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Frictional characteristics of rough granite fractures subjected to various normal loading/unloading rates and shear velocities 认领 引用
1
作者 ZHANG Chuan-jiu DUAN Hong-fei +5 位作者 LI Xing-ling BAI Zhen-chao LI Peng WANG Wei LI Xuan-liang DANG Wen-gang 《Journal of Central South University》 SCIE EI CAS CSCD 2026年第5期2243-2266,共24页
The shear behavior of rock joints under dynamic disturbances is still not well understood,especially when subjected to irregular stress waveforms,which are common in real-world scenarios.In this study,a series of cycl... The shear behavior of rock joints under dynamic disturbances is still not well understood,especially when subjected to irregular stress waveforms,which are common in real-world scenarios.In this study,a series of cyclic normal loading/unloading direct shear tests was conducted on rough granite fractures using a laboratory direct shear apparatus.The effects of different normal loading rates,unloading rates,and shear velocities on shear stress,apparent friction coefficient,normal displacement,and shear work were systematically analyzed.The experimental results indicated that as the normal loading and unloading rates increase and the shear velocity decreases,the peak shear stress and shear work decrease.Compared with quasi-static shear strength,dynamic normal stress disturbance may strengthen the dynamic shear strength or weaken it,and the strengthening/weakening degree is controlled by the normal loading/unloading rates and shear velocity.Furthermore,three distinct shear stress variation patterns(linear decay,nonlinear decay,and peak delay)are observed.These findings provide a theoretical basis for evaluating the stability of jointed rock masses under complex dynamic disturbances such as earthquakes,tidal effects,traffic loads,and blasting activities. 展开更多
关键词 rough granite fracture normal loading/unloading rates shear velocity frictional strengthening frictional weakening
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Experimental study on failure precursory characteristics and moisture content effect of pre-cracked rocks under graded cyclic loading and unloading 认领 引用 被引量：4
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作者 Wei Zhang Dongxiao Zhang +1 位作者 Weiyao Guo Baoliang Zhang 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2025年第2期249-264,共16页
It is important to analyze the damage evolution process of surrounding rock under different water content for the stability of engineering rock mass.Based on digital speckle correlation(DSCM),acoustic emission(AE)and ... It is important to analyze the damage evolution process of surrounding rock under different water content for the stability of engineering rock mass.Based on digital speckle correlation(DSCM),acoustic emission(AE)and electromagnetic radiation(EMR),uniaxial hierarchical cyclic loading and unloading tests were carried out on sandstones with different fracture numbers under dry,natural and saturated water content,to explore the fracture propagation,failure precursor characteristics and damage response mechanism under the influence of water content effect.The results show that with the increase of water content,the peak stress and crack initiation stress decrease gradually,and the decreases are 15.28%-21.11%and 17.64%-23.04%,respectively.The peak strain and crack initiation strain increase gradually,and the increases are 19.85%-44.53%and 19.15%-41.94%,respectively.The precracked rock with different water content is mainly characterized by tensile failure at different loading stages.However,with the increase of water content,the proportion of shear cracks gradually increases,while acoustic emission events gradually decrease,the dissipative energy and energy storage limits of the rock under peak load gradually decrease,and the charge signal increases significantly,which is because the lubrication effect of water reduces the friction coefficient between crack surfaces. 展开更多
关键词 Damage mechanisms Pre-cracked rocks Crack propagation Water-rock interaction Graded cyclic loading and unloading
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Microstructure evolution in anisotropic tight sandstones under hydrostatic loading and unloading processes 认领 引用 被引量：1
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作者 Xiaying Li Haimeng Shen Qi Li 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2025年第3期1528-1538,共11页
