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The tempo-spatial evolution characteristics of the load/unload response ratio before strong earthquakes in California of America and its predicting implications 认领 引用
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作者 宋治平 尹祥础 +2 位作者 王裕仓 徐平 薛艳 《Acta Seismologica Sinica(English Edition)》 2000年第6期628-635,共8页
In this paper, the tempo-spatial evolution characteristics of the load/unload response ratio (namely LURR or Y value) before strong earthquakes with magnitude over 6 during 1976~1994 in California of America are studi... In this paper, the tempo-spatial evolution characteristics of the load/unload response ratio (namely LURR or Y value) before strong earthquakes with magnitude over 6 during 1976~1994 in California of America are studied in detail. The results show that there appear some high-Y regions cohering with the regional tectonic trend in a great area 3~4 years before strong earthquakes and these high-Y regions migrate from the periphery to the epicenter region at a speed of tens of kilometers per year. The load/unload response ratio (LURR) anomalies near the epicenter region characterizes a type of (ascend ? descend( and appear and increase steeply until one year or less before most earthquakes. (Positive( earthquakes form usually a concentration area; in and near which the main shock occurs. We have analyzed the different and same characters of earthquakes between California of American and the Chinese mainland. Basing on these results, we discuss the approach and method how to predict and estimate the three parameters (place, time and magnitude) of a strong earthquake in California of American by applying the characteristics of the LURR. 展开更多
关键词 California of American the load/unload response ratio prediction method
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The spatial temporal evolution characteristics of the load/unload response ratio(LURR) and its implications for predicting the three elements of earthquakes 认领 引用
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作者 宋治平 尹祥础 陈学忠 《Acta Seismologica Sinica(English Edition)》 1996年第2期235-244,共10页
The spatial temPOral evolution characteristics of the load/unload response ratio (Y) before strong earthquakes is studied in this paper. The results show that the regions of high value of Y migrate and converge to the... The spatial temPOral evolution characteristics of the load/unload response ratio (Y) before strong earthquakes is studied in this paper. The results show that the regions of high value of Y migrate and converge to the impending earthquake epicenter from different directions before the occurrence of the event. Basing on this discovery, it is proposed that the method can be used to predict the three elements of an earthquake. It was applied to predict that an earthquake would occur in the western part of Yunnan Province, southwestern China. The three elements (time, space and magnitude) of the Menglian earthquake with Ms7.3 which occurred on July 12, 1995 in Yunnan Province tallied with our prediction. 展开更多
关键词 load/unload resPOnse ratio (LURR ) time-space evolution of LURR three elements of earthquakes earthquake prediction.
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Investigation on the Load/Unload Response Ratio With Coda Q-1 as Response 认领 引用
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作者 Chen Xuezhong,Yin Xiangchu,Aki K,Ouyang H,Jin A.,Song Zhiping,and Wang YucangCenter tor Analysis and Prediction,SSB,Beijing 100036,ChinaSouthern California Eanhquake Center,University of Southern California,Los Angeles,USAInstitute of Geophysics,SSB,Beijing 100081,China 《Earthquake Research in China》 1996年第4期38-45,共8页
The load/unload response ratio YQ with the geophysical parameter coda Q-1 of the crust as response is denned in this study.The variation in YQ-1 before and after the Northridge earthquake of January 17,1994(California... The load/unload response ratio YQ with the geophysical parameter coda Q-1 of the crust as response is denned in this study.The variation in YQ-1 before and after the Northridge earthquake of January 17,1994(California)has been investigated by using the data of coda Q-1 with frequencies of 1.5,3.0,6.0,12.0,and 24.0 Hz in the Southern California from 1987 to 1994.It can be found that YQ-1 for coda waves with all frequencies,the frequency of 12.0 Hz excluded,ascended to a certain extent prior to the occurrence of the rnainshock and returned to normality after the main shock. 展开更多
关键词 Coda Q-1 Theory of the load/unload response ratio Load/unload response ratio YQ The Northridge earthquake Earthquake prediction
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Experimental Research on the Load/Unload Response Ratio (LURR) Theory 认领 引用 被引量：1
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作者 YuHuaizhong YinXiangchu +8 位作者 LiangNaigang XiaMengfen LiMin XuZhaoyong PengKeyin VictorKukshenko WuZhishen QiLi SurgueiElizarov 《Earthquake Research in China》 2003年第3期227-235,共9页
