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A stability evaluation method for deep-seated toppling in the upper Lancang river,Southwestern China

Journal of Rock Mechanics and Geotechnical engineering 2024年第7期16卷 2388-2410页

作者： Yibing Ning Huiming Tang Jianbing Peng Yanjun Shen John V.Smith Bocheng Zhang college of Geological engineering and geomatics Chang’an UniversityXi’an710054China Academy of Yellow River Sciences of Shaanxi Province Chang’an UniversityXi’an710054China Badong National Observation and Research Station of Geohazards China University of GeosciencesWuhan430074China School of engineering RMIT UniversityMelbourne3001Australia

Deep-seated toppling in the upper reaches of the Lancang River,southwest China involves deformations exceeding 100 m in *** slope deformation is initiated by river downcutting and evolves distinctive characteristics with a depth of river *** this study,we propose a system for evaluating the stability of deep-seated toppled slopes in different evolutionary *** system contains identification criteria for each evolutionary stage and provides the corresponding stability evaluation *** on the mechanical and kinematic analysis of slope blocks,the specific stage of slope movement can be identified in the field through outcrop mapping,in situ tests,surface displacement monitoring,and adit and borehole *** stability evaluation methods are established based on the limiting equilibrium theory and the strain compatibility between the undisturbed zone and the toppled ***,several sample slopes in different evolution stages have been investigated to verify the applicability and accuracy of the proposed stability evaluation *** results indicate that intense tectonic activity and rapid river incision lead to a maximum principal stress ratio exceeding 10 near the slope surface,thus triggering widespread toppling deformations along the river *** considering the losses of joint cohesion during the further rotation process,the safety factor of the slope drops by 7%e28%.The self-stabilization of toppling deformation can be recognized by the layer symmetry configuration after the free rotation of the deflected *** toppled rock blocks mainly suffer sliding failures beyond the layer symmetry *** factor of safety of the K73 rockslide decreased from 1.17 to 0.87 by considering the development of the potential sliding surface and the toesaturated zone.

关键词： Stability evaluation Deep-seated toppling Evolutionary process Reservoir impoundment Rock slope

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深部多形式应用交岔点围岩失稳机理及能量演化研究

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Journal of Central South University 2024年第3期31卷 890-911页

作者：武毅艺何满潮李辉高玉兵谢生荣 college of Construction engineering Jilin UniversityChangchun 130026China School of Energy and mining engineering China University of Mining and Technology(Beijing)Beijing 100083China State Key Laboratory for Tunnel engineering Beijing 100083China

随着采矿进入深部地层,具有长服务年限的各类巷道交岔点围岩发生强烈破坏,需要明晰深部环境下交岔点围岩失效机理,以针对性地指导修复和补强作业。通过对多地矿井交岔点维护情况的调研,全面总结了连接型、交岔型、分岔型和旋岔型(环三角... 详细信息

随着采矿进入深部地层,具有长服务年限的各类巷道交岔点围岩发生强烈破坏,需要明晰深部环境下交岔点围岩失效机理,以针对性地指导修复和补强作业。通过对多地矿井交岔点维护情况的调研,全面总结了连接型、交岔型、分岔型和旋岔型(环三角柱)四类16种交岔点类型,提出了三类交岔点的典型应用形式:单一大型交岔点、嵌套式两交岔点组和环三角岩柱式交岔点群。将现场交岔点的破坏情况分为围岩局部破坏、三角岩柱破坏和整体性破坏的三种级别,从灾害的诱因和来源上,提出了外部环境因素、自身结构属性和人为设计隐患的三类13种致灾因素,并详述了各种致灾因素的致灾路径。建立了三类典型应用形式下交岔点的精细化模型,对数值软件进行二次开发,引入了畸变能密度指标进行围岩的能量分析。研究表明,交岔点围岩的畸变能峰值在三角区岩柱内,增高系数在2.5左右。最大断面处围岩畸变能同样发生积聚,增高系数在1.5左右。因此,提出了交岔点的修复需以强化三角岩柱和大断面处围岩为重点,并对深井交岔点的修复提出了以三角岩柱和大断面段补强为主的针对性方案。本研究为深部交岔点的破坏因素分析、数值模拟指标引入和修复支护提供了参考。

关键词：巷道交岔点围岩失稳应用形式精细化模型畸变能密度

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Mechanical properties and damage evolution characteristics of waste tire steel fiber-modified cemented paste backfill

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International Journal of mining Science and Technology 2024年第7期34卷 909-924页

作者： Shenggen Cao Chiyuan Che Yun Zhang Changhao Shan Yang Liu Changzheng Zhao Shuyu Du State Key Laboratory for Fine Exploration and Intelligent Development of Coal Resources School of MinesChina University of Mining and TechnologyXuzhou 221116China college of Energy engineering Xi’an University of Science&TechnologyXi’an 710054China