Preexisting cracks inside tight sandstones are one of the most important properties for controlling the mechanical and seepage behaviors.During the cyclic loading process,the rock generally exhibits obvious memorabili... Preexisting cracks inside tight sandstones are one of the most important properties for controlling the mechanical and seepage behaviors.During the cyclic loading process,the rock generally exhibits obvious memorability and irreversible plastic deformation,even in the linear elastic stage.The assessment of the evolution of preexisting cracks under hydrostatic pressure loading and unloading processes is helpful in understanding the mechanism of plastic deformation.In this study,ultrasonic measurements were conducted on two tight sandstone specimens with different bedding orientations subjected to hydrostatic loading and unloading processes.The P-wave velocity was characterized by a similar response with the volumetric strain to the hydrostatic pressure and showed different strain sensitivities at different loading and unloading stages.A numerical model based on the discrete element method(DEM)was proposed to quantitatively clarify the evolution of the crack distribution under different hydrostatic pressures.The numerical model was verified by comparing the evolution of the measured P-wave velocities on two anisotropic specimens.The irreversible plastic deformation that occurred during the hydrostatic unloading stage was mainly due to the permanent closure of plastic-controlled cracks.The closure and reopening of cracks with a small aspect ratio account for the major microstructure evolution during the hydrostatic loading and unloading processes.Such evolution of microcracks is highly dependent on the stress path.The anisotropy of the crack distribution plays an important role in the magnitude and strain sensitivity of the P-wave velocity under stress conditions.The study can provide insight into the microstructure evolution during cyclic loading and unloading processes. 展开更多
关键词 Plastic deformation P-wave velocity Discrete element method(DEM) Cyclic loading and unloading Crack evolution
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Mechanical properties and dilatancy angle model of jointed hard rock under true triaxial cyclic loading and unloading 认领 引用
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作者 Hong Xu Gang Wang +3 位作者 Quan Jiang Shili Qiu Guangliang Feng Xiang Huang 《International Journal of Coal Science & Technology》 SCIE EI CAS CSCD 2025年第6期95-108,共14页
Joints play a crucial role in the stability of surrounding rock in deep underground engineering.Studying the mechanical properties and evolution laws of rocks with different joint characteristics under true triaxial s... Joints play a crucial role in the stability of surrounding rock in deep underground engineering.Studying the mechanical properties and evolution laws of rocks with different joint characteristics under true triaxial stress is highly significant.This paper presents the results of a series of true triaxial cyclic loading and unloading experiments conducted on natural stiff-jointed and artificially jointed granite,where the correlation between fracture characteristics and joint inclination was investigated.It was observed that the peak strength,plastic volumetric strain,and failure mode of the jointed granite varied considerably with joint inclination.This underscores the significant influence of joint inclination on the mechanical behavior of deep granite.Building upon a comprehensive understanding of the strength characteristics and deformation evolution in jointed granite with varying inclinations,a new dilation angle model was developed,incorporating the coupling effects of plastic volumetric strain and joint inclination.A strong agreement was found between our theoretical predictions and test data,suggesting that the proposed dilation angle model can effectively describe the dilatancy characteristics of granite with joints.This study is anticipated to offer a theoretical basis for excavation and support design,as well as stability analysis of deep jointed rock masses. 展开更多
关键词 True triaxial cyclic loading and unloading Joints Inclination Plastic volumetric strain Dilation angle
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Mechanical behavior of sandstone during post-peak cyclic loading and unloading under hydromechanical coupling 认领 引用 被引量：11
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作者 Yanlin Zhao Jinhai Liu +4 位作者 Chunshun Zhang Houquan Zhang Jian Liao Sitao Zhu Lianyang Zhang 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2023年第8期927-947,共21页
This paper investigates mechanical behaviours of sandstone during post-peak cyclic loading and unloading subjected to hydromechanical coupling effect, confirming the peak and residual strengths reduction laws of sands... This paper investigates mechanical behaviours of sandstone during post-peak cyclic loading and unloading subjected to hydromechanical coupling effect, confirming the peak and residual strengths reduction laws of sandstone with water pressure, and revealing the influence of water pressure on the upper limit stress and deformation characteristics of sandstone during post-peak cyclic loading and unloading.Regarding the rock strength, the experimental study confirms that the peak strength σp and residual strength σr decrease as water pressure P increases. Especially, the normalized strength parameters σp/σpk and σr/σre was negatively and linearly correlated with the P/σ3. Moreover, the Hoek-Brown strength criterion can be applied to describe the relationship between effective peak strength and effective confining stress. During post-peak cyclic loading and unloading, both the upper limit stress σp(i) and crack damage threshold stress σcd(i) of each cycle tend to decrease with the increasing cycle number. A hysteresis loop exists among the loading and unloading stress–strain curves, indicating the unloading deformation modulus Eunload is larger than the loading deformation modulus Eload. Based on experimental results,a post-peak strength prediction model related to water pressure and plastic shear strain is established. 展开更多
