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Fragility analysis of canyon-crossing bridges considering the near-source canyon topographic effect 认领 引用
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作者 WANG Ming-dong LU Kai-wei +3 位作者 LI Shuai WANG Jing-quan HU Yu-qing ZHANG Ning 《Journal of Central South University》 SCIE EI CAS CSCD 2026年第4期1687-1705,共19页
Previous earthquakes indicate that near-source canyon topographic effect(NCTE)can substantially amplify the seismic responses of canyon-crossing bridges(CCBs).While the conventional practices are to make disaster resp... Previous earthquakes indicate that near-source canyon topographic effect(NCTE)can substantially amplify the seismic responses of canyon-crossing bridges(CCBs).While the conventional practices are to make disaster response decisions based on the deterministic approaches,they cannot provide a holistic view regarding the impacts of uncertainties of ground motions on CCBs.Thus,this study adopts the performance-based seismic assessment in a probabilistic framework to evaluate the seismic fragility of CCBs considering NCTE.For this purpose,a numerical model of a typical tall-pier CCB across a V-shaped canyon is constructed using OpenSees.Eighteen ground motions combined with NCTE are simulated using the region-matching method.Peak ground acceleration(PGA),spectral acceleration at the fundamental period T1(Sa(T1)),and peak ground velocity(PGV)are compared to determine the optimal intensity measure(IM).The probabilistic seismic demand models and fragility curves are constructed.The results show that PGV is the optimal IM for ground motions considering NCTE.The NCTE can significantly increase the damage probability of CCBs.The damage probability of the side bearing is the most sensitive to NCTE among the vulnerable components.The side pier bearings and the side piers on the illuminated canyon side may be the most vulnerable components considering the NCTE effect. 展开更多
关键词 fragility analysis canyon-crossing bridge near-source canyon topographic effect intensity measure V-shaped canyon
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Effect of a semi-cylindrical weathered canyon on the seismic response of a bridge under SH waves 认领 引用
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作者 Lu Haijun Zhang Yumeng +4 位作者 Zhang Yu Wang Lin Dai Denghui Zhou Yundong Zhang Ning 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2026年第3期653-662,共10页
To investigate the canyon topography-stratigraphy effect on the dynamic response of a bridge,an analytical solution for a simply-supported bridge crossing a semi-cylindrical weathered canyon under SH waves is proposed... To investigate the canyon topography-stratigraphy effect on the dynamic response of a bridge,an analytical solution for a simply-supported bridge crossing a semi-cylindrical weathered canyon under SH waves is proposed.The simply-supported bridge is modelled as an elastic shear beam,which is supported by two rigid abutments with each having a rigid foundation embedded in half-space.The dynamic canyon-bridge interaction problem is physically decomposed into one scattering problem and two radiation problems.The proposed solution is verified by degenerating to a past exact solution for a single simply-supported bridge model in flat half-space.It is found that the surficial inhomogeneous soil layer may significantly amplify the seismic response of the bridge and foundations.The intensity of the topographic-stratigraphic amplification is influenced by the inhomogeneity and thickness of the surficial layer of the weathered canyon,as well as the frequency component and obliquity of the incident SH waves. 展开更多
关键词 dynamic canyon-bridge interaction site effect weathered canyon wave scattering and radiation wave function expansion SH waves
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Morphological Controls of Submarine Canyons on Reservoir Heterogeneity: Seismic Detection of the Matruh Canyon(Cretaceous, Egypt) and Global Deep-Water Analogues 认领 引用
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作者 Tharwat H.Abdel Hafeez Hatem E.Semary +3 位作者 Ahmed A.Essa Mohamed Fathy Anis Ben Ghorbal Haitham M.Ayyad 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2026年第3期910-933,共24页
