Accurate prediction of rockburst intensity levels is crucial for ensuring the safety of deep hard rock engineering construction.This paper introduced an expert system for rockburst intensity level prediction that empl...Accurate prediction of rockburst intensity levels is crucial for ensuring the safety of deep hard rock engineering construction.This paper introduced an expert system for rockburst intensity level prediction that employs machine learning algorithms as the basis for its inference rules.The system comprises four modules:a database,a repository,an inference engine,and an interpreter.A database containing 1114 rockburst cases was used to construct 357 datasets that serve as the repository for the expert system.Additionally,19 types of machine learning algorithms were used to establish 6783 micro-models to construct cognitive rules within the inference engine.By integrating probability theory and marginal analysis,a fuzzy scoring method based on the SoftMax function was developed and applied to the interpreter for rockburst intensity level prediction,effectively restoring the continuity of rockburst characteristics.The research results indicate that ensemble algorithms based on decision trees are more effective in capturing the characteristics of rockburst.Key factors for accurate prediction of rockburst intensity include uniaxial compressive strength,elastic energy index,the maximum principal stress,tangential stress,and their composite indicators.The accuracy of the proposed rockburst intensity level prediction expert system was verified using 20 engineering rockburst cases,with predictions aligning closely with the actual rockburst intensity levels.展开更多
To investigate the energy relief effect of real-time drilling in preventing rockburst in high-stress rock,a series of high-stress real-time drilling uniaxial compression tests were conducted on red sandstone specimens...To investigate the energy relief effect of real-time drilling in preventing rockburst in high-stress rock,a series of high-stress real-time drilling uniaxial compression tests were conducted on red sandstone specimens using the SG4500 drilling rig.Results showed that the mechanical behavior(i.e.peak strength and rockburst intensity)of the rock was weakened under high-stress real-time drilling and exhibited a downward trend as the drilling diameter increased.The real-time drilling energy dissipation index(ERD)was proposed to characterize the energy relief during high-stress real-time drilling.The ERD exhibited a linear increase with the real-time drilling diameter.Furthermore,the elastic strain energy of post-drilling rock showed a linear relationship with the square of stress across different stress levels,which also applied to the peak elastic strain energy and the square of peak stress.This findingreveals the intrinsic link between the weakening effect of peak elastic strain energy and peak strength due to high-stress real-time drilling,confirmingthe consistency between energy relief and pressure relief effects.By establishing relationships among rockburst proneness,peak elastic strain energy,and peak strength,it was demonstrated that high-stress real-time drilling reduces rockburst proneness through energy dissipation.Specifically,both peak elastic strain energy and rockburst proneness decreased with larger drill bit diameters,consistent with reductions in peak strength,rockburst intensity,and fractal dimensions of high-stress real-time drilled rock.These results validate the energy relief mechanism of real-time drilling in mitigating rockburst risks.展开更多
0 INTRODUCTION Due to the sudden and highly destructive nature of slope rock collapse,developing effective early warning systems has become an urgent challenge in geotechnical engineering(Cai and Detournay,2024;Loew e...0 INTRODUCTION Due to the sudden and highly destructive nature of slope rock collapse,developing effective early warning systems has become an urgent challenge in geotechnical engineering(Cai and Detournay,2024;Loew et al.,2017).Traditional monitoring methods primarily target the acceleration stage preceding disasters(such as displacement monitoring for landslides and debris flows),which is effective for early warning of plastic collapse disasters but often inadequate for brittle failure modes(Walter et al.,2019;Chao et al.,2018;Crosta et al.,2017).展开更多
Efficient hard-rock fragmentation remains a critical challenge in mechanized mining.This study designed an adjustable-spacing mold and conducted double cutting pick indentation tests on granite.Mechanical responses an...Efficient hard-rock fragmentation remains a critical challenge in mechanized mining.This study designed an adjustable-spacing mold and conducted double cutting pick indentation tests on granite.Mechanical responses and fragmentation characteristics under varying horizontal stresses,pick spacings,and groove depths were systematically analyzed.Unidirectional stress concentration altered the rock fragmentation modes,exhibiting a dual effect on the fragmentation process.The maximum indentation force(F_(max)),indentation hardness index(IHI),indentation modulus(IM),and indentation energy(W)initially increased and then decreased with rising horizontal stress.Appropriate spacing promoted radial crack coalescence,whereas too small a spacing(20 mm)caused repetitive re-fragmentation of rock chips,and too large a spacing(50 mm)resulted in unbroken ridges.Pre-cut grooves weakened the rock,reducing F_(max) and specific energy(SE),thus improving fragmentation efficiency,although the improvement slowed beyond a 10-mm groove depth.Based on the results and rock-mass conditioning assisted fragmentation mechanism,a“stress-structure dual control”assisted fragmentation mechanism was proposed,and a“pre-drilling unloading−alternate stopping”mining scheme was exploratorily designed.This approach creates favorable conditions for rock fragmentation by reducing stress levels and rock mass integrity in target zones,providing theoretical support and an engineering paradigm for mecheanized mining of deep resources.展开更多
