Basement structures may influence how ruptures propagate during an earthquake.However,most structural evidence is beneath the thick layer of younger volcanic sediments.In this study,gravity method was applied to disco...Basement structures may influence how ruptures propagate during an earthquake.However,most structural evidence is beneath the thick layer of younger volcanic sediments.In this study,gravity method was applied to discover more features of the basement structure.A land survey of gravity measurement was conducted at 383 stations south of Toba.The observed gravity was then used to generate Complete Bouguer Anomaly and residual-regional anomaly maps.In addition,several edge enhancements based on derivations were applied.All results presented lineations that could be linked to previously recognized active faults and structures.Additionally,the most prominent feature is a large northwest-southeast elongated high anomaly,almost sub-parallel to the Sumatra Fault Zone(SFZ).Since the feature is also located at the continuation of the Medial Sumatra Tectonic Zone(MSTZ),the body might be the hidden part of this major tectonic zone.The occurrence of MSTZ across the SFZ would affect the rupture propagation of earthquake events in the fault segment of the SFZ.展开更多
Crack control of basement roof slab is a key technical challenge to ensure building safety and durability.Based on the requirements of“General Specification for Concrete Structures”(GB55008-2021),this paper systemat...Crack control of basement roof slab is a key technical challenge to ensure building safety and durability.Based on the requirements of“General Specification for Concrete Structures”(GB55008-2021),this paper systematically analyses the causes of cracks,and puts forward a whole-process prevention and control system covering design optimization,low-shrinkage material proportioning,fine control of construction technology,and dynamic monitoring and repair.Through structural finite element simulation,wireless sensor network real-time monitoring,and carbon fibre fabric reinforcement test,the effectiveness of the multi-technology synergistic control framework is verified,and the engineering cases show that the crack width after repair is stable within 0.1mm,and the bearing capacity is increased by more than 30%.The study provides theoretical support for crack prevention and control in super-long underground projects,and looks forward to the direction of integration application of BIM technology and intelligent materials.展开更多
This study integrates gravity and aeromagnetic datasets to delineate basement depth and characterise the subsurface structural framework of the Gerad Graben in the western Sirt Basin,Libya.Techniques including high-pa...This study integrates gravity and aeromagnetic datasets to delineate basement depth and characterise the subsurface structural framework of the Gerad Graben in the western Sirt Basin,Libya.Techniques including high-pass filtering,Centre for Exploration Targeting(CET) edge detection,Source Parameter Imaging(SPI),and Euler Deconvolution(ED) were applied to residual gravity and residual reduced-topole(RTP) magnetic data to enhance fault mapping and basement morphology.Tests of various cutoff wavelengths show that 10 km for gravity and 15 km for magnetic data provide optimal resolution of shallow structures while preserving deeper trends.Forward 2D GM-SYS modelling and Werner Deconvolution further constrained the geometry and depth of intrusive bodies and fault systems.Results reveal a structurally complex graben with NE-SW,NW-SE,ENE-WSW,and N-S trending faults,indicating multiphase tectonic deformation.Graben-bounding faults show displacement values of600-4290 m,and basement depths in the central depocenter reach 4275-4300 m,validated by well NTF-50.Magnetic anomalies indicate intrusive igneous bodies,including NW-SE-trending sills and dikes,associated with the Tibesti and Al Haruj volcanic provinces.These intrusions likely caused localised heating,uplift,and fault reactivation.The integrated interpretation supports a tectonomagmatic evolution involving successive rifting phases from the Paleozoic to Cenozoic,influenced by inherited Precambrian structures.These features,coupled with substantial sediment infill and magmatic activity,enhance the hydrocarbon potential of the Gerad Graben,suggesting the presence of structural and stratigraphic traps within the broader of Sirt Basin petroleum system.展开更多