Submarine canyons critically control reservoir heterogeneity in deep-water settings,yet their erosional surfaces often evade seismic detection.This study integrates the instantaneous phase,variance coherence,spectral ... Submarine canyons critically control reservoir heterogeneity in deep-water settings,yet their erosional surfaces often evade seismic detection.This study integrates the instantaneous phase,variance coherence,spectral whitening and acoustic impedance inversion of advanced seismic attributes to resolve the morphology of the Cretaceous Matruh Canyon(Egypt's Western Desert) and quantify its impact on the Alam El Bueib IIIG reservoir.Conventional 2D seismic data initially obscured the canyon's basal erosional surface due to velocity push-down artefacts and sparse line spacing.Our workflow successfully delineated a U-shaped,faultcontrolled incision system,revealing stark thickness variations(> 440 ft locally) where canyon infill replaced reservoir sands with sealing Matruh Shale.Paradoxically,while this erosion disrupted continuity evidenced by shale-plugged wells(e.g.,Emry Deep_04),it concurrently created stratigraphic traps through lateral sand-shale juxtaposition and shale-drape seals.Note that shale gouge ratio analysis confirmed robust lateral seals(> 80%) along bounding faults,notably where shale thickness exceeded 200 ft.We initially struggled to reconcile the abrupt transition from productive sands(Emry Deep_01X) to non-reservoir intervals until spectral whitening resolved thin( 400-m incision depth create traps distinct from post-rift carbonates or shale diapirs. 展开更多
关键词 alam el bueib formation cretaceous syn-rift basins seismic attribute analysis shale gouge ratio(SGR) stratigraphic trap formation submarine canyons
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Erosion-Dominated Modern Submarine Gully-Canyon-Channel Systems in Offshore Northwest Palawan,Southern South China Sea 认领 引用
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作者 Han Shi Weifeng Ding +2 位作者 Shaoru Yin Jinyao Gao Jiabiao Li 《Journal of Earth Science》 SCIE CAS CSCD 2026年第1期329-350,共22页
We investigated the morphology and sedimentary state of an extensive modern canyon system on the northwest continental slope of Palawan Island in the southern South China Sea using multibeam bathymetry data and chirp ... We investigated the morphology and sedimentary state of an extensive modern canyon system on the northwest continental slope of Palawan Island in the southern South China Sea using multibeam bathymetry data and chirp sub-bottom profiles.The canyon system in Northwest Palawan consists of a fairly large dendritic canyon,a braided canyon,and a set of short,straight,and slope-confined gullies.The erosion state covers 71%of the system.Sediment accumulates downstream of the bend's inner side in the proximal main stem of the dendritic canyon and is eroded in its outer side.In the distal main stem,sediment is deposited inside and outside the bend.In most of the system's tributaries,decreasing slope gradients result in more sediment deposition.There is thick aggradation of sediment waves in the interfluve throughout the system,which exhibit increasing levels of stratification as the slope decreases.The lack of slump scars and headward erosion at the canyon heads,as well as the presence of regular gullies and sediment wave fields,suggest that large areas of unconfined downslope turbidity currents formed the system.We propose that frequent storms in northwestern Palawan triggered these currents by resuspending sediments on the shelf. 展开更多
关键词 submarine canyon system modern activity multibeam bathymetry chirp sub-bottom profiles turbidity currents sedimentary processes Palawan southern South China Sea
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Suitability of using carbon dioxide as a tracer gas for studying vehicle emission dispersion in a real street canyon 认领 引用
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作者 Yuhan Huang Helen B.Wang +10 位作者 Hilda M.W.Mak Mengyuan Chu Zhi Ning Bruce Organ Edward F.C.Chan Chun-Ho Liu Wai-Chuen Mok Christof Gromke Ho Kyong Shon Chengwang Lei John L.Zhou 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2025年第9期832-845,共14页
High-rise buildings form deep urban street canyons and restrict the dispersion of vehicle emissions,posing severe health risks to the public by aggravating roadside air quality.Field measurements are important for und... High-rise buildings form deep urban street canyons and restrict the dispersion of vehicle emissions,posing severe health risks to the public by aggravating roadside air quality.Field measurements are important for understanding the dispersion process of tailpipe emissions in street canyons,while a major challenge is the lack of a suitable tracer gas.Carbon dioxide(CO2),which is safe to the public and inexpensive to obtain,can be reliably measured by existing gas analysers.This study investigated the suitability of using CO2as a tracer gas for characterising vehicle emission dispersion in a real-world street canyon.The tracer gas was released via a line or point source,whose dispersion was characterised by a sensors network comprising low-cost air quality sensors.The results showed that the CO2contained in the exhaust gas of a test vehicle itself had unmeasurable effect at roadsides.Both the line and point sources produced obvious CO2level elevations at approximately 30 s after the test vehicle passed by.In addition,for both line and point sources,the CO2elevations were much more distinct at the roadside next to tailpipe exit than the opposite side,and were higher at 0.8 m than 1.6 m above the ground.The present study demonstrated that using CO2as a tracer gas is feasible for investigating vehicle emission dispersion in real-world street canyons.Future studies are needed to improve the gas release rate of the developed tracer gas systems for more reliable measurements and larger street canyons. 展开更多