Water storage in the Three Gorges Reservoir in China has increased the regional microseismicity.Bedding-rock landslides,one of the most common slope structures in the Three Gorges Reservoir,are highly prone to sliding...Water storage in the Three Gorges Reservoir in China has increased the regional microseismicity.Bedding-rock landslides,one of the most common slope structures in the Three Gorges Reservoir,are highly prone to sliding under seismic loading.Existing research primarily focuses on the stability of bedding rock landslides under strong earthquakes,while studies on the cumulative damage and long-term stability of bedding rock landslides under high-frequency microseismicity remain immature.In this study,we considered bedding rock landslides under high-frequency microseismicity in the Three Gorges Reservoir area as the research subject and equivalent microseismicity as pre-peak cyclic loading.First,we analyzed the shear strength deterioration of rock mass structural planes under pre-peak cyclic loading conditions and found that the deformation and failure of structural planes involve contact and damage effects.The shear strength of the rock mass structural planes under pre-peak cyclic loading conditions is affected by the confining pressure,loading rate,loading amplitude,and number of loading cycles.Among these factors,the shear strength of the structural planes was the most sensitive to the number of loading cycles.As the number of cycles increased,the rock mass structural planes underwent three stages:stress adjustment(increase in shear strength),fatigue damage(gradual decrease in shear strength),and structural failure(rapid decrease in shear strength).The stability of bedding rock landslides under high-frequency microseismicity was analyzed,revealing that the stability of bedding rock landslides under high-frequency microseismicity can be divided into three stages:short-term enhancement,gradual degradation,and rapid deterioration,exhibiting characteristics of gradual and sudden changes.展开更多
椎间盘由髓核、纤维环和软骨终板组成,对维持脊柱正常生理功能至关重要。椎间盘退变(intervertebral disc degeneration,IDD)是导致腰背痛等脊柱退行性疾病的主要病理基础,给人们的健康状况造成极大的困扰。然而目前对IDD的分子机制仍...椎间盘由髓核、纤维环和软骨终板组成,对维持脊柱正常生理功能至关重要。椎间盘退变(intervertebral disc degeneration,IDD)是导致腰背痛等脊柱退行性疾病的主要病理基础,给人们的健康状况造成极大的困扰。然而目前对IDD的分子机制仍然缺乏清晰的了解,导致缺乏有效的靶向干预措施。RAS同源家族成员A(RAS homolog family member A,RhoA)/Rho相关蛋白激酶(Rho-associated protein kinase,ROCK)信号通路是调节细胞收缩、迁移和生长的经典通路。其被激活后可参与调控细胞骨架重塑、细胞外基质代谢、生物钟节律、细胞表型改变、细胞衰老及死亡等环节,进而影响IDD的病理进程。深入探究RhoA/ROCK信号通路在IDD中的作用,不仅能揭示疾病发生的分子生物学机制,也有望为研发靶向该通路的治疗策略提供理论依据。展开更多
1.Objective The Songliao Basin(SB)is situated on the eastern margin of Eurasia continent(Northeast Asia).During the Late Jurassic to Early Cretaceous,hundreds of rifting basins developed in this area,and the SB is a u...1.Objective The Songliao Basin(SB)is situated on the eastern margin of Eurasia continent(Northeast Asia).During the Late Jurassic to Early Cretaceous,hundreds of rifting basins developed in this area,and the SB is a unique case among them as it evolved into the largest rift basin.The rift basin filling of SB includes Huoshiling Formation,Shahezi Formation,and Yingcheng Formation in ascending order.The mega-rifting was controlled by the Mongol-Okhotsk Collisional Belt to the north and northwest and the Pacific Subduction Zone to the east(Wang PJ et al.,2016).As the first rifting succession,the Huoshiling Formation contains key information about the formation of the rifting basins and records the evolution of the Mongol-Okhotsk Collisional Belt and the Pacific Subduction Zone.However,the geological period of the Huoshiling Formation has not been well constrained for two main reasons.First,it is easily confused with the Yingcheng Formation,as both are dominated by volcanogenic-sedimentary successions.Second,there is lack of reliable dating samples from the uppermost part of the Huoshiling Formation due to its considerable burial depth.展开更多
Rockbursts, which mainly affect mining roadways, are dynamic disasters arising from the surrounding rock under high stress. Understanding the interaction between supports and the surrounding rock is necessary for effe...Rockbursts, which mainly affect mining roadways, are dynamic disasters arising from the surrounding rock under high stress. Understanding the interaction between supports and the surrounding rock is necessary for effective rockburst control. In this study, the squeezing behavior of the surrounding rock is analyzed in rockburst roadways, and a mechanical model of rockbursts is established considering the dynamic support stress, thus deriving formulas and providing characteristic curves for describing the interaction between the support and surrounding rock. Design principles and parameters of supports for rockburst control are proposed. The results show that only when the geostress magnitude exceeds a critical value can it drive the formation of rockburst conditions. The main factors influencing the convergence response and rockburst occurrence around roadways are geostress, rock brittleness, uniaxial compressive strength, and roadway excavation size. Roadway support devices can play a role in controlling rockburst by suppressing the squeezing evolution of the surrounding rock towards instability points of rockburst. Further, the higher the strength and the longer the impact stroke of support devices with constant resistance, the more easily multiple balance points can be formed with the surrounding rock to control rockburst occurrence. Supports with long impact stroke allow adaptation to varying geostress levels around the roadway, aiding in rockburst control. The results offer a quantitative method for designing support systems for rockburst-prone roadways. The design criterion of supports is determined by the intersection between the convergence curve of the surrounding rock and the squeezing deformation curve of the support devices.展开更多
