Knowledge of the seismogenic environment of fault zones is critical for understanding the processes and mechanisms of large earthquakes.We conducted a rock magnetic study of the fault rocks and protoliths to investiga...Knowledge of the seismogenic environment of fault zones is critical for understanding the processes and mechanisms of large earthquakes.We conducted a rock magnetic study of the fault rocks and protoliths to investigate the seismogenic environment of earthquakes in the Motuo fault zone,in the eastern Himalayan syntaxis.The results indicate that magnetite is the principal magnetic carrier in the fault rocks and protolith,while the protolith has a higher content of paramagnetic minerals than the fault rocks.The fault rocks are characterized by a high magnetic susceptibility relative to the protolith in the Motuo fault zone.This is likely due to the thermal alteration of paramagnetic minerals to magnetite caused by coseismic frictional heating with concomitant hydrothermal fluid circulation.The high magnetic susceptibility of the fault rocks and neoformed magnetite indicate that large earthquakes with frictional heating temperatures>500℃have occurred in the Motuo fault zone in the past,and that the fault maintained an oxidizing environment with weak fluid action during these earthquakes.Our results reveal the seismogenic environment of the Motuo fault zone,and they are potentially important for the evaluation of the regional stability in the eastern Himalayan syntaxis.展开更多
The structures of the mantle transition zone(MTZ)are of great significance for studying interactions of the subducted slab and deep mantle and related slab dynamics beneath subduction zones.Here by dense near-source S...The structures of the mantle transition zone(MTZ)are of great significance for studying interactions of the subducted slab and deep mantle and related slab dynamics beneath subduction zones.Here by dense near-source SdP sampling from a large global dataset,we image topographies of transition zone discontinuities such as the 410-km and 660-km discontinuities(410 and 660)beneath the Kamchatka and conduct cross-section comparisons with the seismicity.Compared with the IASP91 model,the 410 exhibits apparent uplifts of 45-65 km with an average of 55 km in a horizontal width of~130 km,corresponding to lowtemperature anomalies of 750-1083 K with an average of 916 K.In contrast,the 660 shows depressions of 15-37 km with an average of 25 km together with downward deflections in a width of~260 km,implying low-temperature anomalies of 161-397 K with an average of 268 K.Thus,we confirm a thickened MTZ with a thickness of 325-345 km around the cold descending Pacific slab.We suggest that topographic patterns of transition zone discontinuities imply a Pacific slab that has been significantly heated in the MTZ with broadened thermal effects on the 660.When considered along with other studies,we infer that the slab is possibly heated by hot mantle flows around the torn slab window extended to at least the MTZ range,thus inducing variations in thermal and rheological properties of the slab.Our seismic results can provide more insight into slab dynamics in the northwestern Pacific.展开更多
The Yishu fault zone in Shandong Province,China,exhibits favorable conditions for medium-and high-temperature geothermal storage.However,its geothermal occurrence patterns and heat storage model remain unclear.Recogni...The Yishu fault zone in Shandong Province,China,exhibits favorable conditions for medium-and high-temperature geothermal storage.However,its geothermal occurrence patterns and heat storage model remain unclear.Recognizing the importance of deep heat sources and heat channels in unraveling the formation mechanisms of medium-and high-temperature geothermal systems,we conducted a magnetotelluric survey along the Yishu fault zone,which contained 10 survey lines and 119 usable points.Using two-dimensional and three-dimensional nonlinear conjugate gradient inversion,the deep electrical structure was obtained,and the three-dimensional geothermal reservoir model in the study area was constructed for the first time.The results show that the deep low-resistance anomaly in the Yishu fault zone moves upward through the channel with slightly higher resistivity,forming a relatively low-resistance layer and a low-resistance layer in the shallow part,corresponding to the heat source,thermal conduction fault,heat reservoir,and overburden layer,respectively.The fault structure primarily controls regional geothermal anomalies,influencing atmospheric precipitation,surface water infiltration,and geothermal water migration pathways.The results of this study have a certain guiding significance for the study of the formation mechanism and distribution law of geothermal resources in the middle and deep strata of the Yishu fault zone.Additionally,the results provide valuable insights for the exploration and assessment of geothermal resources in the area.展开更多
The temperature prediction of the Clamp-conductor coupling zone plays a crucial role in ensuring the safe and stable operation of overhead transmission lines and optimizing the thermal stability margin of transmission...The temperature prediction of the Clamp-conductor coupling zone plays a crucial role in ensuring the safe and stable operation of overhead transmission lines and optimizing the thermal stability margin of transmission lines.While existing research in this field has thoroughly explored temperature rise prediction,the focus has been relatively narrow,either targeting conductors exclusively or focusing solely on clamps,with little attention given to the temperature rise in the conductor-clampcoupling zoneor the influenceof clamp temperatureonconductor temperature rise.Based on this,considering axial heat transfer between the clamp and the conductor,this study develops a thermal model to