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Non-destructive testing and pre-warning analysis on the quality of bolt support in deep roadways of mining districts

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International Journal of Mining Science and Technology 2017年第6期27卷 989-998页

作者： Zhang Houquan Miao Xiexing Zhang Guimin Wu Yu chen yanlong State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and Technology Xuzhou 221116 China School of Mechanics and Civil Engineering China University of Mining and Technology Xuzhou 221116 China

The bolt support quality of coal roadways is one of the important factors for the efficiency and security of coal production. By means of a self-developed technique and equipment of random non-destructive testing, non-destructive detection and pre-warning analysis on the quality of bolt support in deep roadways of mining districts were performed in a number of mining areas. The measured data were obtained in the detection instances of abnormal in-situ stress and support invalidation etc. The corresponding relation between axial bolt load variation and roadway surrounding rock deformation and stability was summarized in different mining service stages. Pre-warning technology of roadway surrounding rock stability is proposed based on the detection of axial bolt load. Meanwhile, pre-warning indicators of axial bolt load in different mining service stages are offered and some successful pre-warning cases are also *** research results show that the change rules of axial bolt load in different mining service stages are quite similar in different mining areas. The change of axial bolt load is in accord with the adjustment of surrounding rock stress, which can consequently reflect the deformation and stability state of roadway surrounding rock. Through the detection of axial bolt load in different sections of roadways, the status of real-time bolt support quality can be reflected; meanwhile, the rationality of bolt support design can be evaluated which provides reference for bolting parameters optimization.

关键词： Deep roadways Bolt support quality Random nondestructive testing Surrounding rock stability Prediction and pre-warning

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Stability analysis of rib pillars in highwall mining under dynamic and static loads in open‑pit coal mine

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International Journal of Coal Science & Technology 2022年第3期9卷 120-135页

作者： Haoshuai Wu yanlong chen Haoyan Lv Qihang Xie Yuanguang chen Jun Gu State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyXuzhou 221116China School of Mechanics and Civil Engineering China University of Mining and TechnologyXuzhou 221116China

The retained coal in the end slope of an open-pit mine can be mined by the highwall mining ***,the instability mechanism of the reserved rib pillar under dynamic loads of mining haul trucks and static loads of the overlying strata is not clear,which restricts the safe and efcient application of highwall *** this study,the load-bearing model of the rib pillar in highwall mining was established,the cusp catastrophe theory and the safety coefcient of the rib pillar were considered,and the criterion equations of the rib pillar stability were *** on the limit equilibrium theory,the limit stress of the rib pillar was analyzed,and the calculation equations of plastic zone width of the rib pillar in highwall mining were *** on the Winkler foundation beam theory,the elastic foundation beam model composed of the rib pillar and roof under the highwall mining was established,and the calculation equations for the compression of the rib pillar under dynamic and static loads were *** results showed that with the increase of the rib pillar width,the total compression of the rib pillar under dynamic and static loads decreases nonlinearly,and the compression of the rib pillar caused by static loads of the overlying strata and trucks has a decisive *** simulation and theoretical calculation were also performed in this *** the numerical simulation,the coal seam with a buried depth of 122 m and a thickness of 3 m is mined by highwall mining *** to the established rib pillar instability model of the highwall mining system,it is found that when the mining opening width is 3 m,the reasonable width of the rib pillar is at least 1.3 m,and the safety factor of the rib pillar is *** numerical simulation results are in good agreement with the results of theoretical calculation,which verifes the feasibility of the theoretical analysis of the rib pillar *** research provides a reference for the st

关键词： Open-pit coal mine Dynamic and static loads Highwall mining Rib pillar Catastrophe instability

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Bolt-grouting combined support technology in deep soft rock roadway

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International Journal of Mining Science and Technology 2016年第5期26卷 777-785页

作者： chen yanlong Meng Qingbin Xu Guang Wu Haoshuai Zhang Guimin State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining & Technology Department of Mining Engineering & Metallurgical Engineering Western Australian School of Mines Curtin University School of Mechanics and Civil Engineering China University of Mining & Technology

Analyzing the mineral composition, mechanical properties and ground stress testing in surrounding rock,the study investigated the failure mechanism of deep soft rock roadway with high stress. The boltgrouting combined support system was proposed to prevent such failures. By means of FLAC3D numerical simulation and similar material simulation, the feasibility of the support design and the effectiveness of support parameters were discussed. According to the monitoring the surface and deep displacement in surrounding rock as well as bolt axial load, this paper analyzed the deformation of surrounding rock and the stress condition of the support structure. The monitor results were used to optimize the proposed support scheme. The results of field monitors demonstrate that the bolt-grouting combined support technology could improve the surround rock strength and bearing capacity of support structure, which controlled the great deformation failure and rheological property effectively in deep soft rock roadway with high stress. As a result, the long term stability and safety are guaranteed.