关键词 Post-peak stage Cyclic loading and unloading Hydromechanical coupling Sandstone Water pressure
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Morphological evolution and flow conduction characteristics of fracture channels in fractured sandstone under cyclic loading and unloading 认领 引用 被引量：16
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作者 Quanle Zou Zihan Chen +4 位作者 Jinfei Zhan Chunmei Chen Shikang Gao Fanjie Kong Xiaofeng Xia 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2023年第12期1527-1540,共14页
In coal mining,rock strata are fractured under cyclic loading and unloading to form fracture channels.Fracture channels are the main flow narrows for gas.Therefore,expounding the flow conductivity of fracture channels... In coal mining,rock strata are fractured under cyclic loading and unloading to form fracture channels.Fracture channels are the main flow narrows for gas.Therefore,expounding the flow conductivity of fracture channels in rocks on fluids is significant for gas flow in rock strata.In this regard,graded incremental cyclic loading and unloading experiments were conducted on sandstones with different initial stress levels.Then,the three-dimensional models for fracture channels in sandstones were established.Finally,the fracture channel percentages were used to reflect the flow conductivity of fracture channels.The study revealed how the particle size distribution of fractured sandstone affects the formation and expansion of fracture channels.It was found that a smaller proportion of large blocks and a higher proportion of small blocks after sandstone fails contribute more to the formation of fracture channels.The proportion of fracture channels in fractured rock can indicate the flow conductivity of those channels.When the proportion of fracture channels varies gently,fluids flow evenly through those channels.However,if the proportion of fracture channels varies significantly,it can greatly affect the flow rate of fluids.The research results contribute to revealing the morphological evolution and flow conductivity of fracture channels in sandstone and then provide a theoretical basis for clarifying the gas flow pattern in the rock strata of coal mines. 展开更多
关键词 CT imaging Flow conductivity Three-dimensional reconstruction Proportion of fracture channels Cyclic loading and unloading
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Experimental investigation on damage evolution behaviour of a granitic rock under loading and unloading 认领 引用 被引量：11
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作者 戴兵 赵国彦 +1 位作者 H.KONIETZKY P.L.P.WASANTHA 《Journal of Central South University》 SCIE EI CAS CSCD 2018年第5期1213-1225,共13页
In-situ rock failures can result from stress changes due to pure loading and/or unloading. Understanding of the damage evolution behavior in brittle rocks during loading and unloading is imperative for the designs of ... In-situ rock failures can result from stress changes due to pure loading and/or unloading. Understanding of the damage evolution behavior in brittle rocks during loading and unloading is imperative for the designs of rock structures. In this paper, we investigate the damage evolution characteristics of a granitic rock during loading and unloading after a series of triaxial experiments performed at different confining pressures. The axial stress-axial strain variations of the tested specimens revealed that the specimens undergoing unloading fail with a lower axial strain compared to the specimens failed purely by loading. Higher confining pressures were observed to exacerbate the difference. Volumetric strain versus axial strain curves indicated that the curves reverse the trend with the beginning of major damage of specimens. We suggest here a new form of equation to describe the secant modulus variation of brittle rocks against the axial stress for the unloading process. Failure mechanisms of tested specimens showed two distinct patterns, namely, specimens under pure loading failed with a single distinct shear fracture while for the unloading case specimens displayed multiple intersecting fractures. In addition, analysis of the evolution of dissipation and elastic energy during deformation of the specimens under loading and unloading conditions showed differentiable characteristics. Moreover, we evaluated the variations of two damage indices defined based on the energy dissipation and secant modulus evolution during deformation and observed that both of them satisfactorily distinguish key stages of damage evolution. 展开更多
关键词 damage evolution loading and unloading granitic rock triaxial testing
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Calculation of foundation pit deformation caused by deep excavation considering influence of loading and unloading 认领 引用 被引量：16