Implementing acoustic emission experiments with large rock samples, LURR (Load/Unload Response Ratio) theory was studied. The loading conditions in the experiments were designed to simulate the complicated loading pro... Implementing acoustic emission experiments with large rock samples, LURR (Load/Unload Response Ratio) theory was studied. The loading conditions in the experiments were designed to simulate the complicated loading process of underground rocks. The damages emerging inside the rock samples were recorded by the acoustic emission technique during the loading process. The experimental results were consistent with prediction by LURR theory. Integrating the changing processes of LURR value Y and the location process of acoustic emission events showed agreement between the variation of LURR value Y and the damage evolution inside the rocks. Furthermore, the high value of Y emerged before the complete breakdown of materials. Therefore, the damage evolution of rock specimen can be quantitatively analyzed with LURR theory, thus the failure of the rock materials and the earthquake occurrence may be predicted. The experimental results gave a further verification of LURR theory. 展开更多
关键词 Load/Unload Response Ratio Acoustic emission Circling load Large sample Critical sensitivity
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Physical meaning and prediction efficiency of the load/unload response ratio of rocks in strain-weakening phase before failure 认领 引用
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作者 许昭永 杨润海 +3 位作者 王彬 赵晋明 王赟赟 梅世蓉 《Acta Seismologica Sinica(English Edition)》 2002年第1期47-55,共9页
Rock experiment results indicate that the load/unload response ratio (LURR) of rocks expressed via strain energy may have singular or negative value after the stress in the rock reaches its maximum before rock failure... Rock experiment results indicate that the load/unload response ratio (LURR) of rocks expressed via strain energy may have singular or negative value after the stress in the rock reaches its maximum before rock failure or when the rock goes into the strain-weakening phase. The universality of this phenomenon is discussed. Expressed via strain or strain energy and the travel time of P wave, the variation form of the reciprocal of LURR during the process of rock failure preparation is derived. The results show that after a sharp decrease the reciprocal of LURR reaches its minimum when the main fracture of the rock is about to appear. This feature can be taken as an indication that the rock main fracture is impending. 展开更多
关键词 strain-weakening phase load/unload response ratio prediction efficiency
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Variation of the Load/Unload Response Ratio Before the Main Shocks of the Reservoir-Induced Earthquakes 认领 引用
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作者 Chen Xuezhong and Yin XiangchuInstitute of Geophysics, SSB, Beijing 100081, ChinaCenter for Analysis and Predicuon, SSB, Beijing 100036, China 《Earthquake Research in China》 1996年第2期27-35,共9页
In this paper, the theory of the load/unload response ratio is applied to the prediction of the reservoir-induced earthquakes, and variation of the load/unload response ratio Y preceding the occurrence of main shocks ... In this paper, the theory of the load/unload response ratio is applied to the prediction of the reservoir-induced earthquakes, and variation of the load/unload response ratio Y preceding the occurrence of main shocks of the reservoir-induced earthquakes in Xinfengjiang, Foziling, Danjiangkou, and Shenwo. The results show that the load/unload response ratio Y rises evidently prior to the main shocks. 展开更多
关键词 Load/unload response ratio Reservoir earthquake Earthquake prediction Nonlinear theory
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Application of the Load/Unload Response Ratio Theory to Predictions of Moderate Earthquakes (7.0>M≥6.0) 认领 引用
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作者 Chen Xuezhong and Yin XiangchuInstitute of Geophysics,SSB,Beijing 100081 ChinaCenter for Analysis and Prediction,SSB,Beijing 100036 China 《Earthquake Research in China》 1995年第3期7-12,共6页
The variation in load/unload response ratio before some moderate earthquakes is analyzed based on the theory of the load/unload response ratio.The results show that the load-unload response ratio increases noticeably ... The variation in load/unload response ratio before some moderate earthquakes is analyzed based on the theory of the load/unload response ratio.The results show that the load-unload response ratio increases noticeably before moderate earthquakes,and there are three kinds of patterns in which the load/unload response ratio varies and the duration of noticeable increase in load/unload response ratio ranges from half a year to two years. 展开更多