Delineating sweet spots is critical for the exploration and production of oil and gas in deep and tight sand reservoirs.The lack of advanced and reliable methods makes this a challenge for geologists and geophysicists...Delineating sweet spots is critical for the exploration and production of oil and gas in deep and tight sand reservoirs.The lack of advanced and reliable methods makes this a challenge for geologists and geophysicists.This study introduces,for the first time,an integrated workflow that combines pre-stack seismic inversion with rock physics modeling to predict reservoir porosity and shale volume(V-shale)for sweet spot identification in tight sand reservoirs.A new elastic parameter,the density calculation index(DCI),is introduced which links acoustic and shear impedance for seismic density inversion,thereby addressing the long-standing problem of poor density inversion accuracy.A novel combined Sun–Walsh rock physics model,developed as part of this study,significantly improves V-shale evaluation from seismic data.The proposed three-step seismic inversion approach includes:(1)deriving acoustic and shear impedance from angle-stack seismic data using model-based inversion;(2)calculating density using shear impedance constrained by DCI,followed by porosity estimation from the density–porosity relation;and(3)evaluating V-shale using theα-parameter derived from the Sun–Walsh model and pre-stack inversion results.This integrated workflow provides an effective tool for building accurate 3D reservoir models,and is especially applicable to deep,low-porosity,tight sand reservoirs worldwide.展开更多
Microseismic(MS)monitoring is an effective technique to detect mining-induced rock fractures.However,recognizing grouting-induced signals is challenging due to complex geological conditions in deep rock plates.Therefo...Microseismic(MS)monitoring is an effective technique to detect mining-induced rock fractures.However,recognizing grouting-induced signals is challenging due to complex geological conditions in deep rock plates.Therefore,a hybrid model(WM-ResNet50)integrating data enhancement,a deep convolutional neural network(CNN),and convolutional block attention modules(CBAM)was proposed.Firstly,an MS system was established at the Xieqiao coal mine in Anhui Province,China.MS waveforms and injection parameters were acquired during grouting.Secondly,signals were categorized based on time-frequency characteristics to build a dataset,which was divided into training,validation,and test sets at a ratio of 4:1:1.Subsequently,the performance of WM-ResNet50 was evaluated based on indices such as individual precision,total accuracy,recall,and loss function.The results indicated that WMResNet50 achieved an average recognition accuracy of 94.38%,surpassing that of a simple CNN(90.04%),ResNet18(91.72%),and ResNet50(92.48%).Finally,WM-ResNet50 was applied to monitor the whole process at laboratory tests and field cases.Both results affirmed the feasibility and effectiveness of MS inversion in predicting actual slurry diffusion ranges within deep rock layers.By comparison,it was revealed that the MS sources classified by WM-ResNet50 matched grouting records well.A solution to address insufficient diffusion under long-borehole grouting has been proposed.WM-ResNet50′s accuracy was validated through in-situ coring and XRD analysis for cement-based hydration products.This study provides a beneficial reference for similar rock signal processing and in-field grouting practices.展开更多
In complex geological environments,the analysis of drill cores to determine rock strength can be challenging due to the wide variability in the degree of fracturing,leading to subjectivity in the collection of represe...In complex geological environments,the analysis of drill cores to determine rock strength can be challenging due to the wide variability in the degree of fracturing,leading to subjectivity in the collection of representative samples for uniaxial compressive strength testing.This study evaluates non-destructive techniques on calcareous rocks with different tectonic deformations,including Equotip hardness,ultrasound P-wave velocity,thin section analysis,and calcimetry,integrated with photogrammetric fracture analysis.The investigated carbonate rock samples are sourced from drill cores derived from the Umbria-Marche fold and thrust belt(northern Apennines,Italy),including a gently dipping limb of an anticline,a hinge zone of an anticline,and a fault zone associated with a thrust.Fracture intensity,quantified by the P21 parameter using photogrammetric techniques on pre-loading rock samples,is assessed alongside macroscopic identification of discontinuities(such as stylolites,veins,and joints)using marker colours to monitor failures during uniaxial compression testing.Empirical correlations depicted by single and multi-linear relationships indicate a strong dependence between the mechanical and physical properties of limestones.Both Equotip and P-wave velocity are influenced by fracture intensity,but P-wave velocity varies significantly with discontinuity orientation,especially at 45°-90°.To refine uniaxial compressive strength predictions and mitigate multicollinearity,statistical approaches,including linear and multilinear regression,Principal Component Analysis and Gaussian Process Regression,were tested.Findings improve the reliability of non-destructive techniques for assessing rock strength in structurally complex settings,with implications for geotechnical applications.展开更多
The Jiao-Liao-Ji Belt within the North China Craton had undergone a complex tectonic evolution,marked by extensive Paleoproterozoic magmatism that produced a diverse range of mafic to felsic magmatic rocks.These event...The Jiao-Liao-Ji Belt within the North China Craton had undergone a complex tectonic evolution,marked by extensive Paleoproterozoic magmatism that produced a diverse range of mafic to felsic magmatic rocks.These events provide valuable geological records for understanding the tectonic evolution of the Jiao-Liao-Ji Belt.This study focuses on the Paleoproterozoic Chibaisong meta-gabbro in southern Jilin,investigating the source of mafic magma,petrogenesis,and tectonic setting through systematic petrological analysis,zircon U-Pb dating,and geochemical studies.The findings contribute to constraining the dynamic mechanisms of Paleoproterozoic extensional rifting in the Jiao-Liao-Ji orogenic belt.Geochemical data indicate that the samples exhibit low SiO₂(47.99–50.66 wt.%),TiO₂(0.75–3.20 wt.%),Nb(3.22–8.09 ppm),and Ta(0.22–0.51 ppm)contents,along with high TFeO₃(11.97–15.82 wt.%)and MgO(5.67–12.66 wt.%)concentrations.They also show low Nb/La ratios and high(Th/Nb)N values,consistent with the geochemical characteristics of tholeiitic basalts.The samples display low total rare earth element concentrations,weak or absent Eu anomalies,slight enrichment in light rare earth elements,relatively flat heavy rare earth element patterns,and depletion in Nb,Ta,and Ti.The meta-gabbro from southern Jilin exhibits geochemical similarities to Paleoproterozoic metamafic rocks from other regions of the Jiao-Liao-Ji Belt,resembling enriched mid-ocean ridge basalts(E-MORB)with Nb,Ta,and Ti depletion.Integration of previous studies and geochemical data suggests that the 2.16–2.10 Ga metamafic rocks in the Jiao-Liao-Ji Belt experienced contamination by older crustal material.These results indicate that the 2.16–2.10 Ga metamafic rocks are unlikely to be associated with island arc,continental arc,or mid-ocean ridge settings.Instead,they are more likely related to intraplate magmatism associated with continental rifting.展开更多