关键词 Vehicle emission dispersion Tracer gas Carbon dioxide Urban street canyon Line emission source Point emission source
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Deposition processes of gas hydrate-bearing sediments in the inter-canyon area of Shenhu Area in the northern South China Sea 认领 引用 被引量：3
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作者 Zhixuan LIN Ming SU +5 位作者 Haiteng ZHUO Pibo SU Jinqiang LIANG Feifei WANG Chengzhi YANG Kunwen LUO 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2023年第2期740-756,共17页
The Shenhu Submarine Canyon Group on the northern slope of the South China Sea consists of 17 slope-confined canyons,providing a good example for investigating their hosting sediments.Three drilling sites,including W0... The Shenhu Submarine Canyon Group on the northern slope of the South China Sea consists of 17 slope-confined canyons,providing a good example for investigating their hosting sediments.Three drilling sites,including W07,W18,and W19,have proven the occurrence of gas hydrate reservoirs in the inter-canyon area between canyons C11 and C12.Whereas,variations of the geomorphology and seismic facies analyzed by high-resolution 3D seismic data indicate that the gas hydrate-bearing sediments may form in different sedimentary processes.In the upper segment,a set of small-scale channels with obvious topographic lows can be identified,revealing fine-grained turbidites supplied from the shelf region during a very short-term sea-level lowstand.In the middle part,gas hydrate units at Site W07 showing mounded or undulation external configuration are interpreted as sliding sedimentary features,and those features caused by gravity destabilization were the main formative mechanism of gas hydrate-bearing sediments that were sourced from the upper segments.In contrast,for the canyon transition zone of lower segments between C11-C12 inter-canyon and C12 intra-canyon areas,where W18 and W19 sites are located,the gas hydratebearing sediments are deposited in the channelized feature in the middle to lower segment and slide erosive surface.Gas hydrate-bearing sediments of the lower segment were migrated through channelized features interconnecting with the middle to lower slope by gravity-driven flows.The majority of deposits tended to be furtherly moved by lateral migration via erosive surface created by sediment failed to intra-canyon area.The conclusion of this study may help better understand the interaction between the formation mechanism of gas hydrate-bearing sediments and the geomorphologic effects of inter-canyon areas. 展开更多
关键词 submarine canyons gas hydrate-bearing sediments seismic geomorphology inter-canyon transport process
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The ancient village thriving on a canyon's edge 认领 引用
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作者 杨述萍 《疯狂英语（新读写）》 2025年第5期50-51,77,共2页
The ancient village of Khunzakh,in Dagestan,is literally located on the edge of a deep canyon(峡谷),making it one of the most awe⁃inspiring human settlements in the world.Before Khabib Nurmagomedov became the undisput... The ancient village of Khunzakh,in Dagestan,is literally located on the edge of a deep canyon(峡谷),making it one of the most awe⁃inspiring human settlements in the world.Before Khabib Nurmagomedov became the undisputed(无可争辩的)champion of the UFC Lightweight Division,most people hadn't even heard of Dagestan.Today,it is almost associated with the legendary mixed martial arts master,but the Russian autonomous republic is actually home to a number of wonders that the world has yet to discover.Today,we're featuring Khunzakh,a very old village with a very unique location—right on the edge of a 100⁃meter⁃deep canyon. 展开更多
关键词 mixed martial arts Khunzakh human settlement awe inspiring canyon Dagestan ancient village UFC
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“峡谷”探险:2025 Can-Am Canyon 认领 引用
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作者 马文龙 《摩托车》 2025年第7期52-57,共6页
说到个性鲜明的摩托车,来自加拿大的Can-Am Spyder绝对榜上有名。倒三轮的结构,赋予Spyder星外来客般的“双头兽”造型,路上回头率100%;别具一格的过弯方式,让骑手体验到轿车般的驾驶感觉;健硕的3只轮胎,在猛烈制动时提供强大的稳定性;... 说到个性鲜明的摩托车,来自加拿大的Can-Am Spyder绝对榜上有名。倒三轮的结构,赋予Spyder星外来客般的“双头兽”造型,路上回头率100%;别具一格的过弯方式,让骑手体验到轿车般的驾驶感觉;健硕的3只轮胎,在猛烈制动时提供强大的稳定性;半自动传动系统,让骑手按下按钮即可方便换挡;没有前制动杆,只需用脚轻点制动踏板,由EDB将制动压力自动分配给3只车轮…… 展开更多
关键词 Can-Am Canyon 摩托车
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Scattering of SH waves induced by a symmetrical V-shaped canyon: a unified analytical solution 认领 引用 被引量：25