During the process of constructional backfill mining,the cemented paste backfill(CPB)typically exhibits a high degree of brittleness and limited resistance to *** this study,the mechanical and damage evolution characteristics of waste tire steel fiber(WTSF)-modified CPB were studied through uniaxial compression tests,acoustic emission(AE)tests,and scanning electron microscopy(SEM).The results showed that the uniaxial compressive strength(UCS)decreased when the WTSF content was 0.5%,1%,and 1.5%.When the WTSF content reached 1%,the UCS of the modified CPB exhibited a minimal decrease(0.37 MPa)compared to that without *** the WTSF content was 0.5%,1%,and 1.5%,peak strain of the WTSF-modified CPB increased by 18%,31.33%,and 81.33%,while the elastic modulus decreased by 21.31%,26.21%,and 45.42%,*** addition of WTSF enhances the activity of AE events in the modified CPB,resulting in a slower progression of the entire failure *** the failure,the modified CPB retained a certain level of load-bearing ***,the failure of the CPB was dominated by tensile *** the addition of WTSF,a gradual increase in the proportion of tensile cracks was observed upon loading the modified CPB sample to the pore compaction *** three-dimensional localization of AE events showed that the WTSF-modified CPB underwent progressive damage during the loading,and the samples still showed good integrity after ***,the response relationship between energy evolution and damage development of WTSF-modified CPB during uniaxial compression was analyzed,and the damage constitutive model of CPB samples with different WTSF contents was *** study provides a theoretical basis for the enhancement of CPB modified by adding WTSF,serving as a valuable reference for the design of CPB constructional backfill.

关键词： Constructional backfill Cemented paste backfill Waste tire steel fiber Acoustic emission Damage characteristics

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Surface crack evolution patterns in freeze-thaw damage of fissured rock bodies

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Journal of Mountain Science 2024年第9期21卷 3094-3107页

作者： KANG Zhiqiang WANG Zhilei SHAO Luhang FENG Jiangjiang YAO Xulong college of mining engineering North China University of Science and TechnologyTangshan 063200China Green Intelligent mining Technology Innovation Center of Hebei Province North China University of Science and TechnologyTangshan 063210China Luannan Macheng mining Co. Ltd.Shougang Group Co.LtdLuannan CountyTangshan 063500China

To explore the effects of freeze‒thaw cycles on the mechanical properties and crack evolution of fissured sandstone,biaxial compression experiments were carried out on sandstone subjected to freeze‒thaw cycles to characterize the changes in the physical and mechanical properties of fissured sandstone caused by freeze‒thaw *** crack evolution and crack change process on the surface of the fissured sandstone were recorded and analysed in detail via digital image technology(DIC).Numerical simulation was used to reveal the expansion process and damage mode of fine-scale cracks under the action of freeze‒thaw cycles,and the simulation results were compared and analysed with the experimental data to verify the reliability of the numerical *** results show that the mass loss,porosity,peak stress and elastic modulus all increase with increasing number of freeze‒thaw *** an increase in the number of freeze‒thaw cycles,a substantial change in displacement occurs around the prefabricated cracks,and a stress concentration appears at the crack *** new cracks continue to sprout at the tips of the prefabricated cracks until the microcracks gradually penetrate into the main cracks,the displacement cloud becomes obviously discontinuous,and the contours of the displacement field in the crack fracture damage area simply intersect with the prefabricated cracks to form an obvious *** damage patterns of the fractured sandstone after freeze‒thaw cycles clearly differ,forming a symmetrical"L"-shaped damage pattern at zero freeze‒thaw cycles,a symmetrical"V"-shaped damage pattern at 10 freeze‒thaw cycles,and a"V"-shaped damage pattern at 20 freeze‒thaw *** 20 freeze‒thaw cycles,a"V"-shaped destruction pattern and"L"-shaped destruction pattern are formed;after 30 freeze‒thaw cycles,an"N"-shaped destruction pattern is *** shows that the failure mode of fractured sandstone gradually becomes more complicated with an increasing number of freeze‒t

关键词： Freeze‒thaw cycles Fissured sandstone Particle flow software Rock mechanics Crack extension pattern DIC technique

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Extraction of fractures in shale CT images using improved U-Net

Energy Geoscience

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Energy Geoscience 2024年第2期5卷 240-248页

作者： Xiang Wu Fei Wang Xiaoqiu Zhang Bohua Han Qianru Liu Yonghao Zhang college of Geology engineering and geomatics Chang'an UniversityXi'anShaanxi710054China Qinghai Oilfield Exploration and Development Research Institute DunhuangGansu736202China China Petroleum Logging Co.Ltd. Xi'anShaanxi710077China