Excavation causes stress redistribution and affects the stress path during the shearing process of rock.The shear strength of rock varies under different stress paths,and the presence of defects reduces the shear stre...Excavation causes stress redistribution and affects the stress path during the shearing process of rock.The shear strength of rock varies under different stress paths,and the presence of defects reduces the shear strength.To further investigate this phenomenon,this study investigates the shear behaviour of rocks with different shear surface integrities under the influenceof different stress paths through laboratory tests and numerical simulations.The results indicate that the shear strength depends on the stress path and a decrease in the shear surface integrity reduces the degree of dependence.The cohesion and friction angle of the Mohr‒Coulomb criterion decrease with weakening of the shear surface integrity.For different stress paths,the direct shear strength is always greater than that of other shear stress paths.The pattern of changes in the acoustic emission count and cumulative count indirectly reflectsthe above findings.Numerical simulations further indicate that the different principal stress states and normal suppression effects during the shearing process lead to changes in the factors of crack propagation,resulting in different mechanical behaviours under various stress paths.For rocks with different integrity levels,the main reason for the different path dependences of shear strength is that the size of the area affected by shear is different.Shear failure will concentrate on the shear plane when the normal inhibition effect is greater.This study explores the mechanism of rock shear behaviour,providing a theoretical basis for establishing more accurate constitutive models and strength criteria.展开更多
With the growing global demand for energy,deep underground salt caverns are emerging as a potential solution for large-scale energy storage.In this study,multistage cyclic loading tests were conducted on rock salt at ...With the growing global demand for energy,deep underground salt caverns are emerging as a potential solution for large-scale energy storage.In this study,multistage cyclic loading tests were conducted on rock salt at different temperatures in combination with real-time acoustic emission(AE)monitoring.The results show that the cumulative AE count increases stepwise with increasing cyclic stress.The peak frequency is concentrated primarily in the medium-frequency range,exhibiting a band distribution across low-,medium-,and high-frequency ranges.As the temperature increases,the proportion of low-frequency signals decreases from 14.32%to 5.76%,whereas the proportion of medium-frequency signals increases from 85.48%to 94.1%.The proportion of high-frequency signals remains relatively constant between 0.1%and 0.2%.The amplitude-count relationship of the AE signals demonstrates a strong negative power-law correlation.Furthermore,with increasing temperature,the negative power-law exponent of the amplitude gradually decreases,with the b value decreasing from 1.096 to 0.837 and the a value decreasing from 7.4871 to 6.6982.Under all four temperature conditions,the dominant failure mode in rock salt is tensile cracking.However,as the temperature increases,the proportion of tensile cracks decreases from 88.59%to 75.12%,whereas the proportion of shear cracks at 80℃is nearly double that at 20℃.This finding indicates that as the temperature increases,the ductility of the material increases,and the crack propagation mode shifts from tensile to shear.This research provides valuable insights for the design and stability assessment of salt cavern reservoirs for deep underground energy storage systems.展开更多
基金Project(42077244)supported by the National Natural Science Foundation of ChinaProject(2020-05)supported by the Open Research Fund of Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization,China。
文摘Accurate prediction of rockburst intensity levels is crucial for ensuring the safety of deep hard rock engineering construction.This paper introduced an expert system for rockburst intensity level prediction that employs machine learning algorithms as the basis for its inference rules.The system comprises four modules:a database,a repository,an inference engine,and an interpreter.A database containing 1114 rockburst cases was used to construct 357 datasets that serve as the repository for the expert system.Additionally,19 types of machine learning algorithms were used to establish 6783 micro-models to construct cognitive rules within the inference engine.By integrating probability theory and marginal analysis,a fuzzy scoring method based on the SoftMax function was developed and applied to the interpreter for rockburst intensity level prediction,effectively restoring the continuity of rockburst characteristics.The research results indicate that ensemble algorithms based on decision trees are more effective in capturing the characteristics of rockburst.Key factors for accurate prediction of rockburst intensity include uniaxial compressive strength,elastic energy index,the maximum principal stress,tangential stress,and their composite indicators.The accuracy of the proposed rockburst intensity level prediction expert system was verified using 20 engineering rockburst cases,with predictions aligning closely with the actual rockburst intensity levels.