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作者 Zhang Ning Gao Yufeng +2 位作者 Li Dayong Wu Yongxin Zhang Fei 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2012年第4期445-460,共16页
This paper reports a series solution of wave functions for two-dimensional scattering and diffraction of plane SH waves induced by a symmetrical V-shaped canyon with different shape ratios. A half-space with a symmetr... This paper reports a series solution of wave functions for two-dimensional scattering and diffraction of plane SH waves induced by a symmetrical V-shaped canyon with different shape ratios. A half-space with a symmetrical V-shaped canyon is divided into two sub-regions by using a circular-arc auxiliary boundary. The two sub-regions are represented by global and local cylindrical coordinate systems, respectively. In each coordinate system, the wave field satisfying the Helmholtz equation is represented by the separation of variables method, in terms of the series of both Bessel functions and Hankel functions with unknown complex coefficients. Then, the two wave fields are described in the local coordinate system using the Graf addition theorem. Finally, the unknown coefficients are sought by satisfying the continuity conditions of the auxiliary boundary. To consider the phase characteristics of the wave scattering, a parametric analysis is carried out in the time domain by assuming an incident signal of the Ricker type. Surface and subsurface transient responses demonstrate the characteristics and mechanisms of wave propagating and scattering. 展开更多
关键词 SH-wave scattering V-shaped canyon topographic effect wave propagation earthquake ground motion wave function expansion method
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Depositional Characteristics and Formation Mechanisms of Deep-Water Canyon Systems along the Northern South China Sea Margin 认领 引用 被引量：17
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作者 Hui Chen Xinong Xie +3 位作者 Kainan Mao Yunlong He Ming Su Wenyan Zhang 《Journal of Earth Science》 SCIE CAS CSCD 2020年第4期808-819,共12页
Submarine canyon systems are sites for coarser clastic sediment accumulations in the deep-water domains, having the most potential for hydrocarbon reservoirs. Based on the interpretation of high resolution 2 D/3 D sei... Submarine canyon systems are sites for coarser clastic sediment accumulations in the deep-water domains, having the most potential for hydrocarbon reservoirs. Based on the interpretation of high resolution 2 D/3 D seismic and drilling data, depositional characteristics of three large deep-water canyon systems on the South China Sea northern margin have been analyzed. The Central Canyon System has a deep incision geomorphology extending from east to west, featured by distinct canyon segmentations, multi-provenance sediment supplies and multi-stage canyon fillings. The Pearl River Canyon System’s formation is closely related to the development of Pearl River Delta. Its vertical stacking and migrating canyon patterns have changed over time. The depositional architectures and evolution of the recent Penghu-Gaoping Canyon System respond to tectonic movements along the Taiwan-Luzon convergent continental margin. The main controlling factors of the formation and evolution of these three canyon systems include the tectonic setting, sediment supply, sea level change and paleo-geomorphology, among which the former two are dominant. The Penghu-Gaoping Canyon System formed along the subduction structural zone, directly indicating a typical tectonic origin. Numerous seismic data show that the Central Canyon and Pearl River Canyon systems are obviously affected by tectonics, associated local topography and sediment supply. 展开更多
关键词 deep-water canyon system turbidite channel deep-water reservoir northern margin of South China Sea
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A Laboratory Model for the Flow in Urban Street Canyons Induced by Bottom Heating 认领 引用 被引量：14
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作者 刘辉志 梁彬 +2 位作者 朱凤荣 张伯寅 桑建国 《Advances in Atmospheric Sciences》 SCIE CAS 2003年第4期554-564,共11页
Water tank experiments are carried out to investigate the convection flow induced by bottom heating and the effects of the ambient wind on the flow in non-symmetrical urban street canyons based on the PIV (Particle Im... Water tank experiments are carried out to investigate the convection flow induced by bottom heating and the effects of the ambient wind on the flow in non-symmetrical urban street canyons based on the PIV (Particle Image Visualization) technique. Fluid experiments show that with calm ambient wind, the flows in the street canyon are completely driven by thermal force, and the convection can reach the upper atmosphere of the street canyon. Horizontal and vertical motions also appear above the roofs of the buildings. These are the conditions which favor the exchange of momentum and air mass between the street canyon and its environment. More than two vortices are induced by the convection, and the complex circulation pattern will vary with time in a wider street canyon. However, in a narrow street canyon, just one vortex appears. With a light ambient wind, the bottom heating and the associated convection result in just one main vortex. As the ambient wind speed increases, the vortex becomes more organized and its center shifts closer to the leeward building. 展开更多