The basement was located at the bottom of the building,which not only affected the quality of the whole construction project but also had special requirements for construction technology and construction requirements....The basement was located at the bottom of the building,which not only affected the quality of the whole construction project but also had special requirements for construction technology and construction requirements.In modern times,with the increasing height of the building,the pressure on the ground has grown,and the demands for basements in construction projects have also steadily increased.With the development of modern technology,various construction techniques for basements emerged within the construction industry.Thus,this paper analyses the type of basement floor construction technologies,highlighting the application of these methods,and points out critical issues to consider.By examining frequent basement leakage problems,the paper proposed several measures to improve the quality if basement construction,aiming to better protect the service life of the building and further improve overall quality,and offering valuable insights for future projects.展开更多
With the rapid development of heavy haul railway transportation technology,tunnel foundation defects and their effects on structural performance have attracted wide attention.This paper systematically investigates the...With the rapid development of heavy haul railway transportation technology,tunnel foundation defects and their effects on structural performance have attracted wide attention.This paper systematically investigates the evolution mechanism of tun-nel foundation defects in heavy haul railway tunnels and their impact on structural stiffness degradation through experiments and numerical simulations.A heavy haul train-ballasted track-tunnel basement-surround rock dynamic interaction model(TTTR model)is constructed.Firstly,the study reveals the four-stage evolution process of initial defects in the tunnel base-ment under complex environmental conditions.Experiments were conducted to measure the load-bearing capacity and stiff-ness degradation of the tunnel basement structure under different defect states.It is found that foundation defects,especially under the coupling of loose fill in the basement with the water-rich environment of the surrounding rock,significantly reduce the stiffness of the tunnel bottom structure and increase the risk of structural damage.Then,based on refined simulation of wheel-rail interaction and multi-scale coupled modeling technology,the TTTR dynamic interaction model was successfully constructed,and its validity was proven through numerical validation.A time-varying coupling technique of constrained boundary substructures(CBS technique)was adopted,significantly improving computational efficiency while ensuring calculation accuracy.The study also analyzes the effects of different degrees of void defects on the dynamic behavior of the train and the dynamic characteristics of the tunnel structure.It finds that foundation defects have a significant impact on the train’s operational state,track vibration displacement,and vibration stress of the tunnel lining structure,especially under the coupling effect of basement voids and the water-rich environment,which has the greatest impact.The research results of this paper provide a theoretical basis and technical support for the maintenance and reinforcement of tunnel foundation structures.展开更多
Based on the data of seismic reflection, seismic refraction and magnetism collected in the research area and geology obtained from adjacent areas, this paper deals with the issue of basement constitution of the southe...Based on the data of seismic reflection, seismic refraction and magnetism collected in the research area and geology obtained from adjacent areas, this paper deals with the issue of basement constitution of the southern part of the Okinawa Trough. In the shelf basin of the East China Sea, Taiwan folded belt and Ryukyu Islands folded belt which surround the trough, outcrop Later Paleozoic, Mesozoic and Eogene strata. In the southern trough, multichannel seismic reflection data indicate that the overlying strata are composed of Neogene and Quaternary deposits, and the acoustic basement consists of Eogent and even older strata. Seismic refraction profiles show that there are Eogene and Mesozoic velocity layers with longitudinal velocities of 4.7 - 5.3 km/s and 6.3 km/s respectively beneath the Quaternary-Miocene Layers. Qualitative analysis and forward and reversed calculation of magnetic data show that the magnetic basement is mainly formed by metamorphic rocks, the Yanshanian neutral-acid magmatic rocks and the Himalayan neutral-basic magmatic rocks being the next components, and the magnetic basement is mostly corresponding to the acoustic basement. Comprehensive analyses demonstrate that the basement of the southern Okinawa Trough is mainly formed by Eogene system and Mesozoic and Upper Paleozoic groups metamorphosed in varying degrees, and the basic magmatic rocks of Himalayan epoch have been formed in some parts of the basin.展开更多