关键词 Earthquake prediction load/unload response ratio Nonlinear theory
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The Experimental Simulation of Rocks on Load/Unload Response Ratio for Earthquake Prediction 认领 引用 被引量：3
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作者 Wang Yucang, Yin Xiangchu, and Wang HaitaoLaboratory for Non-linear Mechanics of Continuous Media , Institute of Mechanics,Chinese Academy of Sciences, Beijing 100080, ChinaLaboratory for Non-linear Mechanics of Continuous Media , Institute of Mechanics,Chinese Academy of Sciences, Beijing 100080, ChinaCenter for Analysis and Prediction , CSB, Beijing 100036, China 《Earthquake Research in China》 1998年第4期40-45,共6页
The load/unload experiments on rock failure under pressure have been carried out in Material Test System (MTS) in the Laboratory for Non-linear Mechanics of Continuous Media (LNM), Institute of Mechanics, Chinese Acad... The load/unload experiments on rock failure under pressure have been carried out in Material Test System (MTS) in the Laboratory for Non-linear Mechanics of Continuous Media (LNM), Institute of Mechanics, Chinese Academy of Sciences, and load/unload response ratio (LURR) values with strain as response (i.e. inverse elastic constant as response rate) have been obtained. The experimental results are in accordance with theoretical results and those in real earthquakes: LURR rises just before rock failure. So LURR can be used as the precursor of rock failure and earthquake prediction. 展开更多
关键词 Load\Unload Response Ratio Experiment of rock failure Earthquake prediction.
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Frictional characteristics of rough granite fractures subjected to various normal loading/unloading rates and shear velocities 认领 引用
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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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Characterization of rock damage evolution and support timing under true triaxial unloading paths 认领 引用
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作者 QI Min-jie ZHAO Guang-ming +6 位作者 MENG Xiang-rui LIU Chong-yan XU Wen-song XU Xin ZHAO Cong-hui SUN Kai ZHAO Bin 《Journal of Central South University》 SCIE EI CAS CSCD 2026年第1期442-465,共24页
To study the influence of support timing and support strength on the mechanical properties and deformation damage characteristics of a single-sided unloaded rock mass,a true triaxial perturbation unloaded rock testing... To study the influence of support timing and support strength on the mechanical properties and deformation damage characteristics of a single-sided unloaded rock mass,a true triaxial perturbation unloaded rock testing system was used to conduct rock damage tests on sandstone with different support timing and strength paths.Based on the acoustic emission monitoring system,the spatial and temporal evolution characteristics of the whole process of rock body loaded instability under two stress paths were studied,and the mechanism of the reinforcing effect of stress support on the unloaded rock mass was analyzed.The results show that,within the scope of this study,both earlier applications of shoring and an increase in shoring strength can effectively improve the ultimate bearing capacity of the unloaded rock,which increases the ultimate bearing capacity of the unloaded rock mass by 60.31% and 54.96%,respectively;There is a phenomenon of rebound deformation of the rock mass during sudden changes in stress(single-sided unloading,stress support),which shows opposite expansion and compression platforms on the stress−strain curve;The crack evolution of unloaded rock under different stress support conditions shows the state law of"initial crack activation→middle steady state expansion→late main crack penetration",and the lagging support significantly accelerates the crack evolution from local activation to main penetration;The single-sided unloading and stress-supporting stages have less influence on the unloading deformationsσ1u,σ2u and support deformationsσ1 t,σ2t in theσ1 andσ2directions,while they show significant response characteristics toσ3u,σvu and σ3 t,σvt,and with the increase of the support strength,the stress-supporting stagesσ3 t,σvt gradually increase and exceed the deformations generated by the unloading stagesσ3u,σvu;The increase of support strength can effectively compensate for the rock stress loss caused by unloading,which makes the maximum,minimum,and volumetric strain support coefficients during the loading and unloading of the rock body increase gradually while the effect on the intermediate principal strain support coefficient is small;During loading,the support strength of rock masses seeks a new bearing area by regulating stress equilibrium states.This process primarily manifests as a shift in the locations of the crushing zone and the main bearing area,accompanied by a corresponding transformation in failure patterns.Consequently,the rock mass transitions from asymmetric three-zone damage under no or weak support to approximate symmetric three-zone damage under strong support.Simultaneously,the main load-bearing area of the rock mass shifts from deep bearing in the unsupported to middle bearing under strong support as the support strength increases. 展开更多