关键词： Deep soft rock roadway Bolt-grouting support Numerical simulation Similar material simulation High stress

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Numerical modeling on strain energy evolution in rock system interaction with energy-absorbing prop and rock bolt

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International Journal of Mining Science and Technology 2023年第10期33卷 1273-1288页

作者： Yang Hao Chunhui Liu Yu Wu Hai Pu yanlong chen Lingling Shen Guichen Li State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering China University of Mining and TechnologyXuzhou 221116China School of Mechanics and Civil Engineering China University of Mining and TechnologyXuzhou 221116China School of Mines China University of Mining and TechnologyXuzhou 221116China

The interaction mechanism between coal and rock masses with supporting materials is significant in roadway control, especially in deep underground mining situations where dynamic hazards frequently happened due to high geo-stress and strong disturbed effects. This paper is to investigate the strain energy evolution in the interaction between coal and rock masses with self-designed energy-absorbing props and rock bolts by numerical modeling with the finite difference method. The interaction between rock and rock bolt/prop is accomplished by the cables element and the interface between the inner and outer props. Roadway excavation and coal extraction conditions in deep mining are numerically employed to investigate deformation, plastic zone ranges, strain energy input, accumulation, dissipation,and release. The effect on strain energy input, accumulation, dissipation, and release with rock deformation, and the plastic zone is addressed. A ratio of strain energy accumulation, dissipation, and release with energy input a, β, γ is to assess the dynamic hazards. The effects on roadway excavation and coal extraction steps of a, β, γ are discussed. The results show that:(1) In deep high geo-stress roadways, the energyabsorbing support system plays a dual role in resisting deformation and reducing the scope of plastic zones in surrounding rock, as well as absorbing energy release in the surrounding rock, especially in the coal extraction state to mitigate disturbed effects.(2) The strain energy input, accumulation is dependent on roadway deformation, the strain energy dissipation is relied on plastic zone area and disturbed effects, and strain energy release density is the difference among the three. The function of energyabsorbing rock bolts and props play a key role to mitigate strain energy release density and amount, especially in coal extraction condition, with a peak density value from 4×10^(4) to 1×10^(4)J/m^(3), and amount value from 3.57×10^(8) to 1.90×10^(6)J.(3) W

关键词： Strain energy Coal and rock mass Energy-absorbing prop and rock bolt Strain energy evolution

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Stability analysis of a slope containing water-sensitive mudstone considering different rainfall conditions at an open-pit mine

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International Journal of Coal Science & Technology 2023年第4期10卷 233-253页

作者： Guoyu Yang yanlong chen Xuanyu Liu Ri Yang Yafei Zhang Jialong Zhang State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyXuzhou 221116China School of Mines China University of Mining and TechnologyXuzhou 221116China Harwusu Open-Pit Mine China Shenhua Energy Co.LtdOrdos 010300China China Energy Investment Beidian Shengli Energy Co. LtdXinlinhot 026000China School of Mechanics and Civil Engineering China University of Mining and TechnologyXuzhou 221116China

Mudstone, as a typical soft rock with wide distribution, has been endangering the slopes containing mudstone by its watersensitivity of swelling and weakening strength when encountering water. To comprehensively understand the water-sensitivity of mudstone and reveal its infuence on slope stability, we took the working slope containing water-sensitive mudstone of Shengli No.1 open-pit coal mine in Xilinhot, Inner Mongolia, China, as an example. Mudstone samples taken from the working slope were remodeled and saturated, and then triaxial tested to obtain the efective cohesion and efective internal friction angle. The flter paper method was used to obtain the soil–water characteristic curve of unsaturated mudstone. The pore structure of mudstone samples with diferent water contents were analyzed using the mercury intrusion porosimetry tests combined with the fractal dimension. The total pore content of the mudstone sample with lower water content is greater than that of the mudstone sample with higher water content. The mesopores are more in the mudstone sample with lower water content, while the small pores are more in the mudstone sample with higher water content. The variation of water content will change the complexity of mudstone pore structure. The higher the water content, the simpler the mudstone pore structure and the smoother the pore surface. Numerical calculations were conducted on the stability of the working slope under diferent rainfall conditions. The efective saturation on the mudstone layer surface changed and the plastic strain all occurred on the mudstone steps under diferent rainfall conditions. The key to preventing landslide of the slope containing water-sensitive mudstone in Shengli No.1 open-pit coal mine is to control the deformation and sliding of the mudstone layer.