Accurate extraction of pores and fractures is a prerequisite for constructing digital rocks for physical property simulation and microstructural response ***,fractures in CT images are similar in grayscale to the rock matrix,and traditional algorithms have difficulty to achieve accurate segmentation *** this study,a dataset containing multiscale fracture information was constructed,and a U-Net semantic segmentation model with a scSE attention mechanism was used to classify shale CT images at the pixel level and compare the results with traditional *** results showed that the CLAHE algorithm effectively removed noise and enhanced the fracture information in the dark parts,which is beneficial for further fracture *** Canny edge detection algorithm had significant false positives and failed to recognize the internal information of the *** Otsu algorithm only extracted fractures with a significant difference from the background and was not sensitive enough for fine *** MEF algorithm enhanced the edge information of the fractures and was also sensitive to fine fractures,but it overestimated the aperture of the *** U-Net was able to identify almost all fractures with good continuity,with an MIou and Recall of 0.80 and 0.82,*** the image resolution increases,more fine fracture information can be extracted.

关键词： CT slices Fracture segmentation Shale U-Net Deep learning

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Cyclic shear behavior of en-echelon joints under constant normal stiffness conditions

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Journal of Rock Mechanics and Geotechnical engineering 2024年第9期16卷 3419-3436页

作者： Bin Wang Yujing Jiang Qiangyong Zhang Hongbin Chen Richeng Liu Yuanchao Zhang Graduate School of engineering Nagasaki UniversityNagasaki852-8521Japan Research Center of Geotechnical and Structural engineering Shandong UniversityJi’nan250061China State Key Laboratory for Geomechanics and Deep Underground engineering China University of Mining and TechnologyXuzhou221116China college of Civil engineering Fuzhou UniversityFuzhou350108China

To reveal the mechanism of shear failure of en-echelon joints under cyclic loading,such as during earthquakes,we conducted a series of cyclic shear tests of en-echelon joints under constant normal stiffness(CNS)*** analyzed the evolution of shear stress,normal stress,stress path,dilatancy characteristics,and friction coefficient and revealed the failure mechanisms of en-echelon joints at different *** results show that the cyclic shear behavior of the en-echelon joints is closely related to the joint angle,with the shear strength at a positive angle exceeding that at a negative angle during shear *** the number of cycles increases,the shear strength decreases rapidly,and the difference between the varying angles gradually *** occurs in the early shear cycles(1 and 2),while contraction is the main feature in later cycles(310).The friction coefficient decreases with the number of cycles and exhibits a more significant sensitivity to joint angles than shear *** joint angle determines the asperities on the rupture surfaces and the block size,and thus determines the subsequent shear failure mode(block crushing and asperity degradation).At positive angles,block size is more greater and asperities on the rupture surface are smaller than at nonpositive ***,the cyclic shear behavior is controlled by block crushing at positive angles and asperity degradation at negative angles.

关键词： En-echelon joint Cyclic shear tests Shear stress Normal displacement Constant normal stiffness(CNS)

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Failure evaluation and control factor analysis of slope block instability along traffic corridor in Southeastern Tibet

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Journal of Mountain Science 2024年第6期21卷 1830-1848页

作者： LIU Changqing BAO Han LAN Hengxing YAN Changgen LI Changbo LIU Shijie School of Highway Chang'an UniversityXi'an 710064China State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China college of Geological engineering and geomatics Chang'an UniversityXi'an 710054China

The instability of slope blocks occurred frequently along traffic corridor in Southeastern Tibet(TCST),which was primarily controlled by the rock mass structures.A rapid method evaluating the control effects of rock mass structures was proposed through field statistics of the slopes and rock mass structures along TCST,which combined the stereographic projection method,modified M-JCS model,and limit equilibrium *** instabilities of slope blocks along TCST were then evaluated rapidly,and the different control factors of instability were *** showed that the probabilities of toppling(5.31%),planar(16.15%),and wedge(35.37%)failure of slope blocks along TCST increased *** instability modes were respectively controlled by the anti-dip joint,the joint parallel to slope surface with a dip angle smaller than the slope angle(singlejoint),and two groups of joints inclined out of the slope(double-joints).Regarding the control effects on slope block instability,the stabilization ability of doublejoints(72.7%),anti-dip joint(67.4%),and single-joint(57.6%)decreased sequentially,resulting in different probabilities of slope block ***,nearby regional faults significantly influenced the joints,leading to spatial heterogeneity and segmental clustering in the stabilization ability provided by joints to the slope ***,the stability of slope blocks gradually weakened as they approached the fault *** paper can provide guidance and assistance for investigating the development characteristics of rock mass structures and the stability of slope blocks.