基金supported by the National Natural Science Foundation of China(Grant No.42077244)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX24_0434).
文摘To investigate the energy relief effect of real-time drilling in preventing rockburst in high-stress rock,a series of high-stress real-time drilling uniaxial compression tests were conducted on red sandstone specimens using the SG4500 drilling rig.Results showed that the mechanical behavior(i.e.peak strength and rockburst intensity)of the rock was weakened under high-stress real-time drilling and exhibited a downward trend as the drilling diameter increased.The real-time drilling energy dissipation index(ERD)was proposed to characterize the energy relief during high-stress real-time drilling.The ERD exhibited a linear increase with the real-time drilling diameter.Furthermore,the elastic strain energy of post-drilling rock showed a linear relationship with the square of stress across different stress levels,which also applied to the peak elastic strain energy and the square of peak stress.This findingreveals the intrinsic link between the weakening effect of peak elastic strain energy and peak strength due to high-stress real-time drilling,confirmingthe consistency between energy relief and pressure relief effects.By establishing relationships among rockburst proneness,peak elastic strain energy,and peak strength,it was demonstrated that high-stress real-time drilling reduces rockburst proneness through energy dissipation.Specifically,both peak elastic strain energy and rockburst proneness decreased with larger drill bit diameters,consistent with reductions in peak strength,rockburst intensity,and fractal dimensions of high-stress real-time drilled rock.These results validate the energy relief mechanism of real-time drilling in mitigating rockburst risks.
基金supported by the National Key R&D Program of China(No.2023YFC3081400)the National Natural Science Foundation of China(No.41702371)+3 种基金the Open Fund Project of State Key Laboratory of Mining Response and Disaster Prevention in Deep Coal Mines(No.SKLMRDPC22KF13)the Supported by State key Laboratory of Mining Disaster Prevention and Control(Shandong University of Science and Technology),Ministry of Education(No.DPEPM202502)the Open Fund Research Project Supported by State Key Laboratory of Strata Intelligent Control and Green Mining Co-founded by Shandong Province and the Ministry of Science and Technology(No.SICGM202503)the Fund of Chongqing Key Laboratory of Facility Damage Mechanism and Protection in Highland Mountain Environment(No.LQ24KFJJ09)。
文摘0 INTRODUCTION Due to the sudden and highly destructive nature of slope rock collapse,developing effective early warning systems has become an urgent challenge in geotechnical engineering(Cai and Detournay,2024;Loew et al.,2017).Traditional monitoring methods primarily target the acceleration stage preceding disasters(such as displacement monitoring for landslides and debris flows),which is effective for early warning of plastic collapse disasters but often inadequate for brittle failure modes(Walter et al.,2019;Chao et al.,2018;Crosta et al.,2017).
基金National Major Science and Technology Project for Deep Earth Exploration(No.2025ZD1008301)National Natural Science Foundation of China(No.52374153)for the financial supportthe support of the China Scholarship Council.
文摘Efficient hard-rock fragmentation remains a critical challenge in mechanized mining.This study designed an adjustable-spacing mold and conducted double cutting pick indentation tests on granite.Mechanical responses and fragmentation characteristics under varying horizontal stresses,pick spacings,and groove depths were systematically analyzed.Unidirectional stress concentration altered the rock fragmentation modes,exhibiting a dual effect on the fragmentation process.The maximum indentation force(F_(max)),indentation hardness index(IHI),indentation modulus(IM),and indentation energy(W)initially increased and then decreased with rising horizontal stress.Appropriate spacing promoted radial crack coalescence,whereas too small a spacing(20 mm)caused repetitive re-fragmentation of rock chips,and too large a spacing(50 mm)resulted in unbroken ridges.Pre-cut grooves weakened the rock,reducing F_(max) and specific energy(SE),thus improving fragmentation efficiency,although the improvement slowed beyond a 10-mm groove depth.Based on the results and rock-mass conditioning assisted fragmentation mechanism,a“stress-structure dual control”assisted fragmentation mechanism was proposed,and a“pre-drilling unloading−alternate stopping”mining scheme was exploratorily designed.This approach creates favorable conditions for rock fragmentation by reducing stress levels and rock mass integrity in target zones,providing theoretical support and an engineering paradigm for mecheanized mining of deep resources.