calculate temperature in the clamp-conductor interface zone.A Whale Optimization Algorithm(WOA)-based parameter identification method is employed to overcome challenges in determining model parameters.To validate model performance,a current-carrying temperature-rise experimental platform was designed to supply data for both model verification and parameter identification.By comparing the calculation results with the experimental data,the results show that the maximum average error does not exceed 1.4%,and the maximum error is only 2.79%,verifying the validity of the parameter identificationmethod and thermalmodel.Thiswork lays a theoretical foundation for predicting temperature distributions at clamp-conductor interfaces under realistic meteorological conditions and supports short-termdynamic capacity increases for overhead conductors,demonstrating significant practical relevance.展开更多
Austenitic stainless steels are usually chosen to make many components of nuclear power plants （NPPs）. However, their microstructure in the heat-affected zone （HAZ） will change during the welding process. Some fai...Austenitic stainless steels are usually chosen to make many components of nuclear power plants （NPPs）. However, their microstructure in the heat-affected zone （HAZ） will change during the welding process. Some failures of the weld joints, mainly stress corrosion cracking （SCC）, have been found to be located in the HAZ. In this research, the microstructure, micro-hardness, residual strain and SCC behavior at different locations of the 316L HAZ cut from a safeend dissimilar metal weld joint were studied. However, traditional optical microscope observation could not find any microstructural difference between the HAZ and the base metal, higher residual strain and micro-hardness, and higher fraction of random high-angle grain boundaries were found in the HAZ than in the base metal when studied by using electron back-scattering diffraction scanning and micro-hardness test. What＇s more, the residual strain, the microhardness and the fraction of random grain boundaries decreased, while the fraction of coincidence site lattice grain boundaries increased with increasing the distance from the fusion boundary in 316L HAZ. Creviced bent beam test was applied to evaluate the SCC susceptibility at different locations of 316L HAZ and base metal. It was found that the HAZ had higher SCC susceptibility than the base metal and SCC resistance increased when increasing the distance from the fusion boundary in 316L HAZ.展开更多
基金supported by the Fundamental Research Funds of the Institute of Geomechanics(DZLXJK202401)the National Natural Science Foundation of China(42177172,U2244226,42172255)+1 种基金the China Geological Survey Project(DD20230538)Deep Earth Probe and Mineral Resources ExplorationNational Science and Technology Major Project(2024ZD1000500)。
文摘Knowledge of the seismogenic environment of fault zones is critical for understanding the processes and mechanisms of large earthquakes.We conducted a rock magnetic study of the fault rocks and protoliths to investigate the seismogenic environment of earthquakes in the Motuo fault zone,in the eastern Himalayan syntaxis.The results indicate that magnetite is the principal magnetic carrier in the fault rocks and protolith,while the protolith has a higher content of paramagnetic minerals than the fault rocks.The fault rocks are characterized by a high magnetic susceptibility relative to the protolith in the Motuo fault zone.This is likely due to the thermal alteration of paramagnetic minerals to magnetite caused by coseismic frictional heating with concomitant hydrothermal fluid circulation.The high magnetic susceptibility of the fault rocks and neoformed magnetite indicate that large earthquakes with frictional heating temperatures>500℃have occurred in the Motuo fault zone in the past,and that the fault maintained an oxidizing environment with weak fluid action during these earthquakes.Our results reveal the seismogenic environment of the Motuo fault zone,and they are potentially important for the evaluation of the regional stability in the eastern Himalayan syntaxis.
基金supported by the Central Public-interest Scientific Institution Basal Research Fund(No.CEAIEF 20220201)the National Natural Science Foundation of China(Nos.42374113 and 42074101)the Central Publicinterest Scientific Institution Basal Research Fund(No.CEAIEF20230204).
文摘The structures of the mantle transition zone(MTZ)are of great significance for studying interactions of the subducted slab and deep mantle and related slab dynamics beneath subduction zones.Here by dense near-source SdP sampling from a large global dataset,we image topographies of transition zone discontinuities such as the 410-km and 660-km discontinuities(410 and 660)beneath the Kamchatka and conduct cross-section comparisons with the seismicity.Compared with the IASP91 model,the 410 exhibits apparent uplifts of 45-65 km with an average of 55 km in a horizontal width of~130 km,corresponding to lowtemperature anomalies of 750-1083 K with an average of 916 K.In contrast,the 660 shows depressions of 15-37 km with an average of 25 km together with downward deflections in a width of~260 km,implying low-temperature anomalies of 161-397 K with an average of 268 K.Thus,we confirm a thickened MTZ with a thickness of 325-345 km around the cold descending Pacific slab.We suggest that topographic patterns of transition zone discontinuities imply a Pacific slab that has been significantly heated in the MTZ with broadened thermal effects on the 660.When considered along with other studies,we infer that the slab is possibly heated by hot mantle flows around the torn slab window extended to at least the MTZ range,thus inducing variations in thermal and rheological properties of the slab.Our seismic results can provide more insight into slab dynamics in the northwestern Pacific.