The Prydz Bay-Prince Charles Mountains region in East Antarctica constitutes an exceptional geological transect for investigating continental evolution from the Archean to the Phanerozoic and its relationship with sup...The Prydz Bay-Prince Charles Mountains region in East Antarctica constitutes an exceptional geological transect for investigating continental evolution from the Archean to the Phanerozoic and its relationship with supercontinent cycles.This region preserves a complex record of magmatism,metamorphism,and tectonic reworking.Studies by the Chinese National Antarctic Research Expeditions in this region have yielded critical insights into the geological evolution of Antarctica.Key advances over the past decades encompass the elucidation of the Pan-African and Grenvillian tectono-metamorphic history,the delineation of the continent’s crustal and lithospheric architecture,and the identification of extensive ultrahigh-temperature metamorphism and rare mineral assemblages.Despite these advances,many fundamental questions remain unresolved.The spatial and temporal extents of ancient orogenesis are poorly constrained across different crustal blocks,and the tectonic drivers of extreme metamorphism continue to be debated.The role of deep lithospheric architecture in controlling both past orogenic processes and present-day glacial isostatic adjustment remains underexplored.Furthermore,the origins of ancient cratonic nuclei and their constraints on early Earth geodynamics warrant further investigation.Future research should prioritize integrated,multi-disciplinary approaches that combine geological and geophysical analyses.Key objectives include delineating the architecture and evolution of subglacial basement,reconstructing the Phanerozoic uplift and erosion history of the orogens,and evaluating feedback mechanisms among lithospheric evolution,ice-sheet dynamics,and long-term climate.Holistic cross-disciplinary investigations will be essential to unravel the connections between deep Earth processes and surface systems in one of the planet’s most enigmatic and geologically significant regions.展开更多
1.Objective Nigeria lies between the West African Craton and the Congo Craton,south of the Tuareg Shield(Ogunmola JK et al.,2015).The Nasarawa pegmatite field mainly comprises of the Precambrian Basement Complex(inclu...1.Objective Nigeria lies between the West African Craton and the Congo Craton,south of the Tuareg Shield(Ogunmola JK et al.,2015).The Nasarawa pegmatite field mainly comprises of the Precambrian Basement Complex(including Archean-Proterozoic migmatite,gneiss,schists and Pan-African “Older Granites”),Mesozoic alkaline ring complexes(“Younger Granites”) and sedimentary basins(Yang QD et al.,2023;Fig.1a).“Older Granites” are part of the Pan-African mobile belt;“Younger Granites” has significant peralkaline characteristics.“Younger Granites” has a wide distribution in the north-central region of Nigeria,including areas such as Kano,Jos-Bauchi,Mada,and Nasarawa,and the emplacement age gradually decreases from north to south from 213 Ma(Dutse complex) to 141 Ma(Afu complex)(Amuda AK et al.,2021).展开更多
基金National Research and Innovation Agency(BRIN),Indonesia,with Grant No.373/II/FR/3/2022(Expedition and Exploration Fund)and 676/III/PR.01.December 03,2021(Geological Hazard In-House Program)。
文摘Basement structures may influence how ruptures propagate during an earthquake.However,most structural evidence is beneath the thick layer of younger volcanic sediments.In this study,gravity method was applied to discover more features of the basement structure.A land survey of gravity measurement was conducted at 383 stations south of Toba.The observed gravity was then used to generate Complete Bouguer Anomaly and residual-regional anomaly maps.In addition,several edge enhancements based on derivations were applied.All results presented lineations that could be linked to previously recognized active faults and structures.Additionally,the most prominent feature is a large northwest-southeast elongated high anomaly,almost sub-parallel to the Sumatra Fault Zone(SFZ).Since the feature is also located at the continuation of the Medial Sumatra Tectonic Zone(MSTZ),the body might be the hidden part of this major tectonic zone.The occurrence of MSTZ across the SFZ would affect the rupture propagation of earthquake events in the fault segment of the SFZ.
文摘Crack control of basement roof slab is a key technical challenge to ensure building safety and durability.Based on the requirements of“General Specification for Concrete Structures”(GB55008-2021),this paper systematically analyses the causes of cracks,and puts forward a whole-process prevention and control system covering design optimization,low-shrinkage material proportioning,fine control of construction technology,and dynamic monitoring and repair.Through structural finite element simulation,wireless sensor network real-time monitoring,and carbon fibre fabric reinforcement test,the effectiveness of the multi-technology synergistic control framework is verified,and the engineering cases show that the crack width after repair is stable within 0.1mm,and the bearing capacity is increased by more than 30%.The study provides theoretical support for crack prevention and control in super-long underground projects,and looks forward to the direction of integration application of BIM technology and intelligent materials.