关键词 flow in non-symmetrical urban street canyons bottom heating water tank
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Seismic response analysis of continuous rigid frame bridge considering canyon topography effects under incident SV waves 认领 引用 被引量：10
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作者 Guoliang Zhou Xiaojun Li Xingjun Qi 《Earthquake Science》 2010年第1期53-61,共9页
To evaluate the importance of the canyon topography effects on large structures, based on a rigid frame bridge across a 137-m-deep and 600-m-wide canyon, the seismic response of the canyon site is analyzed using a two... To evaluate the importance of the canyon topography effects on large structures, based on a rigid frame bridge across a 137-m-deep and 600-m-wide canyon, the seismic response of the canyon site is analyzed using a two-dimensional finite element model under different seismic SV waves with the assumptions of vertical incidence and oblique incidence to obtain the ground motions, which are used as the excitation input on the pier foundations of the bridge with improved large mass method. The results indicate that canyon topography has significant influences on the ground motions in terms of inci- dent angle. The peak ground acceleration values vary greatly from the bottom of the canyon to the upper comers. Under ver- tical incident SV waves, at the upper comers of canyon the peak ground accelerations greatly increase; whereas the peak ground accelerations diminish at the bottom comers of canyon. Under oblique incident SV waves, the shaking of the canyon slope perpendicular to the incidence direction is much more severe than that of the opposite side of canyon. And the ground surface has been characterized by larger deformations in the case of oblique incident waves. It is also concluded that the low piers and frame of the continuous rigid frame bridge ape more sensitive to the multi-support seismic excitations than the flexible high piers. The canyon topography as well as the oblique incidence of the waves brings the continuous rigid frame bridge severe responses, which should be taken into account in bridge design. 展开更多
关键词 rigid frame bridge canyon topography effect multi-support excitation improved large-mass method seismic response
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Antiplane response of two scalene triangular hills and a semi-cylindrical canyon by incident SH-waves 认领 引用 被引量：6
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作者 Yang Zailin Xu Huanan +1 位作者 Hei Baoping Zhang Jianwei 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2014年第4期569-581,共13页
Antiplane response of two scalene triangular hills and a semi-cylindrical canyon by SH-waves is studied using wave function expansion and complex function method. Firstly, the analytical model is divided into three pa... Antiplane response of two scalene triangular hills and a semi-cylindrical canyon by SH-waves is studied using wave function expansion and complex function method. Firstly, the analytical model is divided into three parts, and the displacement solutions of wave fields are constructed based on boundary conditions in the three regions. Three domains are then conjoined to satisfy the ＂conjunction＂ condition at shared boundary. In addition, combined with the zero-stress condition of semi-cylindrical canyon, a series of infinite algebraic equations for the problem are derived. Finally, numerical examples are provided and the influence of different parameters on ground motion is discussed. 展开更多
关键词 scattering of SH-waves scalene triangle hills semi-cylindrical canyon ground motion
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Mass movements in small canyons in the northeast of Baiyun deepwater area, north of the South China Sea 认领 引用 被引量：6
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作者 LI Xishuang LIU Lejun +3 位作者 LI Jiagang GAO Shan ZHOU Qingjie SU Tianyun 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2015年第8期35-42,共8页
