晓远天津工业大学现代机电装备技术重点实验室天津300387 天津大学电气自动化与信息工程学院天津300072

为了有效收集利用永磁发电机系统中的往复运动机械能量,提出了一种新型机械整流式转子永磁发电机结构。该结构是在其齿圈转子内部增设行星定轴传动系统,并选择滚珠丝杠作为该发电机的原动机,通过集成于定轴系统中的两个单向轴承的单向... 详细信息

为了有效收集利用永磁发电机系统中的往复运动机械能量,提出了一种新型机械整流式转子永磁发电机结构。该结构是在其齿圈转子内部增设行星定轴传动系统,并选择滚珠丝杠作为该发电机的原动机,通过集成于定轴系统中的两个单向轴承的单向锁止作用将输入端的双向直线运动转化为齿圈转子的单向旋转,实现机械整流功能。建立了发电机6极36槽物理模型,采用气隙相对磁导法对该模型在不同机电结构参数和丝杠往复运行工况下的电磁特性进行分析。仿真结果表明:所提发电机效率的变化幅度受永磁体结构参数、中心轮齿数和气隙长度变化的影响在10%以内,效果并不显著;在负载增至30Ω、丝杠往复速度为1 m/s和驱动力为100 N的工况下,所提发电机效率达到最高,接近于80%,且趋于稳定,相比于往复速度、驱动力分别为0.2 m/s、100 N以及1 m/s、500 N的工况,其效率分别提升了约26%、22%,且效率变化幅度受丝杠往复速度比变化减小了7.2%,受往复驱动力比变化减小了21.2%。结果表明,通过增大丝杠往复速度和负载电阻,同时减小其往复驱动力,不仅能够有效提高所提发电机对往复运动机械能量的利用效率,还能减弱丝杠往复速度比和往复驱动力比变化对其效率变化幅度产生的影响。

关键词：永磁发电机电磁特性往复运动单向轴承机械整流

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Design and Verification of Parallel Hip Exoskeleton Considering Output Torque Anisotropy

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Journal of Bionic Engineering 2024年第3期21卷 1305-1320页

作者： Jilong Xu Yunzhan niu Fucai Liu Engineering Research Center of the Ministry of Education for Intelligent Control System and Intelligent Equipment Yanshan UniversityQinhuangdao066004China Key Laboratory of Industrial Computer Control Engineering of Heibei Province Yanshan UniversityQinhuangdao066004China College of Mechanical Engineering Yanshan UniversityQinhuangdao066004China

In rehabilitation training,it is crucial to consider the compatibility between exoskeletons and human legs in ***,most exoskeletons today adopt an anthropomorphic serial structure,which results in rotational centers that are not precisely aligned with the center of the hip *** address this issue,we introduce a novel exoskeleton called the Parallel Hip Exoskeleton(PH-Exo)in this ***-Exo is meticulously designed based on the anisotropic law of output *** the friction of the drive components,a dynamic model of the human-machine complex is *** analysis demonstrates that PH-Exo not only exhibits outstanding torque performance but also achieves high controllability in both flexion/extension and adduction/abduction ***,a robust controller is designed to address model uncertainty,friction,and external *** experiments indicate that under the control of the robust controller,each motor achieves excellent tracking performance.

关键词： Hip exoskeleton Parallel mechanism Misalignment Anisotropy Output torque

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