基金sponsored by the General Program of the National Natural Science Foundation of China(Grant No.42407221)the Open Fund of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Grant No.SKLGP2024K009)the Hubei Provincial Natural Science Foun-dation,China(Grant No.2023AFB567).
文摘Water storage in the Three Gorges Reservoir in China has increased the regional microseismicity.Bedding-rock landslides,one of the most common slope structures in the Three Gorges Reservoir,are highly prone to sliding under seismic loading.Existing research primarily focuses on the stability of bedding rock landslides under strong earthquakes,while studies on the cumulative damage and long-term stability of bedding rock landslides under high-frequency microseismicity remain immature.In this study,we considered bedding rock landslides under high-frequency microseismicity in the Three Gorges Reservoir area as the research subject and equivalent microseismicity as pre-peak cyclic loading.First,we analyzed the shear strength deterioration of rock mass structural planes under pre-peak cyclic loading conditions and found that the deformation and failure of structural planes involve contact and damage effects.The shear strength of the rock mass structural planes under pre-peak cyclic loading conditions is affected by the confining pressure,loading rate,loading amplitude,and number of loading cycles.Among these factors,the shear strength of the structural planes was the most sensitive to the number of loading cycles.As the number of cycles increased,the rock mass structural planes underwent three stages:stress adjustment(increase in shear strength),fatigue damage(gradual decrease in shear strength),and structural failure(rapid decrease in shear strength).The stability of bedding rock landslides under high-frequency microseismicity was analyzed,revealing that the stability of bedding rock landslides under high-frequency microseismicity can be divided into three stages:short-term enhancement,gradual degradation,and rapid deterioration,exhibiting characteristics of gradual and sudden changes.
文摘椎间盘由髓核、纤维环和软骨终板组成,对维持脊柱正常生理功能至关重要。椎间盘退变(intervertebral disc degeneration,IDD)是导致腰背痛等脊柱退行性疾病的主要病理基础,给人们的健康状况造成极大的困扰。然而目前对IDD的分子机制仍然缺乏清晰的了解,导致缺乏有效的靶向干预措施。RAS同源家族成员A(RAS homolog family member A,RhoA)/Rho相关蛋白激酶(Rho-associated protein kinase,ROCK)信号通路是调节细胞收缩、迁移和生长的经典通路。其被激活后可参与调控细胞骨架重塑、细胞外基质代谢、生物钟节律、细胞表型改变、细胞衰老及死亡等环节,进而影响IDD的病理进程。深入探究RhoA/ROCK信号通路在IDD中的作用,不仅能揭示疾病发生的分子生物学机制,也有望为研发靶向该通路的治疗策略提供理论依据。
基金supported by the National Natural Science Foundation of China(42102135,42072140,42202122 and 41790453)Science and Technology Research Program of Chongqing Municipal Education Commission(KJZD-M202101502,KJQN202201549 and KJQN202101535)+1 种基金Natural Science Foundation of Chongqing(CSTB2022NSCQ-JQX0031 and CSTB2022NSCQMSX1586)China Scholarship Council(202208505055)。
文摘1.Objective The Songliao Basin(SB)is situated on the eastern margin of Eurasia continent(Northeast Asia).During the Late Jurassic to Early Cretaceous,hundreds of rifting basins developed in this area,and the SB is a unique case among them as it evolved into the largest rift basin.The rift basin filling of SB includes Huoshiling Formation,Shahezi Formation,and Yingcheng Formation in ascending order.The mega-rifting was controlled by the Mongol-Okhotsk Collisional Belt to the north and northwest and the Pacific Subduction Zone to the east(Wang PJ et al.,2016).As the first rifting succession,the Huoshiling Formation contains key information about the formation of the rifting basins and records the evolution of the Mongol-Okhotsk Collisional Belt and the Pacific Subduction Zone.However,the geological period of the Huoshiling Formation has not been well constrained for two main reasons.First,it is easily confused with the Yingcheng Formation,as both are dominated by volcanogenic-sedimentary successions.Second,there is lack of reliable dating samples from the uppermost part of the Huoshiling Formation due to its considerable burial depth.