The process of mass movements and their consequent turbidity currents in large submarine canyons has been widely reported, however, little attention was paid to that in small canyons. In this paper, we document mass m... The process of mass movements and their consequent turbidity currents in large submarine canyons has been widely reported, however, little attention was paid to that in small canyons. In this paper, we document mass movements in small submarine canyons in the northeast of Baiyun deepwater area, north of the South China Sea （SCS）, and their strong effects on the evolution of the canyons based on geophysical data. Submarine canyons in the study area arrange closely below the shelf break zone which was at the depth of -500 m. Within submarine canyons, seabed surface was covered with amounts of failure scars resulted from past small-sized landslides. A complex process of mass transportation in the canyons is indicated by three directions of mass movements. Recent mass movement deposits in the canyons exhibit translucent reflections or parallel reflections which represent the brittle deformation and the plastic deformation, respectively. The area of most landslides in the canyons is less than 3 km2. The trigger mechanisms for mass movements in the study area are gravitational overloading, slope angle and weak properties of soil. Geophysical data indicate that the genesis of submarine canyons is the erosion of mass movements and consequent turbidity currents. The significant effects of mass movements on canyon are incision and sediment transportation at the erosion phases and fillings supply at the fill phases. This research will be helpful for the geological risk assessments and understanding the sediment transportation in the northern margin of the SCS. 展开更多
关键词 mass movement geophysical data trigger mechanism submarine canyon north of the South China Sea
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Difference in full-filled time and its controlling factors in the Central Canyon of the Qiongdongnan Basin 认领 引用 被引量：6
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作者 SHANG Zhilei XIE Xinong +4 位作者 LI Xushen ZHANG Daojun HE Yunlong YANG Xing CUI Mingzhe 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2015年第10期81-89,共9页
Based on the interpretation of high resolution 2D/3D seismic data, sedimentary filling characteristics and full- filled time of the Central Canyon in different segments in the Qiongdongnan Basin of northwestern South ... Based on the interpretation of high resolution 2D/3D seismic data, sedimentary filling characteristics and full- filled time of the Central Canyon in different segments in the Qiongdongnan Basin of northwestern South China Sea have been studied. The research results indicate that the initial formation age of the Central Canyon is traced back to 11.6 Ma （T40）, at which the canyon began to develop due to the scouring of turbidity currents from west to east. During the period of 11.6-8.2 Ma （T40-T31）, strong downcutting by gravity flow occurred, which led to the formation of the canyon. The canyon fillings began to form since 8.2 Ma （T31） and were dominated by turbidite deposits, which constituted of lateral migration and vertical superposition of turbidity channels during the time of 8.2-5.5 Ma. The interbeds of turbidity currents deposits and mass transport deposits （MTDs） were developed in the period of 5.5-3.8 Ma （T30-T28）. After then, the canyon fillings were primarily made up of large scale MTDs, interrupted by small scale turbidity channels and thin pelagic mudstones. The Central Canyon can be divided into three types according to the main controlling factors, geomorphology-controlled, fault-controlled and intrusion- modified canyons. Among them, the geomorphology-controlled canyon is developed at the Ledong, Lingshui, Songnan and western Baodao Depressions, situated in a confined basin center between the northern slope and the South Uplift Belt along the Central Depression Belt. The fault-controlled canyon is developed mainly along the deep-seated faults in the Changchang Depression and eastern Baodao Depression. Intrusion-modified canyon is only occurred in the Songnan Low Uplift, which is still mainly controlled by geomorphology, the intrusion just modified seabed morphology. The full-filled time of the Central Canyon differs from west to east, displaying a tendency of being successively late eastward. The geomorphology-controlled canyon was completely filled before 3.8 Ma （T28）, but that in intrusion-modified canyon was delayed to 2.4 Ma （T27） because of the uplifted southern canyon wall. To the Changchang Depression, the complete filling time was successively late eastward, and the canyon in eastern Changchang Depression is still not fully filled up to today. Difference in full-filled time in the Central Canyon is mainly governed by multiple sediment supplies and regional tectonic activities. Due to sufficient supply of turbidity currents and MTDs from west and north respectively, western segment of the Central Canyon is entirely filled up earlier. Owing to slower sediment supply rate, together with differential subsidence by deep-seated faults, the full-filled time of the canyon is put off eastwards gradually. 展开更多
关键词 South China Sea Qiongdongnan Basin Central Canyon sedimentary filling full-filled time
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2.5D scattering of incident plane SV waves by a canyon in layered half-space 认领 引用 被引量：13