关键词： Water-sensitivity SWCC Pore structure Rainfall infltration Slope stability

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Chlorophyll Fluorescence Extraction from Water-Leaving Radiance of Algae-Containing Water Through Polarization

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Journal of Ocean University of China 2017年第6期16卷 1003-1008页

作者： WANG Lin QIU Zhongfeng PANG Huifang LIU Yongjian chen yanlong JIANG Lingling Department of Ocean Remote Sensing National Marine Environmental Monitoring Center School of Marine Sciences Nanjing University of Information Science and Technology College of Environmental Science and Engineering Dalian Maritime University

When measuring reflectance spectra, it is very important to accurately extract chlorophyll fluorescence from elastic-scattering light in water-leaving radiance. The elastic scattering of light by water particles produces partially polarized light. In contrast, chlorophyll fluorescence in planktonic algae yields completely unpolarized light. These properties can be used to separate fluorescent signals from the water-leaving radiance and thus to determine chlorophyll concentration. The algal species Aureococcus anophagefferens was used to conduct a laboratory polarization experiment. For the tests, we used a field spectroradiometer and a polarizer; measurements were collected using two different observation modes. The chlorophyll fluorescence curve extracted through polarization shows an excellent match with the results obtained using the fluorospectro photometer for both measurement modes, suggesting that polarization-based chlorophyll fluorescence extraction may be feasible. The extracted fluorescence is more reliable at incident zenith angles ranging from 30? to 60?. For algae-containing water, the results improve with increasing chlorophyll concentration. This method could help improve chlorophyll concentration measurement and the remote-sensing detection of resulting harmful algae blooms.

关键词： chlorophyll fluorescence polarization technique water-leaving radiance extraction red shift

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Zonal extraction technology and numerical simulation analysis in open pit coal mine

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International Journal of Mining Science and Technology 2012年第4期22卷 487-491页

作者： chen yanlong Cai Qingxiang Shang Tao Peng Hongge Zhou Wei chen Shuzhao School of Mines China University of Mining&TechnologyXuzhou 221116China Department of Earth Resources Engineering Faculty of EngineeringKyushu UniversityFukuoka 819-0395Japan

In order to enhance coal recovery ratio of open pit coal mines, a new extraction method called zonal mining system for residual coal around the end-walls is presented. The mining system can improve economic benefits by exploiting haulage and ventilation roadways from the exposed position of coal seams by uti- lizing the existing transportation systems. Moreover, the main mining parameters have also been dis- cussed. The outcome shows that the load on coal seam roof is about 0.307 MPa and the drop step of the coal seam roof about 20.3 m when the thickness of cover and average volume weight are about 120 m and 0.023 MN/m~ respectively. With the increase of mining height and width, the coal recovery ratio can be improved. However, when recovery ratio is more than 0.85, the average stress on the coal pillar will increase tempestuously, so the recovery ratio should also be controlled to make the coal seam roof safe. Based on the numerical simulation results, it is concluded that the ratio of coal pillar width to height should be more than 1.0 to make sure the coal pillars are steady, and there are only minor dis- placements on the end-walls.

关键词： Extraction technologyNumerical simulationZonal miningResidual coalEnd-walls

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A fast,edge-preserving,distance-regularized model with bilateral filtering for oil spill segmentation of SAR images

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Journal of Oceanology and Limnology 2021年第4期39卷 1198-1210页

作者： Wandi WANG Hui SHENG yanlong chen Shanwei LIU Jijun MAO Zhe ZENG Jianhua WAN China University of Petroleum Qingdao 266580China National Marine Environmental Monitoring Centre Dalian 116023China Surveying and Mapping Institute of Shandong Province Jinan 250102China

Marine oil spills are among the most significant sources of marine *** aperture radar(SAR)has been used to improve oil spill observations because of its advantages in oil spill detection and ***,speckle noise,weak boundaries,and intensity inhomogeneity often exist in the oil spill regions of SAR imagery,which will seriously aff ect the accurate identification of oil *** enhance marine oil spill segmentation of SAR images,a fast,edge-preserving framework based on the distance-regularized level set evolution(DRLSE)model was ***,a bilateral filter penalty term is designed and incorporated into the DRLSE energy function(BF-DRLSE)to preserve the edges of oil spills,and an adaptive initial box boundary was selected for the DRLSE model to reduce the operation time *** sets of RadarSat-2 SAR data were used to test the proposed *** experimental results indicate that the bilateral filtering scheme incorporated into the energy function during level set evolution improved the stability of level set *** with other methods,the proposed improved BF-DRLSE algorithm displayed a higher overall segmentation accuracy(97.83%).In addition,using an appropriate initial box boundary for the DRLSE method accelerated the global search process,improved the accuracy of oil spill segmentation,and reduced computational ***,the results suggest that the proposed framework is eff ective and applicable for marine oil spill segmentation.