基金funded by the National Natural Science Foundation of China (No. 52304133)the National Key R&D Program of China (No. 2022YFC3004605)the Department of Science and Technology of Liaoning Province (No. 2023-BS-083)。
文摘Rockbursts, which mainly affect mining roadways, are dynamic disasters arising from the surrounding rock under high stress. Understanding the interaction between supports and the surrounding rock is necessary for effective rockburst control. In this study, the squeezing behavior of the surrounding rock is analyzed in rockburst roadways, and a mechanical model of rockbursts is established considering the dynamic support stress, thus deriving formulas and providing characteristic curves for describing the interaction between the support and surrounding rock. Design principles and parameters of supports for rockburst control are proposed. The results show that only when the geostress magnitude exceeds a critical value can it drive the formation of rockburst conditions. The main factors influencing the convergence response and rockburst occurrence around roadways are geostress, rock brittleness, uniaxial compressive strength, and roadway excavation size. Roadway support devices can play a role in controlling rockburst by suppressing the squeezing evolution of the surrounding rock towards instability points of rockburst. Further, the higher the strength and the longer the impact stroke of support devices with constant resistance, the more easily multiple balance points can be formed with the surrounding rock to control rockburst occurrence. Supports with long impact stroke allow adaptation to varying geostress levels around the roadway, aiding in rockburst control. The results offer a quantitative method for designing support systems for rockburst-prone roadways. The design criterion of supports is determined by the intersection between the convergence curve of the surrounding rock and the squeezing deformation curve of the support devices.
文摘Delineating sweet spots is critical for the exploration and production of oil and gas in deep and tight sand reservoirs.The lack of advanced and reliable methods makes this a challenge for geologists and geophysicists.This study introduces,for the first time,an integrated workflow that combines pre-stack seismic inversion with rock physics modeling to predict reservoir porosity and shale volume(V-shale)for sweet spot identification in tight sand reservoirs.A new elastic parameter,the density calculation index(DCI),is introduced which links acoustic and shear impedance for seismic density inversion,thereby addressing the long-standing problem of poor density inversion accuracy.A novel combined Sun–Walsh rock physics model,developed as part of this study,significantly improves V-shale evaluation from seismic data.The proposed three-step seismic inversion approach includes:(1)deriving acoustic and shear impedance from angle-stack seismic data using model-based inversion;(2)calculating density using shear impedance constrained by DCI,followed by porosity estimation from the density–porosity relation;and(3)evaluating V-shale using theα-parameter derived from the Sun–Walsh model and pre-stack inversion results.This integrated workflow provides an effective tool for building accurate 3D reservoir models,and is especially applicable to deep,low-porosity,tight sand reservoirs worldwide.
基金financial support from the National Natural Science Foundation of China(Nos.52204089,52374082)the Young Elite Scientists Sponsorship Program(No.2023QNRC001)by China Association for Science and Technology(CAST).
文摘Microseismic(MS)monitoring is an effective technique to detect mining-induced rock fractures.However,recognizing grouting-induced signals is challenging due to complex geological conditions in deep rock plates.Therefore,a hybrid model(WM-ResNet50)integrating data enhancement,a deep convolutional neural network(CNN),and convolutional block attention modules(CBAM)was proposed.Firstly,an MS system was established at the Xieqiao coal mine in Anhui Province,China.MS waveforms and injection parameters were acquired during grouting.Secondly,signals were categorized based on time-frequency characteristics to build a dataset,which was divided into training,validation,and test sets at a ratio of 4:1:1.Subsequently,the performance of WM-ResNet50 was evaluated based on indices such as individual precision,total accuracy,recall,and loss function.The results indicated that WMResNet50 achieved an average recognition accuracy of 94.38%,surpassing that of a simple CNN(90.04%),ResNet18(91.72%),and ResNet50(92.48%).Finally,WM-ResNet50 was applied to monitor the whole process at laboratory tests and field cases.Both results affirmed the feasibility and effectiveness of MS inversion in predicting actual slurry diffusion ranges within deep rock layers.By comparison,it was revealed that the MS sources classified by WM-ResNet50 matched grouting records well.A solution to address insufficient diffusion under long-borehole grouting has been proposed.WM-ResNet50′s accuracy was validated through in-situ coring and XRD analysis for cement-based hydration products.This study provides a beneficial reference for similar rock signal processing and in-field grouting practices.
文摘In complex geological environments,the analysis of drill cores to determine rock strength can be challenging due to the wide variability in the degree of fracturing,leading to subjectivity in the collection of representative samples for uniaxial compressive strength testing.This study evaluates non-destructive techniques on calcareous rocks with different tectonic deformations,including Equotip hardness,ultrasound P-wave velocity,thin section analysis,and calcimetry,integrated with photogrammetric fracture analysis.The investigated carbonate rock samples are sourced from drill cores derived from the Umbria-Marche fold and thrust belt(northern Apennines,Italy),including a gently dipping limb of an anticline,a hinge zone of an anticline,and a fault zone associated with a thrust.Fracture intensity,quantified by the P21 parameter using photogrammetric techniques on pre-loading rock samples,is assessed alongside macroscopic identification of discontinuities(such as stylolites,veins,and joints)using marker colours to monitor failures during uniaxial compression testing.Empirical correlations depicted by single and multi-linear relationships indicate a strong dependence between the mechanical and physical properties of limestones.Both Equotip and P-wave velocity are influenced by fracture intensity,but P-wave velocity varies significantly with discontinuity orientation,especially at 45°-90°.To refine uniaxial compressive strength predictions and mitigate multicollinearity,statistical approaches,including linear and multilinear regression,Principal Component Analysis and Gaussian Process Regression,were tested.Findings improve the reliability of non-destructive techniques for assessing rock strength in structurally complex settings,with implications for geotechnical applications.