文摘The Yishu fault zone in Shandong Province,China,exhibits favorable conditions for medium-and high-temperature geothermal storage.However,its geothermal occurrence patterns and heat storage model remain unclear.Recognizing the importance of deep heat sources and heat channels in unraveling the formation mechanisms of medium-and high-temperature geothermal systems,we conducted a magnetotelluric survey along the Yishu fault zone,which contained 10 survey lines and 119 usable points.Using two-dimensional and three-dimensional nonlinear conjugate gradient inversion,the deep electrical structure was obtained,and the three-dimensional geothermal reservoir model in the study area was constructed for the first time.The results show that the deep low-resistance anomaly in the Yishu fault zone moves upward through the channel with slightly higher resistivity,forming a relatively low-resistance layer and a low-resistance layer in the shallow part,corresponding to the heat source,thermal conduction fault,heat reservoir,and overburden layer,respectively.The fault structure primarily controls regional geothermal anomalies,influencing atmospheric precipitation,surface water infiltration,and geothermal water migration pathways.The results of this study have a certain guiding significance for the study of the formation mechanism and distribution law of geothermal resources in the middle and deep strata of the Yishu fault zone.Additionally,the results provide valuable insights for the exploration and assessment of geothermal resources in the area.
基金supported by the Technology Innovation Leading Program of Shaanxi(2024QCY-KXJ-009)the Research Plan of the EducationDepartment of Shaanxi Province(23JC028)+1 种基金supported by the National Key Laboratory of Metal Forming Technology and Heavy Equipment B2408100.W14.Key Research and Development Program of Shaanxi(2025CY-YBXM-489).
文摘The temperature prediction of the Clamp-conductor coupling zone plays a crucial role in ensuring the safe and stable operation of overhead transmission lines and optimizing the thermal stability margin of transmission lines.While existing research in this field has thoroughly explored temperature rise prediction,the focus has been relatively narrow,either targeting conductors exclusively or focusing solely on clamps,with little attention given to the temperature rise in the conductor-clampcoupling zoneor the influenceof clamp temperatureonconductor temperature rise.Based on this,considering axial heat transfer between the clamp and the conductor,this study develops a thermal model to calculate temperature in the clamp-conductor interface zone.A Whale Optimization Algorithm(WOA)-based parameter identification method is employed to overcome challenges in determining model parameters.To validate model performance,a current-carrying temperature-rise experimental platform was designed to supply data for both model verification and parameter identification.By comparing the calculation results with the experimental data,the results show that the maximum average error does not exceed 1.4%,and the maximum error is only 2.79%,verifying the validity of the parameter identificationmethod and thermalmodel.Thiswork lays a theoretical foundation for predicting temperature distributions at clamp-conductor interfaces under realistic meteorological conditions and supports short-termdynamic capacity increases for overhead conductors,demonstrating significant practical relevance.
基金financially supported by the National Natural Science Foundation of China (No. 51301183)Science and Technology Commission of Shanghai Municipality under Grant No. 14DZ2250300, Shanghai, China
文摘Austenitic stainless steels are usually chosen to make many components of nuclear power plants （NPPs）. However, their microstructure in the heat-affected zone （HAZ） will change during the welding process. Some failures of the weld joints, mainly stress corrosion cracking （SCC）, have been found to be located in the HAZ. In this research, the microstructure, micro-hardness, residual strain and SCC behavior at different locations of the 316L HAZ cut from a safeend dissimilar metal weld joint were studied. However, traditional optical microscope observation could not find any microstructural difference between the HAZ and the base metal, higher residual strain and micro-hardness, and higher fraction of random high-angle grain boundaries were found in the HAZ than in the base metal when studied by using electron back-scattering diffraction scanning and micro-hardness test. What＇s more, the residual strain, the microhardness and the fraction of random grain boundaries decreased, while the fraction of coincidence site lattice grain boundaries increased with increasing the distance from the fusion boundary in 316L HAZ. Creviced bent beam test was applied to evaluate the SCC susceptibility at different locations of 316L HAZ and base metal. It was found that the HAZ had higher SCC susceptibility than the base metal and SCC resistance increased when increasing the distance from the fusion boundary in 316L HAZ.