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作者 黄明 刘新荣 +1 位作者 张乃烊 沈启炜 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第9期2164-2171,共8页
A new analytical solution for ground surface settlement induced by deep excavation is proposed based on the elastic half space Melan’s solution,and the analytical model is related to the physical and mechanical prope... A new analytical solution for ground surface settlement induced by deep excavation is proposed based on the elastic half space Melan’s solution,and the analytical model is related to the physical and mechanical properties of soil with the loading and unloading action during excavation process.The change law of earth pressure of the normal consolidation soil after the foundation pit excavation was analyzed,and elastic displacement calculation methods of analytic solution were further established given the influence of excavation and unloading.According to the change of stress state in the excavation process of foundation pit,the planar mechanical analysis model of the foundation excavation problem was established.By combining this model with the physical equations and geometric equations of plane strain problem with consideration of the loading and unloading modulus of soil,constitutive equation of the plane strain problem was also established.The loading and unloading modulus formula was obtained by using the parameter calculation method in Duncan-Chang curve model.The constitutive equation obtained from the model was used to calculate the soil stress state of each point to determine its loading and unloading modulus.Finally,the foundation pit displacement change after excavation was calculated,and thus the soil pressure distribution after retaining structure deformation.The theoretical results calculated by making corresponding programs were applied to engineering practice.By comparing the conventional calculation results with monitoring results,the practicability and feasibility of the calculation model were verified,which should provide a theoretical basis for similar projects. 展开更多
关键词 foundation pit Melan＇s solution loading and unloading stress state Duncan-Chang curve model
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Mechanical and hydraulic properties of fault rocks under multi‑stage cyclic loading and unloading 认领 引用 被引量：3
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作者 Wentao Hou Dan Ma +3 位作者 Qiang Li Jixiong Zhang Yong Liu Chenyao Zhou 《International Journal of Coal Science & Technology》 EI CAS CSCD 2023年第4期151-170,共20页
The rock mass in fault zones is frequently subjected to cyclic loading and unloading during deep resource exploitation and tunnel excavation.Research on the mechanical and hydraulic characteristics of fault rock durin... The rock mass in fault zones is frequently subjected to cyclic loading and unloading during deep resource exploitation and tunnel excavation.Research on the mechanical and hydraulic characteristics of fault rock during the cyclic loading and unloading is of great signifcance for revealing the formation mechanism of water-conducting pathways in fault and preventing water inrush disasters.In this study,the mechanical and seepage tests of fault rock under the multi-stage cyclic loading and unloading of axial compression were carried out by using the fuid–solid coupling triaxial experimental device.The hysteresis loop of the stress–strain curve,peak strain rate,secant Young's modulus,and permeability of fault rock were obtained,and the evolution law of the dissipated energy of fault rock with the cyclic number of load and unloading was discussed.The experimental results show that with an increase in the cyclic number of loading and unloading,several changes occur.The hysteresis loop of the stress–strain curve of the fault rock shifts towards higher levels of strain.Additionally,both the peak strain rate and the secant Young's modulus of the fault rock increase,resulting in an increase in the secant Young's modulus of the fault rock mass.However,the growth rate of the secant Young's modulus gradually slows down with the increase of cyclic number of loading and unloading.The permeability evolution of fault rock under the multi-stage cyclic loading and unloading of axial compression can be divided into three stages:steady increase stage,cyclic decrease stage,and rapid increase stage.Besides,the calculation model of dissipated energy of fault rock considering the efective stress was established.The calculation results show that the relationship between the dissipated energy of fault rock and the cyclic number of loading and unloading conforms to an exponential function. 展开更多
关键词 Multi-stage cyclic loading and unloading Fault rocks Mechanical properties Hydraulic properties Energy dissipation
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Mechanical Properties of Deep-buried Marble Material Under Loading and Unloading Tests 认领 引用 被引量：3
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作者 李新平 ZHAO Hang +1 位作者 WANG Bin XIAO Taoli 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2013年第3期514-520,共7页