基金Supported by National Natural Science Foundation of China(No.42172212).
文摘The Jiao-Liao-Ji Belt within the North China Craton had undergone a complex tectonic evolution,marked by extensive Paleoproterozoic magmatism that produced a diverse range of mafic to felsic magmatic rocks.These events provide valuable geological records for understanding the tectonic evolution of the Jiao-Liao-Ji Belt.This study focuses on the Paleoproterozoic Chibaisong meta-gabbro in southern Jilin,investigating the source of mafic magma,petrogenesis,and tectonic setting through systematic petrological analysis,zircon U-Pb dating,and geochemical studies.The findings contribute to constraining the dynamic mechanisms of Paleoproterozoic extensional rifting in the Jiao-Liao-Ji orogenic belt.Geochemical data indicate that the samples exhibit low SiO₂(47.99–50.66 wt.%),TiO₂(0.75–3.20 wt.%),Nb(3.22–8.09 ppm),and Ta(0.22–0.51 ppm)contents,along with high TFeO₃(11.97–15.82 wt.%)and MgO(5.67–12.66 wt.%)concentrations.They also show low Nb/La ratios and high(Th/Nb)N values,consistent with the geochemical characteristics of tholeiitic basalts.The samples display low total rare earth element concentrations,weak or absent Eu anomalies,slight enrichment in light rare earth elements,relatively flat heavy rare earth element patterns,and depletion in Nb,Ta,and Ti.The meta-gabbro from southern Jilin exhibits geochemical similarities to Paleoproterozoic metamafic rocks from other regions of the Jiao-Liao-Ji Belt,resembling enriched mid-ocean ridge basalts(E-MORB)with Nb,Ta,and Ti depletion.Integration of previous studies and geochemical data suggests that the 2.16–2.10 Ga metamafic rocks in the Jiao-Liao-Ji Belt experienced contamination by older crustal material.These results indicate that the 2.16–2.10 Ga metamafic rocks are unlikely to be associated with island arc,continental arc,or mid-ocean ridge settings.Instead,they are more likely related to intraplate magmatism associated with continental rifting.
基金support from the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(Grant No.KYCX24_2822)the Graduate Innovation Program of China University of Mining and Technology(Grant No.2024WLKXJ205)the National Natural Science Foundation of China(Grant No.52474157).
文摘Excavation causes stress redistribution and affects the stress path during the shearing process of rock.The shear strength of rock varies under different stress paths,and the presence of defects reduces the shear strength.To further investigate this phenomenon,this study investigates the shear behaviour of rocks with different shear surface integrities under the influenceof different stress paths through laboratory tests and numerical simulations.The results indicate that the shear strength depends on the stress path and a decrease in the shear surface integrity reduces the degree of dependence.The cohesion and friction angle of the Mohr‒Coulomb criterion decrease with weakening of the shear surface integrity.For different stress paths,the direct shear strength is always greater than that of other shear stress paths.The pattern of changes in the acoustic emission count and cumulative count indirectly reflectsthe above findings.Numerical simulations further indicate that the different principal stress states and normal suppression effects during the shearing process lead to changes in the factors of crack propagation,resulting in different mechanical behaviours under various stress paths.For rocks with different integrity levels,the main reason for the different path dependences of shear strength is that the size of the area affected by shear is different.Shear failure will concentrate on the shear plane when the normal inhibition effect is greater.This study explores the mechanism of rock shear behaviour,providing a theoretical basis for establishing more accurate constitutive models and strength criteria.
基金supported by the Major Research Development Program of Hubei Province,China(Grant Nos.2022BAA093 and 2022BAD163)the Open Research Fund of the State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(Grant No.SKLGME023008).
文摘With the growing global demand for energy,deep underground salt caverns are emerging as a potential solution for large-scale energy storage.In this study,multistage cyclic loading tests were conducted on rock salt at different temperatures in combination with real-time acoustic emission(AE)monitoring.The results show that the cumulative AE count increases stepwise with increasing cyclic stress.The peak frequency is concentrated primarily in the medium-frequency range,exhibiting a band distribution across low-,medium-,and high-frequency ranges.As the temperature increases,the proportion of low-frequency signals decreases from 14.32%to 5.76%,whereas the proportion of medium-frequency signals increases from 85.48%to 94.1%.The proportion of high-frequency signals remains relatively constant between 0.1%and 0.2%.The amplitude-count relationship of the AE signals demonstrates a strong negative power-law correlation.Furthermore,with increasing temperature,the negative power-law exponent of the amplitude gradually decreases,with the b value decreasing from 1.096 to 0.837 and the a value decreasing from 7.4871 to 6.6982.Under all four temperature conditions,the dominant failure mode in rock salt is tensile cracking.However,as the temperature increases,the proportion of tensile cracks decreases from 88.59%to 75.12%,whereas the proportion of shear cracks at 80℃is nearly double that at 20℃.This finding indicates that as the temperature increases,the ductility of the material increases,and the crack propagation mode shifts from tensile to shear.This research provides valuable insights for the design and stability assessment of salt cavern reservoirs for deep underground energy storage systems.
