A numerical study of linear wave scattering over a floating platform has been simulated by an efficient numericalmodel in this letter.The non-hydrostatic model is used to simulate the free surface and the uneven botto...A numerical study of linear wave scattering over a floating platform has been simulated by an efficient numericalmodel in this letter.The non-hydrostatic model is used to simulate the free surface and the uneven bottom.For thesolid body modelling,the immersed boundary method(IBM)is implemented by introducing a virtual boundaryforce into the momentum equations to emulate the boundary conditions.This implementation enhances theability of the model to simulate interactions between waves and floating structures.A numerical case involvingwave interactions with a floating platform is studied to validate the numerical model.By simulating the wavepropagation,the numerical model captures the variation of the wave scattering very well,which verifies theperformance of the numerical model and the robust strategy of the IBM.展开更多
During Permian and Triassic the western margin of Upper Yangtze platform had experienced an evolution from early rift stage to thermal subsidence and then to foreland basin. The tectonic transformations have resulted...During Permian and Triassic the western margin of Upper Yangtze platform had experienced an evolution from early rift stage to thermal subsidence and then to foreland basin. The tectonic transformations have resulted in five supersequences and nineteen third-order se- quences.During the rift stage,transgeressive carbonate platform was built up,while in the thermal subsidence stage,regressive carbonate platform with foreslope was formed.The closure of the Garze-Litang narrow oceanic basin resulted in the migration of foreland flexure toward the ctaton.The carbonate ramp in foreland basin setting was formed during the relative sea level rise which was caused by the change in basin volume.展开更多
The Cambrian of the North China platform consists chiefly of shallow water deposits and shows the sedimentary characters of an epicontinental sea basin. Controlled mainly by global sea level changes and sedimentary in...The Cambrian of the North China platform consists chiefly of shallow water deposits and shows the sedimentary characters of an epicontinental sea basin. Controlled mainly by global sea level changes and sedimentary influx, the depositional sequences all exhibit as composite sequences. From bottom upward, 14 sequences (3rd order) are recognized, which may be grouped into 5 sequence sets and further into 2 mesosequences (2nd order). It is suggested herein that the Cambrian/Ordovician boundary may better be set at the MFS (maximum flooding surface) of the sequence OSq1, above which the conodont Cordylodus lindstroemi occurs. This position is about 40 m above the traditional Cambrian/Ordovician boundary and is within the Yeli Formation.展开更多
Ocean platforms are subjected to a variety of environment loads,such as those from winds,waves,currents,etc.In this study,the torsion problems of a gravity platform column with cracks under wind load were investigated...Ocean platforms are subjected to a variety of environment loads,such as those from winds,waves,currents,etc.In this study,the torsion problems of a gravity platform column with cracks under wind load were investigated.The column was assumed to be a composite cylinder.Therefore the torsion fracture problem of a composite cylinder was considered,and new boundary integral equations for the Saint-Venant torsion problem of a composite cylinder with curvilinear cracks were derived.The problem was reduced to solving the boundary integral equations on every boundary.By using the new boundary element method,the torsion problem of the gravity platform column with a straight crack under various wind loads was calculated.The obtained results were compared with those obtained for a torsion problem of the same column without cracks to prove the applicability of the present method.The comparison showed that the detrimental effect of cracks in a column should be considered in marine engineering.展开更多
基金supported by Shanghai 2021“Science and Technology Innovation Action Plan”:Scientific and Technological Projects for Social Development(Grant No.21DZ1202701).
文摘A numerical study of linear wave scattering over a floating platform has been simulated by an efficient numericalmodel in this letter.The non-hydrostatic model is used to simulate the free surface and the uneven bottom.For thesolid body modelling,the immersed boundary method(IBM)is implemented by introducing a virtual boundaryforce into the momentum equations to emulate the boundary conditions.This implementation enhances theability of the model to simulate interactions between waves and floating structures.A numerical case involvingwave interactions with a floating platform is studied to validate the numerical model.By simulating the wavepropagation,the numerical model captures the variation of the wave scattering very well,which verifies theperformance of the numerical model and the robust strategy of the IBM.
文摘During Permian and Triassic the western margin of Upper Yangtze platform had experienced an evolution from early rift stage to thermal subsidence and then to foreland basin. The tectonic transformations have resulted in five supersequences and nineteen third-order se- quences.During the rift stage,transgeressive carbonate platform was built up,while in the thermal subsidence stage,regressive carbonate platform with foreslope was formed.The closure of the Garze-Litang narrow oceanic basin resulted in the migration of foreland flexure toward the ctaton.The carbonate ramp in foreland basin setting was formed during the relative sea level rise which was caused by the change in basin volume.
文摘The Cambrian of the North China platform consists chiefly of shallow water deposits and shows the sedimentary characters of an epicontinental sea basin. Controlled mainly by global sea level changes and sedimentary influx, the depositional sequences all exhibit as composite sequences. From bottom upward, 14 sequences (3rd order) are recognized, which may be grouped into 5 sequence sets and further into 2 mesosequences (2nd order). It is suggested herein that the Cambrian/Ordovician boundary may better be set at the MFS (maximum flooding surface) of the sequence OSq1, above which the conodont Cordylodus lindstroemi occurs. This position is about 40 m above the traditional Cambrian/Ordovician boundary and is within the Yeli Formation.
基金supported by the National High-Technology Research and Development Program of China (No.2007AA09Z317)
文摘Ocean platforms are subjected to a variety of environment loads,such as those from winds,waves,currents,etc.In this study,the torsion problems of a gravity platform column with cracks under wind load were investigated.The column was assumed to be a composite cylinder.Therefore the torsion fracture problem of a composite cylinder was considered,and new boundary integral equations for the Saint-Venant torsion problem of a composite cylinder with curvilinear cracks were derived.The problem was reduced to solving the boundary integral equations on every boundary.By using the new boundary element method,the torsion problem of the gravity platform column with a straight crack under various wind loads was calculated.The obtained results were compared with those obtained for a torsion problem of the same column without cracks to prove the applicability of the present method.The comparison showed that the detrimental effect of cracks in a column should be considered in marine engineering.