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作者 Ba Zhenning Liang Jianwen 《Earthquake Engineering and Engineering Vibration》 SCIE EI 2010年第4期587-595,共9页
This paper presents a 2.5D scattering of incident plane SV waves by a canyon in a layered half-space by using the indirect boundary element method （IBEM）. A free field response analysis is performed to provide the d... This paper presents a 2.5D scattering of incident plane SV waves by a canyon in a layered half-space by using the indirect boundary element method （IBEM）. A free field response analysis is performed to provide the displacements and stresses on the boundary of the canyon where fictitious uniform moving loads are applied to calculate the Green＇s fi.mctions for the displacements and stresses. The amplitudes of the loads are determined by the boundary conditions. The free field displacements are added to the fictitious uniform moving loads induced displacements and the total response is obtained. Numerical calculations are performed for a canyon with homogenous and in one layer over bedrock. The effects of the thickness and stiffness of the layer on the amplification are studied and discussed. 展开更多
关键词 layered half-space canyon plane SV wave amplification scattering surface layer indirect boundaryelement method
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Numerical Study on the Impact of Ground Heating and Ambient Wind Speed on Flow Fields in Street Canyons 认领 引用 被引量：5
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作者 李磊 杨琳 +1 位作者 张立杰 江崟 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2012年第6期1227-1237,共11页
The impact of ground heating on flow fields in street canyons under different ambient wind speed conditions was studied based on numerical methods. A series of numerical tests were performed, and three factors includi... The impact of ground heating on flow fields in street canyons under different ambient wind speed conditions was studied based on numerical methods. A series of numerical tests were performed, and three factors including height-to-width （H/W） ratio, ambient wind speed and ground heating intensity were taken into account. Three types of street canyon with H/W ratios of 0.5, 1.0 and 2.0, respectively, were used in the simulation and seven speed values ranging from 0.0 to 3.0 m s-1 were set for the ambient wind speed. The ground heating intensity, which was defined as the difference b-ween the ground temperature and air temperature, ranged from 10 to 40 K with an increase of 10 K in the tests. The results showed that under calm conditions, ground heating could induce circulation with a wind speed of around 1.0 m s-i, which is enough to disperse pollutants in a street canyon. It was also found that an ambient wind speed threshold may exist for street canyons with a fixed H/W ratio. When ambient wind speed was lower than the threshold identified in this study, the impact of the thermal effect on the flow field was obvious, and there existed a multi-vortex flow pattern in the street canyon. When the ambient wind speed was higher than the threshold, the circulation pattern was basically determined by dynamic effects. The tests on the impact of heating intensity showed that a higher ground heating intensity could strengthen the vortical flow within the street canyon, which would help improve pollutant diffusion capability in street canyons. 展开更多
关键词 street canyon thermal effect ambient wind ground heating intensity computational fluid dynamics （CFD）
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Seismic analysis of high-speed railway irregular bridge–track system considering V-shaped canyon effect 认领 引用 被引量：7
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作者 Zhihui Zhu Yongjiu Tang +2 位作者 Zhenning Ba Kun Wang Wei Gong 《Railway Engineering Science》 2022年第1期57-70,共14页
To explore the effect of canyon topography on the seismic response of railway irregular bridge-track system that crosses a V-shaped canyon, seismic ground motions of the horizontal site and V-shaped canyon site were s... To explore the effect of canyon topography on the seismic response of railway irregular bridge-track system that crosses a V-shaped canyon, seismic ground motions of the horizontal site and V-shaped canyon site were simulated through theoretical analysis with 12 earthquake records selected from the Pacific Earthquake Engineering Research Center(PEER) Strong Ground Motion Database matching the site condition of the bridge.Nonlinear seismic response analyses of an existing 11-span irregular simply supported railway bridge-track system were performed under the simulated spatially varying ground motions. The effects of the V-shaped canyon topography on the peak ground acceleration at bridge foundations and seismic responses of the bridge-track system were analyzed. Comparisons between the results of horizontal and V-shaped canyon sites show that the top relative displacement between adjacent piers at the junction of the incident side and the back side of the V-shaped site is almost two times that of the horizontal site, which also determines the seismic response of the fastener. The maximum displacement of the fastener occurs in the V-shaped canyon site and is 1.4 times larger than that in the horizontal site. Neglecting the effect of V-shaped canyon leads to the inappropriate assessment of the maximum seismic response of the irregular high-speed railway bridge-track system. Moreover, engineers should focus on the girder end to the left or right of the two fasteners within the distance of track seismic damage. 展开更多
