Negative skin friction (NSF) is one of the important problems when designing a pile foundation. However, the influence of loading sequence on the dragload and downdrag for pile foundation is seldom studied. In this pa...Negative skin friction (NSF) is one of the important problems when designing a pile foundation. However, the influence of loading sequence on the dragload and downdrag for pile foundation is seldom studied. In this paper, a three-dimensional numerical model was established using FLAC3D. Compared with the results of model test, the established model could be used to study the NSF of pile foundation. The influencing factors were discussed including the length-diameter ratio of pile and the loading sequence of pile head load and surcharge. A case history was analyzed using FLAC3D. The calculated results are in good agreement with the measured results. It is concluded that the dragload and downdrag are remarkably influenced by the loading sequence of pile head load and surcharge. The dragload and downdrag reach the maximum values under the condition of surcharge after pile head load.展开更多
This paper reports some results of geo-scientific evaluation of the petroleum systems in the northeastern area of the Song Hong Basin offshore Vietnam. Geological-geophysical data, including regional studies, 2D and 3...This paper reports some results of geo-scientific evaluation of the petroleum systems in the northeastern area of the Song Hong Basin offshore Vietnam. Geological-geophysical data, including regional studies, 2D and 3D seismic ＆ logging interpretation results as well as core/cutting samples analysis were integrated to reveals that the north-eastern area were controlled by pull apart activities along Song Hong river fault system, rifting phase during Eocene-Oligocene and subsidence during Miocene-Quaternary. Inversion activities at the end of Oligocene and late Miocene also play very important roles. These activities convert Pre-tertiary carbonate basement rocks to be potential reservoirs. The main source rock, overlying and adjacent to basement highs, was deposited in the lacustrine environment during rifting phase of Eocene and Oligocene and is still at the depth of oil generation window. The mentioned source rock layer is also considered as a good top seal for the basement. Petroleum system has been proven by the drilling and testing results and the studied area become more attractive and have higher chance of success.展开更多
In recent years,three-dimensional topological insulators(3DTI) as a novel state of quantum matter have become a hot topic in the fields of condensed matter physics and materials sciences.To fulfill many spectacularly ...In recent years,three-dimensional topological insulators(3DTI) as a novel state of quantum matter have become a hot topic in the fields of condensed matter physics and materials sciences.To fulfill many spectacularly novel quantum phenomena predicted in 3DTI,real host materials are of crucial importance.In this review paper,we first introduce general methods of searching for new 3DTI based on the density-functional theory.Then,we review the recent progress on materials realization of 3DTI including simple elements,binary compounds,ternary compounds,and quaternary compounds.In these potential host materials,some of them have already been confirmed by experiments while the others are not yet.The 3DTI discussed here does not contain the materials with strong electron-electron correlation.Lastly,we give a brief summary and some outlooks in further studies.展开更多
基金Supported by National Natural Science Foundation of China (No.50679015)China Postdoctoral Science Foundation (No.20090461062)
文摘Negative skin friction (NSF) is one of the important problems when designing a pile foundation. However, the influence of loading sequence on the dragload and downdrag for pile foundation is seldom studied. In this paper, a three-dimensional numerical model was established using FLAC3D. Compared with the results of model test, the established model could be used to study the NSF of pile foundation. The influencing factors were discussed including the length-diameter ratio of pile and the loading sequence of pile head load and surcharge. A case history was analyzed using FLAC3D. The calculated results are in good agreement with the measured results. It is concluded that the dragload and downdrag are remarkably influenced by the loading sequence of pile head load and surcharge. The dragload and downdrag reach the maximum values under the condition of surcharge after pile head load.
文摘This paper reports some results of geo-scientific evaluation of the petroleum systems in the northeastern area of the Song Hong Basin offshore Vietnam. Geological-geophysical data, including regional studies, 2D and 3D seismic ＆ logging interpretation results as well as core/cutting samples analysis were integrated to reveals that the north-eastern area were controlled by pull apart activities along Song Hong river fault system, rifting phase during Eocene-Oligocene and subsidence during Miocene-Quaternary. Inversion activities at the end of Oligocene and late Miocene also play very important roles. These activities convert Pre-tertiary carbonate basement rocks to be potential reservoirs. The main source rock, overlying and adjacent to basement highs, was deposited in the lacustrine environment during rifting phase of Eocene and Oligocene and is still at the depth of oil generation window. The mentioned source rock layer is also considered as a good top seal for the basement. Petroleum system has been proven by the drilling and testing results and the studied area become more attractive and have higher chance of success.
基金supported by the National Basic Research Program of China (Grants No.2011CBA00100)the National Natural Science Foundation of China(Grant Nos.10974231 and 11174337)
文摘In recent years,three-dimensional topological insulators(3DTI) as a novel state of quantum matter have become a hot topic in the fields of condensed matter physics and materials sciences.To fulfill many spectacularly novel quantum phenomena predicted in 3DTI,real host materials are of crucial importance.In this review paper,we first introduce general methods of searching for new 3DTI based on the density-functional theory.Then,we review the recent progress on materials realization of 3DTI including simple elements,binary compounds,ternary compounds,and quaternary compounds.In these potential host materials,some of them have already been confirmed by experiments while the others are not yet.The 3DTI discussed here does not contain the materials with strong electron-electron correlation.Lastly,we give a brief summary and some outlooks in further studies.