文摘This study integrates gravity and aeromagnetic datasets to delineate basement depth and characterise the subsurface structural framework of the Gerad Graben in the western Sirt Basin,Libya.Techniques including high-pass filtering,Centre for Exploration Targeting(CET) edge detection,Source Parameter Imaging(SPI),and Euler Deconvolution(ED) were applied to residual gravity and residual reduced-topole(RTP) magnetic data to enhance fault mapping and basement morphology.Tests of various cutoff wavelengths show that 10 km for gravity and 15 km for magnetic data provide optimal resolution of shallow structures while preserving deeper trends.Forward 2D GM-SYS modelling and Werner Deconvolution further constrained the geometry and depth of intrusive bodies and fault systems.Results reveal a structurally complex graben with NE-SW,NW-SE,ENE-WSW,and N-S trending faults,indicating multiphase tectonic deformation.Graben-bounding faults show displacement values of600-4290 m,and basement depths in the central depocenter reach 4275-4300 m,validated by well NTF-50.Magnetic anomalies indicate intrusive igneous bodies,including NW-SE-trending sills and dikes,associated with the Tibesti and Al Haruj volcanic provinces.These intrusions likely caused localised heating,uplift,and fault reactivation.The integrated interpretation supports a tectonomagmatic evolution involving successive rifting phases from the Paleozoic to Cenozoic,influenced by inherited Precambrian structures.These features,coupled with substantial sediment infill and magmatic activity,enhance the hydrocarbon potential of the Gerad Graben,suggesting the presence of structural and stratigraphic traps within the broader of Sirt Basin petroleum system.
文摘The basement was located at the bottom of the building,which not only affected the quality of the whole construction project but also had special requirements for construction technology and construction requirements.In modern times,with the increasing height of the building,the pressure on the ground has grown,and the demands for basements in construction projects have also steadily increased.With the development of modern technology,various construction techniques for basements emerged within the construction industry.Thus,this paper analyses the type of basement floor construction technologies,highlighting the application of these methods,and points out critical issues to consider.By examining frequent basement leakage problems,the paper proposed several measures to improve the quality if basement construction,aiming to better protect the service life of the building and further improve overall quality,and offering valuable insights for future projects.
基金funded by the National Natural Science Foundation of China (Grant No. 52178402 & 52378468)the Open Foundation of MOE Key Laboratory of Engineering Structures of Heavy Haul Railway (Central South University) (Grant No. 2022JZZ01)+1 种基金the National Engineering Research Center for High-Speed Railway Construction Technology for their project supportthe support from the MOE Key Laboratory of Engineering Structure of Heavy Haul Railway (Central South University)
文摘With the rapid development of heavy haul railway transportation technology,tunnel foundation defects and their effects on structural performance have attracted wide attention.This paper systematically investigates the evolution mechanism of tun-nel foundation defects in heavy haul railway tunnels and their impact on structural stiffness degradation through experiments and numerical simulations.A heavy haul train-ballasted track-tunnel basement-surround rock dynamic interaction model(TTTR model)is constructed.Firstly,the study reveals the four-stage evolution process of initial defects in the tunnel base-ment under complex environmental conditions.Experiments were conducted to measure the load-bearing capacity and stiff-ness degradation of the tunnel basement structure under different defect states.It is found that foundation defects,especially under the coupling of loose fill in the basement with the water-rich environment of the surrounding rock,significantly reduce the stiffness of the tunnel bottom structure and increase the risk of structural damage.Then,based on refined simulation of wheel-rail interaction and multi-scale coupled modeling technology,the TTTR dynamic interaction model was successfully constructed,and its validity was proven through numerical validation.A time-varying coupling technique of constrained boundary substructures(CBS technique)was adopted,significantly improving computational efficiency while ensuring calculation accuracy.The study also analyzes the effects of different degrees of void defects on the dynamic behavior of the train and the dynamic characteristics of the tunnel structure.It finds that foundation defects have a significant impact on the train’s operational state,track vibration displacement,and vibration stress of the tunnel lining structure,especially under the coupling effect of basement voids and the water-rich environment,which has the greatest impact.The research results of this paper provide a theoretical basis and technical support for the maintenance and reinforcement of tunnel foundation structures.