The mechanical properties are essentially different when rock material is subjected to loading or unloading conditions. In this study, loading and unloading tests with various confining pressures are conducted to inve... The mechanical properties are essentially different when rock material is subjected to loading or unloading conditions. In this study, loading and unloading tests with various confining pressures are conducted to investigate the mechanical properties of marble material samples taken from the deep diversion tunnels of Jinping II Hydropower Station. The stress-strain relationship, failure characteristics and strength criterion are compared and analyzed based on the experiment results. The results show： in the loading and unloading test, peak strength, lateral strain, axial strain and plastic deformation increase significantly as the confining pressure increases. Lateral strain increased significantly and obvious lateral dilatancy can be observed to the change of confining pressure; The fracture mode is mainly the single shear fracture for the triaxial compression test and post-peak test, angle between the failure surface and the ends of the rock material becomes smaller as the confining pressure increases. Hock-Brown strength criterion reflects the strength characteristics of marble material under two different unloading conditions, and has some supplementary effects to the rock material of mechanical field. 展开更多
关键词 deep-buried material loading and unloading tests mechanical properties strength criterion shear fracture
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The deformation and permeability of Yanji mudstone under cyclic loading and unloading 认领 引用 被引量：2
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作者 ZENG Zhi-xiong KONG Ling-wei WANG Jun-tao 《Journal of Mountain Science》 SCIE CSCD 2019年第12期2907-2919,共13页
During the constructions of motorways and high-speed railway lines in the Yanji Basin,large amounts of excess mudstones due to the enormous tunnel excavations and slope cuts would be deposited as landfills.Assessing t... During the constructions of motorways and high-speed railway lines in the Yanji Basin,large amounts of excess mudstones due to the enormous tunnel excavations and slope cuts would be deposited as landfills.Assessing the deformation and permeability of Yanji mudstone became important for the design,construction and operation of the landfills.This paper presents an experimental study on the deformation and permeability of Yanji mudstone by carrying out a series of oedometer tests with loading/unloading cycles.The results show that the sample with a lower initial water content exhibited greater swelling deformation after inundation,a lower yield stress,greater deformation and a higher hydraulic conductivity during the loading/unloading cycles.As the number of loading/unloading cycles increased,the yield stress and accumulated plastic deformation increased,while the compression index,rebound index and hydraulic conductivity decreased.The samples became stiffer and their hydromechanical behaviour tended to be stable after three cycles.The compression curves could be divided into pre-yield and post-yield zones.The post-yield zones of compression curves and the rebound curves could be normalized into a unique line,and the pre-yield zones of the compression curves could be described as lines.Basic equations were developed to predict mudstone deformation under cyclic loading and unloading.Additionally,an empirical relationship between the hydraulic conductivity and void ratio was also proposed.The ability of the proposed methods was verified by the overall good agreement between the experimental results and predicted values. 展开更多
关键词 Mudstone Swelling Cyclic loading and unloading Deformation Permeability
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Damage evolution in sandstone under uniaxial cyclic loading and varying water contents:Theoretical and experimental investigation 认领 引用 被引量：1
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作者 ZHANG Sheng BAI Wei +3 位作者 XU Ding-ping ZHENG Hong JIANG Quan LI Zhi-wei 《Journal of Central South University》 SCIE EI CAS CSCD 2025年第8期3095-3110,共16页
During underground excavation,the surrounding rock mass is subjected to complex cyclic stress,significantly impacting its long-term stability,especially under varying water content conditions where this effect is ampl... During underground excavation,the surrounding rock mass is subjected to complex cyclic stress,significantly impacting its long-term stability,especially under varying water content conditions where this effect is amplified.However,research on the mechanical response mechanisms of surrounding rock mass under such conditions remains inadequate.This study utilized acoustic emission(AE)and resistivity testing to monitor rock fracture changes,revealing the rock’s damage state and characterizing the damage evolution process during uniaxial cyclic loading and unloading.First,a damage variable equation was established based on AE and resistivity parameters,leading to the derivation of a corresponding damage constitutive equation.Uniaxial cyclic loading and unloading tests were then conducted on sandstone samples with varying water contents,continuously monitoring AE signals and resistivity,along with computed tomography scans before and after failure.The predictions from the damage constitutive equation were compared with experimental results.This comparison shows that the proposed damage variable equation effectively characterizes the damage evolution of sandstone during loading and unloading,and that the constitutive equation closely fits the experimental data.This study provides a theoretical basis for monitoring and assessing the responses of surrounding rock mass during underground excavation. 展开更多