关键词： Slope engineering Block instability Rapid evaluation method Rock mass structure Control factor

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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 *** 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)*** 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 *** 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 *** processes include penetration,push-in with or without rod,pull-back with or without rod,rod-tightening and *** drilling data are further reconstructed to plot the curve of drill-bit depth versus the net drilling time along each of the six *** curve is found to contain multiple linear segments with a constant penetration rate,which implies a zone of homogenous geomaterial with different weathering *** effect from fluctuation of the applied pressures is evaluated *** 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

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Effect of long reaction distance on gas composition from organic-rich shale pyrolysis under high-temperature steam environment

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International Journal of Coal Science & Technology 2024年第3期11卷 102-119页

作者： Lei Wang Rui Zhang Guoying Wang Jing Zhao Dong Yang Zhiqin Kang Yangsheng Zhao Key Laboratory of In-Situ Property Improving mining of Ministry of Education Taiyuan University of TechnologyTaiyuan030024China The In-Situ Steam Injection Branch of State Center for Research and Development of Organic-Rich Shale Exploitation Taiyuan University of TechnologyTaiyuan030024China college of mining engineering Taiyuan University of TechnologyTaiyuan030024China School of Energy Science and engineering Henan Polytechnic UniversityJiaozuo454002China

When high-temperature steam is used as a medium to pyrolyze organic-rich shale,water steam not only acts as heat transfer but also participates in the chemical reaction of organic matter pyrolysis,thus affecting the generation law and release characteristics of gas *** this study,based on a long-distance reaction system of organic-rich shale pyrolysis via steam injection,the effects of steam temperature and reaction distance on gas product composition are analyzed in depth and compared with other pyrolysis *** advantages of organic-rich shale pyrolysis via steam injection are then *** volume concentration of hydrogen in the gas product obtained via the steam injection pyrolysis of organic-rich shale is the highest,which is more than 60%.The hydrogen content increases as the reaction distance is extended;however,the rate of increase changes *** the reaction distance from 800 to 4000 mm increases the hydrogen content from 34.91%to 69.68%and from 63.13%to 78.61%when the steam temperature is 500℃ and 555℃,***,the higher the heat injection temperature,the smaller the reaction distance required to form a high concentration hydrogen pyrolysis environment(hydrogen concentration>60%).When the steam pyrolysis temperature is increased from 500℃ to 555℃,the reaction distance required to form a high concentration of hydrogen is reduced from 3800 to 800 *** with the direct retorting process,the volume concentration of hydrogen obtained from high-temperature steam pyrolysis of organic-rich shale is 8.82 and 10.72 times that of the commonly used Fushun and Kivite furnaces,*** pyrolysis of organic-rich shale via steam injection is a pyrolysis process in a hydrogen-rich environment.

关键词： Steam temperature Pyrolysis gas Hydrogen-rich Reaction distance Direct retorting

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Application of integrated geophysical techniques in geothermal exploration in Binhai County, Jiangsu Province

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Deep Underground Science and engineering 2024年第3期3卷 338-348页

作者： Juncheng Wang Shiyin Gao Jianguo Wang Lin Li Xiaoyan Gong Jinbao Su college of Oceanography Hohai UniversityNanjingChina School of Earth Sciences and engineering Hohai UniversityNanjingChina Geological Exploration Technology Institute of Jiangsu Province NanjingChina Jiangsu engineering Research Center for Aeronautical Earth Exploration and Intelligent Sensing NanjingChina School of Mechanics and Civil engineering China University of Mining and TechnologyXuzhouChina State Key Laboratory for Geomechanics and Deep Underground engineering China University of Mining and TechnologyXuzhouChina

Integrated geophysical technology is a necessary and effective means for geothermal ***,integration of geophysical technology for large‐scale surveys with those for geothermal reservoir localization is still in *** study used the controlled source audio‐frequency magnetotelluric method technology for large‐scale exploration to obtain underground electrical structure information and micromotion detection technology to obtain underground wave velocity structure *** combination of two detection technologies was used for local identification of geothermal ***,auxiliary correction and inversion constraint were implemented through the audio magnetotelluric sounding technology for maximum authenticity restoration of the near‐and transition‐field *** these technology improvements,a geothermal geological model was established for the Binhai County of Jiangsu Province in China and potential geothermal well locations were *** this basis,a geothermal well was drilled nearly 3000m deep,with a daily water volume of over 2000m3/day and a geothermal water temperature of 51°C at the well *** is found that predictions using the above integrated geophysical exploration technology are in good agreement with the well geological formation *** integrated geophysical technology can be effectively applied for geothermal exploration with high precision and reliability.

关键词： controlled source audio frequency magnetotelluric method(CSAMT) geothermal exploration integrated geophysical technology micromotion detection technology

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