关键词 true triaxial single-sided unloading unloading effect support timing support strength
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Anisotropic mechanical behaviour of Callovo-Oxfordian claystone under triaxial lateral unloading 认领 引用
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作者 Hao Wang Yu-Jun Cui +2 位作者 Patrick Dangla Minh Ngoc Vu Jean Talandier 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2026年第5期3882-3890,共9页
Callovo-Oxfordian(COx)claystone has been selected as the host rock formation for the deep geological disposal of radioactive waste in France,called the Cigéo project.The excavation of drifts in the COx formation ... Callovo-Oxfordian(COx)claystone has been selected as the host rock formation for the deep geological disposal of radioactive waste in France,called the Cigéo project.The excavation of drifts in the COx formation induced damage zones with an anisotropic shape,while the stress state around the drifts is almost isotropic.This is due to the anisotropic properties of the host rock formation and the instability caused by the brittle damage.In this study,the mechanical anisotropy of COx claystone was investigated through a triaxial shear test,where the axial stress was maintained while the lateral stress was decreased.Such a method was proposed for simulating one of the possible unloading paths involved during the excavation.The triaxial samples were prepared along different directions based on the angle between the axial loading direction and the one perpendicular to the bedding plane.Results show that the stress-strain curve exhibited an elasto-plastic pattern.With increasing deviatoric stress,a minor decline in Young's modulus E was observed,suggesting progressive damage behaviour.The shear strength changed with increasing the loading angle,showing the anisotropic property of COx claystone.Moreover,the results in this study and collected from other works show a time-dependent behaviour of COx claystone.It is attributed to the coupled effect of creep and pore pressure dissipation inside claystone. 展开更多
关键词 Callovo-Oxfordian claystone Triaxial unloading Anisotropy Young's modulus Shear strength Cigéo
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Damage evolution law under unloading confining pressure of cemented backfill based on energy dissipation 认领 引用
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作者 LIU Wei-zhen GONG Bin +3 位作者 NIU Shi-wei WANG Hui-qin LI Hong-rui HU Zhong-jing 《Journal of Central South University》 SCIE EI CAS CSCD 2026年第1期400-421,共22页
High ground temperature and unloading disturbance have emerged as critical factors impacting the property of cemented gauge-fly ash backfill(CGFB).The characteristics of energy and damage in CGFB were analyzed under c... High ground temperature and unloading disturbance have emerged as critical factors impacting the property of cemented gauge-fly ash backfill(CGFB).The characteristics of energy and damage in CGFB were analyzed under conditions of high ground temperature and unloading by conducting triaxial unloading tests with different initial confining pressures on CGFB that had been cured at various temperatures.Based on dissipative energy,triaxial unloading confining pressure damage constitutive model of CGFB was constructed.It has been demonstrated that the ratio of elastic strain energy in CGFB decreases and the ratio of dissipated energy increases at the end of unloading increases under higher curing temperature.The change in the elastic energy consumption ratio curve of CGFB,which shifts from a gradual increase to a swift rise at a certain"inflection point",can be utilized as a criterion for evaluating the failure of the unloading strength of CGFB.The triaxial unloading damage constitutive model for CGFB divides the damage progression into three distinct phases:initial damage stage,accelerated damage development stage,and rapid damage growth stage.The research findings offer a theoretical foundation for evaluating the extent of damage to CGFB caused by the combined influences of elevated ground temperature and unloading. 展开更多
关键词 curing temperature cemented gangue-fly ash backfill unloading confining pressure dissipated energy damage constitutive model
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Failure characteristics and the energy criterion of rock with a through-going joint under true-triaxial unloading conditions:Insights from the DEM model 认领 引用