关键词 sandstone acoustic emission rock resistivity uniaxial cyclic loading and unloading rock cracks damage constitutive equation
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Damage evolution and failure behavior of coal-rock combination subjected to different cyclic loading paths and loading rates: Insights from energy-driven effects 认领 引用
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作者 WANG Kai ZUO Xiao-huan +4 位作者 DU Feng SUN Jia-zhi JU Yang SHU Long-yong CAI Yong-bo 《Journal of Central South University》 SCIE EI CAS CSCD 2025年第9期3447-3469,共23页
In this study,a uniaxial cyclic compression test is conducted on coal-rock composite structures under two cyclic loads using MTSE45.104 testing apparatus to investigate the macro-mesoscopic deformation,damage behavior... In this study,a uniaxial cyclic compression test is conducted on coal-rock composite structures under two cyclic loads using MTSE45.104 testing apparatus to investigate the macro-mesoscopic deformation,damage behavior,and energy evolution characteristics of these structures under different cyclic stress disturbances.Three loading and unloading rates(LURs)are tested to examine the damage behaviors and energy-driven characteristics of the composites.The findings reveal that the energy-driven behavior,mechanical properties,and macro-micro degradation characteristics of the composites are significantly influenced by the loading rate.Under the gradual cyclic loading and unloading(CLU)path with a constant lower limit(path I)and the CLU path with variable upper and lower boundaries(path II),an increase in LURs from 0.05 to 0.15 mm/min reduces the average loading time by 32.39%and 48.60%,respectively.Consequently,the total number of cracks in the samples increases by 1.66-fold for path I and 1.41-fold for path II.As LURs further increase,the energy storage limit of samples expands,leading to a higher proportion of transmatrix and shear cracks.Under both cyclic loading conditions,a broader cyclic stress range promotes energy dissipation and the formation of internal fractures.Notably,at higher loading rates,cracks tend to propagate along primary weak surfaces,leading to an increased incidence of intermatrix fractures.This behavior indicates a microscopic feature of the failure mechanisms in composite structures.These results provide a theoretical basis for elucidating the damage and failure characteristics of coal-rock composite structures under cyclic stress disturbances. 展开更多
关键词 coal-rock composite samples cyclic loading loading and unloading rates RA-AF correlation macro-micro damage features failure behavior
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The design of automatic loading-and-unloading material manipulator for telescopic punch 认领 引用 被引量：3
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作者 Luo Lei Wei Zhenchun +2 位作者 Jin Aimin Wang Jinbo Zhang Li 《Computer Aided Drafting,Design and Manufacturing》 2016年第2期58-62,共5页
To reduce the amount of labor in the sheet metal stamping industry, improve the processing efficiency and safety factor and realize the automatic production of stamping, this paper designs a new type of overall plan a... To reduce the amount of labor in the sheet metal stamping industry, improve the processing efficiency and safety factor and realize the automatic production of stamping, this paper designs a new type of overall plan about automatic loading and unloading material manipulator for telescopic punch which can realize the telescopic movements with two degrees. The mechanical structure of the manipulator includes a lifting device and a telescopic device. Using PLC control program, the control system can automatically achieve continuous beat actions of drawing and stacking for the processing raw materials. According to the mechanical structure, the paper analyzes the working principle and control strategy of each component in the loading-and-unloading material manipulator systems. 展开更多
关键词 automatic loading and unloading system manipulator PLC control
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A STUDY OF THE POSTBUCKLING PATH OF CYLINDRICALLY CURVED PANELS OF LAMINATED COMPOSITE MATERIALS DURING LOADING AND UNLOADING 认领 引用 被引量：1
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作者 董万林 黄小清 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1990年第7期651-657,共7页