关键词： level sets bilateral filter marine oil spill segmentation synthetic aperture radar(SAR)imagery

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Validation of MODIS ocean-colour products in the coastal waters of the Yellow Sea and East China Sea

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Acta Oceanologica Sinica 2020年第1期39卷 91-101页

作者： Lingling Jiang Xiangyu Guo Lin Wang Shubha Sathyendranath Hayley Evers-King yanlong chen Bingnan Li College of Environmental Science and Engineering Dalian Maritime UniversityDalian 116026China Ministry of Ecology Environment National Marine Environmental Monitoring CenterDalian 116023China Plymouth Marine Laboratory(PML) PlymouthDevonPL13DHUK

An extensive study collected in situ data along the Yellow Sea(YS) and East China Sea(ECS) to assess the radiometric properties and the concentration of the water constituents derived from Moderate Resolution Imaging Spectroradiometer(MODIS). Thirteen high quality match-ups were obtained for evaluating the MODIS estimates of Rrs(λ), chlorophyll a(Chl a) and concentrations of suspended particulate sediment matter(SPM). For MODIS Rrs(λ), the mean absolute percentage difference(APD) was in the range of 20%–36%, and the highest uncertainty appeared at 412 nm, whereas the band ratio of Rrs(λ) at 488 nm compared with that at 547 nm was highly consistent, with an APD of 7%. A combination of near-infrared bands and shortwave infrared wavelengths atmosphere correction algorithm(NIR-SWIR algorithm) was applied to the MODIS data, and the estimation accuracy of Rrs were improved at most of the visible spectral bands except 645 nm, 667 nm and 678 nm. Two ocean-colour empirical algorithms for Chl a estimation were applied to the processed data, the results indicated that the accuracy of the derived Chl a values was obviously improved, the four-band algorithms outperformed the other algorithm for measured and simulated datasets, and the minimum APD was 35%. The SPM was also quantified. Two regional and two coastal SPM algorithms were modified according to the in situ data. By comparison, the modified Tassan model had a higher accuracy for the application along the YS and ECS with an APD of 21%. However, given the limited match-up dataset and the potential influence of the aerosol properties on atmosphere correction, further research is required to develop additional algorithms especially for the low Chl a coastal water.

关键词： MODIS turbid waters chlorophyll a SPM retrieval algorithms Yellow and East China Sea

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Influence of dynamic pressure on deep underground soft rock roadway support and its application

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International Journal of Mining Science and Technology 2016年第5期26卷 903-912页

作者： Meng Qingbin Han Lijun chen yanlong Fan Jiadong Wen Shengyong Yu Liyuan Li Hao State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining & Technology Shandong Provincial Key Laboratory of Depositional Mineralization & Sedimentary Minerals Shangdong University of Science & Technology

Due to high ground stress and mining disturbance, the deformation and failure of deep soft rock roadway is serious, and invalidation of the anchor net-anchor cable supporting structure occurs. The failure characteristics of roadways revealed with the help of the ground pressure monitoring. Theoretical analysis was adopted to analyze the influence of mining disturbance on stress distribution in surrounding rock,and the change of stress was also calculated. Considering the change of stress in surrounding rock of bottom extraction roadway, the displacement, plastic zone and distribution law of principal stress difference under different support schemes were studied by means of FLAC3D. The supporting scheme of U-shaped steel was proposed for bottom extraction roadway that underwent mining disturbance. We carried out a similarity model test to verify the effect of support in dynamic pressure. Monitoring results demonstrated the change rules of deformation and stress of surrounding rock in different supporting schemes. The supporting scheme of U-shaped steel had an effective control on deformation of surrounding rock. The scheme was successfully applied in underground engineering practice, and achieved good technical and economic benefits.

关键词： Deep soft rock roadway Dynamic pressure impact Similarity model test Combined support Ground pressure monitoring

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