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作者 Fei Liu Changhui Liang +2 位作者 Sijia Liu Yongjun Zhang Luo Wang 《Deep Underground Science and Engineering》 EI CAS CSCD 2026年第2期465-481,共17页
Excavation unloading damages rock masses,with preferential failure along geological defects in rock engineering,which may induce catastrophe geological hazards.It is important to study the failure of jointed rock unde... Excavation unloading damages rock masses,with preferential failure along geological defects in rock engineering,which may induce catastrophe geological hazards.It is important to study the failure of jointed rock under true-triaxial unloading conditions.3D DEM true-triaxial unloading modeling tests on rock with through-going joint considering the contributing factors,that is,the joint inclination,the initial confining pressure,and the unloading point,were conducted to study the rock mechanical properties,cracking behaviors,and failure characteristics.Six typical rock failure modes were summarized based on the development of main cracks,and the associated cracking mechanisms were studied by analysis of the ratio of tensile crack to shear crack.An energy criterion determining whether unloading-induced rock failure occurs instantaneously was proposed by comparing the accumulated elastic strain energy at the unloading point in true-triaxial unloading simulations with the limit elastic strain energy stored in rocks in biaxial compression modeling tests.Furthermore,the strength characteristics and applicability of the Mogi–Coulomb failure criterion in describing the failure of specimens with through-going joint under true-triaxial unloading conditions were studied.This study provides some new insights into true-triaxial unloading-induced failure of jointed rock,which may be valuable for revealing the mechanism of rock instabilities influenced by geological defects in deep excavations. 展开更多
关键词 cracking behavior energy criterion joint rock failure mode true-triaxial unloading modeling test
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Loading-unloading responses of non-persistent flawed granite subjected to cyclic disturbances 认领 引用
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作者 Tingting Liu Chao Zhang +3 位作者 Luyang Ding Kun Xu Xinping Li Wenxu Huang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2026年第5期3589-3605,共17页
During geotechnical construction,flawed rock masses experience dynamic cyclic disturbances,leading to cumulative deformation and progressive damage.Consequently,elucidating the fracture mechanisms under cyclic loading... During geotechnical construction,flawed rock masses experience dynamic cyclic disturbances,leading to cumulative deformation and progressive damage.Consequently,elucidating the fracture mechanisms under cyclic loading is crucial for ensuring the safety and prolonged operation of deep underground engineering.This study investigated the mechanical responses of the surrounding rock at different locations by conducting triaxial tests on flawed granite using three distinct cyclic loading and unloading paths.Based on the maximum tangential stress criterion,a fracture mechanics model for open flaws was developed to analyze the intrinsic influence of confining pressure and flaw inclination on crack initiation behavior.The results indicate that graded unloading of confining pressure significantly weakens the flawed rock mass,reducing its peak stress to only 77.5%of that observed under constant confining pressure.Conversely,flawed rock masses exhibit a substantial increase in bearing capacity under increasing graded cyclic loading,achieving a peak stress 19.3%higher than that under cyclic disturbance loading.At a constant confining pressure of 40 MPa,the type of disturbance loading has no significant effect on the failure mode.The flawed granite specimens form a nearly V-shaped shear failure zone along the open flaw.However,confining pressure unloading induced a more complex shear-tensile composite failure mode in the specimens.The crack initiation angle increases nonlinearly with confining pressure,but decreases gradually as the flaw inclination angle(β)increases.These findings provide valuable insights for the safe construction of deep underground engineering. 展开更多
关键词 Flawed granite Cyclic disturbance loading Energy evolution Fracture mechanism Crack initiation angle
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Mechanical behavior and acoustic emission characteristics of initially damaged coal under triaxial cyclic loading and unloading 认领 引用 被引量：2
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作者 Qican Ran Yunpei Liang +5 位作者 Quanle Zou Chunfeng Ye Zihan Chen Tengfei Ma Zhaopeng Wu Bichuan Zhang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2026年第1期230-245,共16页