In this paper, Dynamic Relaxation Method is applied to study the postbuckling path of cylindrically curved panels of laminated composite materials during loading and unloading. The phenomenon that loading paths do not... In this paper, Dynamic Relaxation Method is applied to study the postbuckling path of cylindrically curved panels of laminated composite materials during loading and unloading. The phenomenon that loading paths do not coincide with unloading paths has been found. Numerical results are given for cylindrically curved cross-ply panels subjected to uniform uniaxial compression under two types of boundary conditions. The influence of the number of layers, the panels curvature and the initial imperfection on the postbuckling paths is discussed. 展开更多
关键词 A STUDY OF THE POSTBUCKLING PATH OF CYLINDRICALLY CURVED PANELS OF LAMINATED COMPOSITE MATERIALS DURING LOADING AND UNLOADING
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Analysis of Hydraulic Lifting Device for Wind Power Tower Loading and Unloading Vehicle 认领 引用
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作者 HUANG Longheng LEI Yi YANG Xueliang 《外文科技期刊数据库（文摘版）工程技术》 2021年第12期1109-1112,共4页
In the construction of wind power tower, the loading and unloading operation of tower is basically involved. However, due to the large size of wind power tower and its great characteristics in weight, it is necessary ... In the construction of wind power tower, the loading and unloading operation of tower is basically involved. However, due to the large size of wind power tower and its great characteristics in weight, it is necessary to use two gantry cranes to handle the tower crane at the same time, so as to effectively meet the transportation and handling of loading and unloading vehicles. However, in the actual construction, it is often affected by the heavy operation of the equipment. Therefore, based on this situation, this paper studies the hydraulic lifting device for wind power tower loading and unloading vehicle, in order to ensure that the device can play its due role in operation. 展开更多
关键词 wind power tower loading and unloading vehicles hydraulic lifting device crane lifting rod
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Towards early rockburst susceptibility assessment:A simple approach combining acoustic emission and uniaxial compression tests 认领 引用
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作者 WU Chen ZHOU Ming-liang +4 位作者 GONG Feng-qiang HE Zhi-chao PENG Zi-mu ZHANG Le ZHU Shuai-da 《Journal of Central South University》 SCIE EI CAS CSCD 2026年第5期2099-2118,共20页
The discrimination of rockburst proneness is crucial for ensuring the safe construction of deep underground rock engineering.This study aims to propose a novel criterion for predicting rockburst proneness based on roc... The discrimination of rockburst proneness is crucial for ensuring the safe construction of deep underground rock engineering.This study aims to propose a novel criterion for predicting rockburst proneness based on rock crack damage strength(σCD)and the load/unload response ratio(LURR)theory.Uniaxial compression(UC)tests and uniaxial compression graded load-unload(UCGL)tests were conducted on 13 distinct rocks.The consistency betweenσCDpoints and LURR start-rise points was analyzed,and an improved acoustic emission(AE)Kneedle algorithm was developed to quantitatively calculateσCDbased on AE data.A novel lag time ratio index(TCDAE)was defined as the ratio of the loading time interval betweenσCDand peak strength.The fitting degree betweenσCDpoints and LURR start-rise points reached 0.983,demonstrating strong consistency.The improved AE method for determiningσCDshowed a correlation of 0.993 with the classical crack volume strain method,confirming its effectiveness.The proposed TCDAE-based criterion significantly reduced discrimination time by at least 50%while maintaining high accuracy.A novel rockburst proneness criterion based on TCDAE was established,offering improved efficiency and reliability compared to existing methods. 展开更多
关键词 rock material rockburst proneness crack damage strength improved acoustic emission(AE)Kneedle method load/unload response ratio theory
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Evolution of mechanical parameters of Shuangjiangkou granite under different loading cycles and stress paths 认领 引用 被引量：8
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作者 Liangjie Gu Xia-Ting Feng +2 位作者 Rui Kong Chengxiang Yang Yuelin Xia 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第4期1113-1126,共14页
Surrounding rocks at different locations are generally subjected to different stress paths during the process of deep hard rock excavation.In this study,to reveal the mechanical parameters of deep surrounding rock und... Surrounding rocks at different locations are generally subjected to different stress paths during the process of deep hard rock excavation.In this study,to reveal the mechanical parameters of deep surrounding rock under different stress paths,a new cyclic loading and unloading test method for controlled true triaxial loading and unloading and principal stress direction interchange was proposed,and the evolution of mechanical parameters of Shuangjiangkou granite under different stress paths was studied,including the deformation modulus,elastic deformation increment ratios,fracture degree,cohesion and internal friction angle.Additionally,stress path coefficient was