关键词 V-shaped canyon Nonlinear seismic response Irregular bridge Simply supported railway bridge Analytical solution Topography effect
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Formation of the Huajiang Grand Canyon (southwestern China) driven by the evolution of a Late Pleistocene tiankeng 认领 引用 被引量：2
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作者 Yunlong Fan Andrea Columbu +4 位作者 Kangning Xiong Guangjie Luo Song Li Xuefeng Wang Yangyang Wu 《Acta Geochimica》 EI CAS CSCD 2022年第1期1-11,共11页
Collapse is a common geomorphic process in karst areas,especially on the Yunnan-Guizhou Plateau,which has a tectonic background of integral uplift.The frequent occurrence of collapse processes in karst underground cav... Collapse is a common geomorphic process in karst areas,especially on the Yunnan-Guizhou Plateau,which has a tectonic background of integral uplift.The frequent occurrence of collapse processes in karst underground caves and canyons indicates that collapses play an important role in the formation of canyons.Through an analysis of the morphology of a semicircular cliff in the Huajiang Grand Canyon and an investigation of sediments at the bottom of the cliff,a large-scale collapse event was found to have occurred.U-series dating of secondary calcium carbonate cement in the collapse breccias indicates that collapse processes occurred approximately 200 ka.According to the geomorphological evolution of the Huajiang Grand Canyon,the following geomorphic evolutionary process is proposed:underground river-cave hall-collapse of a tiankeng-tiankeng degradation-canyon formation.These findings also show that the dating of collapsed breccia cement can be effectively used to determine the development times of karst canyons and the formation ages of tiankengs. 展开更多
关键词 Canyon Cave collapse Tiankeng Karst breccias Yunnan-Guizhou Plateau
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A buried submarine canyon in the northwestern South China Sea: architecture, development processes and implications for hydrocarbon exploration 认领 引用 被引量：2
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作者 Bin Wang Fuliang Lü +10 位作者 Shuang Li Jian Li Zhili Yang Li Li Xuefeng Wang Yintao Lu Taotao Yang Jingwu Wu Guozhong Sun Hongxia Ma Xiaoyong Xu 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2021年第2期29-41,共13页
High-resolution multichannel seismic data enables the discovery of a previous,undocumented submarine canyon(Huaguang Canyon)in the Qiongdongnan Basin,northwestern South China Sea.The Huaguang Canyon with a NW orientat... High-resolution multichannel seismic data enables the discovery of a previous,undocumented submarine canyon(Huaguang Canyon)in the Qiongdongnan Basin,northwestern South China Sea.The Huaguang Canyon with a NW orientation is 140 km in length,and 2.5 km to 5 km in width in its upper reach and 4.6 km to 9.5 km in width in its lower reach.The head of the Huaguang Canyon is close to the Xisha carbonate platform and its tail is adjacent to the Central Canyon.This buried submarine canyon is formed by gravity flows from the Xisha carbonate platform when the sea level dropped in the early stage of the late Miocene(around 10.5 Ma).The internal architecture of the Huaguang Canyon is mainly characterized by high amplitude reflections,indicating that this ancient submarine canyon was filled with coarse-grained sediments.The sediment was principally scourced from the Xisha carbonate platform.In contrast to other buried large-scale submarine canyons(Central Canyon and Zhongjian Canyon)in the Qiongdongnan Basin,the Huaguang Canyon displays later formation time,smaller width and length,and single sediment supply.The coarse-grained deposits within the Huaguang Canyon provide a good environment for reserving oil and gas,and the muddy fillings in the Huaguang Canyon have been identified as regional caps.Therefore,the Huaguang Canyon is a potential area for future hydrocarbon exploration in the northwestern South China Sea.The result of this paper may contribute to a better understanding of the evolution of submarine canyons formed in carbonate environment. 展开更多
关键词 South China Sea Qiongdongnan Basin submarine canyon evolution
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