During deep coal mining,an instability failure of coal usually occurs under the combined effect of initial damage and triaxial cyclic loading and unloading(TCLU).Therefore,this study investigated the impact of initial... During deep coal mining,an instability failure of coal usually occurs under the combined effect of initial damage and triaxial cyclic loading and unloading(TCLU).Therefore,this study investigated the impact of initial damage on mechanical behavior and acoustic emission(AE)characteristics of coal under TCLU.Initial damage variables(IDVs)of coal specimens were quantified using preloading,followed by TCLU experiments to assess the deformation,energy distribution,and fracture development.The results revealed that the increase in IDVs significantly reduced the structural integrity of coal specimens,increased the cumulative irreversible strain,and enhanced the dissipated energy owing to microfracture expansion.Moreover,AE monitoring showed earlier activation of fractures and a higher occurrence of large-scale rupture events of coal specimens with high IDVs,which correlated with decreasing AE b values(reflecting the different scales of fracture within specimens)and increasing S values(reflecting the AE activity within specimens).Additionally,computed tomography analysis revealed intensified fracture networks and increasing three-dimensional fractal dimensions of coal specimens with higher IDVs.Finally,the coupling effect of TCLU and initial damage on the weakening mechanism of coal was investigated.Initial damage significantly reduced the structural integrity of coal by increasing the number of weak planes within coal specimens,contributing to the earlier activation and rapid expansion of fractures at low stress levels under TCLU and eventually accelerating the weakening process of coal.This study provides a scientific basis and theoretical support for the prevention and control of dynamic disasters in deep coal mining. 展开更多
关键词 Triaxial cyclic loading Initially damaged coal Linear energy storage(LES) Acoustic emission(AE) Computed tomography(CT)
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Analysis of rock burst ejection behavior and stress-energy response of coal under true triaxial loading-unloading conditions 认领 引用
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作者 XU Wen-tao CHENG Yun-hai +1 位作者 XU Wen-song PAN Cheng 《Journal of Central South University》 SCIE EI CAS CSCD 2026年第5期2210-2230,共21页
In order to explore the ejection failure mechanism and energy variation law of the in-focused energy rock burst and the concentrated stress rock burst,based on the true triaxial disturbance unloading rock test system,... In order to explore the ejection failure mechanism and energy variation law of the in-focused energy rock burst and the concentrated stress rock burst,based on the true triaxial disturbance unloading rock test system,high-stress unloading and different second principal stress loading tests were conducted.The mechanical properties and AE characteristics of coal samples under high-stress unloading and varying secondary principal stress loading conditions have been systematically analyzed.The energy of the loaded coal sample was calculated by the area of the loading and unloading curve.The elastic energy and dissipation energy ratio,the pre-peak energy and post-peak energy ratio,and the dissipation energy and elastic energy ratio are used to characterize the energy accumulation,dissipation,and release behavior.The energy mutation mechanism of coal samples under different loading and unloading conditions is revealed.The results indicate that the ejection failure characteristics exhibit the characteristics of tension-shear composite failure,in which tension failure is an inevitable occurrence during the ejection failure process.Unloading is more sensitive to energy accumulation ejection failure,and the ejection failure phenomenon tends to become more evident as the unloading degree deepens.The second principal stress has a great influence on the ejection failure of stress concentration rock burst,and the intensity of ejection failure increases with the increase of the second principal stress.The energy variation law of coal samples under high stress unloading and different second principal stress loading conditions is similar.With the increase in coal sample strength,the kinetic energy,impact tendency,and ejection failure probability of coal sample ejection fragments also increase.The more fully damaged after unloading,the more prone to ejection.The evolution characteristics of AE have three stages,i.e.,rising period,quiet period,and destruction,in which the local ejection phenomenon appears in the destruction stage.The research method is a certain rationality for the analysis of the energy evolution mechanism of coal rock.The research results provide an experimental basis for the ejection failure of rock bursts and support for targeted classified control measures. 展开更多
关键词 deep coal mass true triaxial different principal stresses unloading rock burst