defined to characterize different stress paths,and the functional relationships among the stress path coefficient,rock fracture degree difference coefficient,cohesion and internal friction angle were obtained.The results show that during the true triaxial cyclic loading and unloading process,the deformation modulus and cohesion gradually decrease,while the internal friction angle gradually increases with increasing equivalent crack strain.The stress path coefficient is exponentially related to the rock fracture degree difference coefficient.As the stress path coefficient increases,the degrees of cohesion weakening and internal friction angle strengthening decrease linearly.During cyclic loading and unloading under true triaxial principal stress direction interchange,the direction of crack development changes,and the deformation modulus increases,while the cohesion and internal friction angle decrease slightly,indicating that the principal stress direction interchange has a strengthening effect on the surrounding rocks.Finally,the influences of the principal stress interchange direction on the stabilities of deep engineering excavation projects are discussed. 展开更多
关键词 Triaxial cyclic loading and unloading test Stress path Deformation modulus and elastic deformation increment ratios Fracture degree Cohesion and internal friction angle
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Mechanical properties and energy evolution law of water bearing sandstone under cyclic loading 认领 引用 被引量：2
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作者 SUN Xiaoming DING Jiaxu +4 位作者 HE Linsen SHI Fukun ZHANG Yong MIAO Chengyu ZHANG Jing 《Journal of Mountain Science》 SCIE CSCD 2024年第11期3913-3929,共17页
Due to excavation disturbances and the coupled hydro-mechanical effects,deep rock masses experience nonlinear large deformations in the surrounding rock,necessitating an urgent exploration of the rock damage and failu... Due to excavation disturbances and the coupled hydro-mechanical effects,deep rock masses experience nonlinear large deformations in the surrounding rock,necessitating an urgent exploration of the rock damage and failure mechanisms from the perspectives of hydro-mechanical coupling and mechanical properties.Therefore,this study conducted uniaxial cyclic loading-unloading tests on sandstone samples with different water contents(0%,0.26%,0.52%,0.78%,and 1.04%)to investigate the microstructural evolution,energy evolution laws,and failure characteristics under varying water contents and cyclic loading conditions.The main conclusions are as follows:(1)Concerning micro-pore structures,as the water content increases,the porosity and maximum pore size of the sandstone first decrease and then increase.At 0%water content,the porosity is 4.82%and the maximum pore size is 31.94μm.At 0.26%water content,both porosity and maximum pore size decrease to 3.03%and 16.15μm,respectively.When the water content reaches 1.04%,the porosity and maximum pore size increase to 14.34%and 45.99μm,respectively.(2)Regarding energy evolution laws,the energy evolution of the specimens during cyclic loading-unloading mainly converts to elastic energy,showing a step-wise increase in energy.Further analysis reveals that the water content has a significant impact on the dissipation energy coefficient of the sandstone.At lower stress levels(0.85σmax),an increase in water content leads to increased fluctuations in the dissipation energy coefficient.(3)In terms of failure characteristics,with increasing water content,the failure mode of the specimens shifts from primary crack failure to microcrack failure,corresponding to the energy evolution during cyclic loading-unloading processes. 展开更多
关键词 Cyclic loading and unloading Sandstone Mechanical property Energy evolution Pore structure
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Short-term and imminent anomalies of earthquake of load and unload response ratio of the well level to earth tides 认领 引用 被引量：2
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作者 张昭栋 陈学忠 +5 位作者 吴子泉 王梅 程烨 苏鸾声 王忠民 石荣会 《Acta Seismologica Sinica(English Edition)》 1997年第2期73-81,共9页
In this paper, through the nonlinear response of rock strain and stress, we have analized the physical mechanism of loading and unloading response ratio of the well level to the earth tides,the respouse of an aquifer ... In this paper, through the nonlinear response of rock strain and stress, we have analized the physical mechanism of loading and unloading response ratio of the well level to the earth tides,the respouse of an aquifer of confined well to bulk strain tide and showed two methods of the calculation of loading and unloading response ratio of the well level to the earth tides. We took the example of the Yu 01 well, which is near the epicenter of Heze M S 5.9 earthquake, calculated the response rate and loading and unloading response ratio of two kinds of the earth tides of it. The response rate and response ratio before the earthquake had the variation of increase. 展开更多
关键词 loading and unloading response ratio earth tide well level Heze earthquake Yu 01 well
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