文摘Based on the data of seismic reflection, seismic refraction and magnetism collected in the research area and geology obtained from adjacent areas, this paper deals with the issue of basement constitution of the southern part of the Okinawa Trough. In the shelf basin of the East China Sea, Taiwan folded belt and Ryukyu Islands folded belt which surround the trough, outcrop Later Paleozoic, Mesozoic and Eogene strata. In the southern trough, multichannel seismic reflection data indicate that the overlying strata are composed of Neogene and Quaternary deposits, and the acoustic basement consists of Eogent and even older strata. Seismic refraction profiles show that there are Eogene and Mesozoic velocity layers with longitudinal velocities of 4.7 - 5.3 km/s and 6.3 km/s respectively beneath the Quaternary-Miocene Layers. Qualitative analysis and forward and reversed calculation of magnetic data show that the magnetic basement is mainly formed by metamorphic rocks, the Yanshanian neutral-acid magmatic rocks and the Himalayan neutral-basic magmatic rocks being the next components, and the magnetic basement is mostly corresponding to the acoustic basement. Comprehensive analyses demonstrate that the basement of the southern Okinawa Trough is mainly formed by Eogene system and Mesozoic and Upper Paleozoic groups metamorphosed in varying degrees, and the basic magmatic rocks of Himalayan epoch have been formed in some parts of the basin.
基金financially supported by the National Natural Science Foundation of China(Grant nos.U2444210,42172068)the Fundamental Research Funds of the Chinese Academy of Geological Sciences(CAGS)(Grant no.JKYZD202321)geological survey program(Grant no.DD20221810).
文摘The Prydz Bay-Prince Charles Mountains region in East Antarctica constitutes an exceptional geological transect for investigating continental evolution from the Archean to the Phanerozoic and its relationship with supercontinent cycles.This region preserves a complex record of magmatism,metamorphism,and tectonic reworking.Studies by the Chinese National Antarctic Research Expeditions in this region have yielded critical insights into the geological evolution of Antarctica.Key advances over the past decades encompass the elucidation of the Pan-African and Grenvillian tectono-metamorphic history,the delineation of the continent’s crustal and lithospheric architecture,and the identification of extensive ultrahigh-temperature metamorphism and rare mineral assemblages.Despite these advances,many fundamental questions remain unresolved.The spatial and temporal extents of ancient orogenesis are poorly constrained across different crustal blocks,and the tectonic drivers of extreme metamorphism continue to be debated.The role of deep lithospheric architecture in controlling both past orogenic processes and present-day glacial isostatic adjustment remains underexplored.Furthermore,the origins of ancient cratonic nuclei and their constraints on early Earth geodynamics warrant further investigation.Future research should prioritize integrated,multi-disciplinary approaches that combine geological and geophysical analyses.Key objectives include delineating the architecture and evolution of subglacial basement,reconstructing the Phanerozoic uplift and erosion history of the orogens,and evaluating feedback mechanisms among lithospheric evolution,ice-sheet dynamics,and long-term climate.Holistic cross-disciplinary investigations will be essential to unravel the connections between deep Earth processes and surface systems in one of the planet’s most enigmatic and geologically significant regions.
基金funded by the projects of Tianjin North China Geological Exploration Bureau (HK2023–B01,HK2022–B08)China Geological Survey (DD20230576,DD20201152)。
文摘1.Objective Nigeria lies between the West African Craton and the Congo Craton,south of the Tuareg Shield(Ogunmola JK et al.,2015).The Nasarawa pegmatite field mainly comprises of the Precambrian Basement Complex(including Archean-Proterozoic migmatite,gneiss,schists and Pan-African “Older Granites”),Mesozoic alkaline ring complexes(“Younger Granites”) and sedimentary basins(Yang QD et al.,2023;Fig.1a).“Older Granites” are part of the Pan-African mobile belt;“Younger Granites” has significant peralkaline characteristics.“Younger Granites” has a wide distribution in the north-central region of Nigeria,including areas such as Kano,Jos-Bauchi,Mada,and Nasarawa,and the emplacement age gradually decreases from north to south from 213 Ma(Dutse complex) to 141 Ma(Afu complex)(Amuda AK et al.,2021).