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Mechanical response characteristics and damage evolution mechanisms of deep rock masses under coupled loading-unloading-support-disturbance effects 认领 引用
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作者 Minjie Qi Guangming Zhao +5 位作者 Xiangrui Meng Chongyan Liu Wensong Xu Longpei Ma Xin Xu Yaoyuan Zhang 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2026年第8期1655-1673,共19页
To reveal the mechanical response characteristics of deep rock masses under the complete engineering disturbance chain of "stress loading,excavation unloading,support reinforcement,and cyclic disturbance,"th... To reveal the mechanical response characteristics of deep rock masses under the complete engineering disturbance chain of "stress loading,excavation unloading,support reinforcement,and cyclic disturbance,"this study employed a true triaxial testing system combined with acoustic emission monitoring to conduct rock mass failure tests under coupled loading-unloading-support-disturbance actions.Results indicate that unloading is the dominant factor inducing rock mass damage and degradation,reducing strength by 31.57%compared to static loading.The superimposed disturbance effect further decreases the strength by 17.40%.Support partially restored rock strength and stiffness,increasing them by 7.29%and 10.37%,respectively,compared with pure unloading.Unloading increased dissipated energy per stress increment,and support achieved a dual effect of"energy dissipation and damage suppression"by inhibiting repeated crack reopening.Along the undisturbed path,damage accumulated slowly early and then exhibits a concentrated late-stage jump.Under disturbance,damage followed an"increase during loading,gradual change during unloading,and sharp surge at failure" pattern,with a markedly smaller rise in the damage variable at final instability than under the undisturbed path.Under disturbed conditions,intact rock showed the Kaiser effect,whereas unloaded rock subsequently exhibited the Felicity effect,supporting delayed Felicity onset,enhancing stress memory and disturbance resistance. 展开更多
关键词 True triaxial Single side unloading Cyclic disturbance Acoustic emission Mechanical response
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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
19
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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True triaxial unloading test on the mechanical behaviors of sandstone:Effects of the intermediate principal stress and structural plane 认领 引用 被引量：2
20
作者 Fan Feng Zhiwei Xie +3 位作者 Shaojie Chen Diyuan Li Siyu Peng Tong Zhang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2025年第4期2208-2226,共19页
A series of true triaxial unloading tests are conducted on sandstone specimens with a single structural plane to investigate their mechanical behaviors and failure characteristics under different in situ stress states... A series of true triaxial unloading tests are conducted on sandstone specimens with a single structural plane to investigate their mechanical behaviors and failure characteristics under different in situ stress states.The experimental results indicate that the dip angle of structural plane(θ)and the intermediate principal stress(σ2)have an important influence on the peak strength,cracking mode,and rockburst severity.The peak strength exhibits a first increase and then decrease as a function ofσ2 for a constantθ.However,whenσ2 is constant,the maximum peak strength is obtained atθof 90°,and the minimum peak strength is obtained atθof 30°or 45°.For the case of an inclined structural plane,the crack type at the tips of structural plane transforms from a mix of wing and anti-wing cracks to wing cracks with an increase inσ2,while the crack type around the tips of structural plane is always anti-wing cracks for the vertical structural plane,accompanied by a series of tensile cracks besides.The specimens with structural plane do not undergo slabbing failure regardless ofθ,and always exhibit composite tensile-shear failure whatever theσ2 value is.With an increase inσ2 andθ,the intensity of the rockburst is consistent with the tendency of the peak strength.By analyzing the relationship between the cohesion(c),internal friction angle(φ),andθin sandstone specimens,we incorporateθinto the true triaxial unloading strength criterion,and propose a modified linear Mogi-Coulomb criterion.Moreover,the crack propagation mechanism at the tips of structural plane,and closure degree of the structural plane under true triaxial unloading conditions are also discussed and summarized.This study provides theoretical guidance for stability assessment of surrounding rocks containing geological structures in deep complex stress environments. 展开更多
关键词 True triaxial unloading Dip angle of structural plane Intermediate principal stress Mechanical behaviors Cracking modes Failure criterion
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