Velocity and Sediment Concentration Profiles in Sediment-Laden Flows     

杨树清  Soon-KeatTAN  Siow-YongLIM 《中国海洋工程》2004,18(2):229-244

A theoretical analysis of velocity profiles in sediment-laden flows is presented by means of Prandtl-Karman mixing length theorem. The study shows that the upward velocity of liquid-phase caused by settling sediment leads to the invalidity of the log-law and Rouse equation. The theoretical analysis takes into account the upward velocity and shows: 1) the mean velocity in sediment-laden flows follows the log-law, but the Karman constant reduces in the main flow region, 2) sediment concentration reduces the mixing length of fluid particles, 3) flow resistance reduces with the presence of sediment concentration, and 4) the sediment concentration profile deviates from the well know Rouse equation. The experimental data agree well with the equations derived on the basis of non-zero wall velocity. It is found that the wall-normal velocity should not be neglected for density gradient flows because it induces more than for pure water flows.  相似文献   

Brief Account of Breakwater Construction in China     

Chai Changqing Chief Engineer  First Navigational Engineering Bureau  Ministry of Communications of China  Jianjin 《中国海洋工程》1994,(1)

-The construction of breakwaters in China in more than 40 years since the founding of the People's Republic of China is reviewed. The construction of two main types of breakwater, upright breakwaters and rubble mound breakwaters, and the way in which they are built are expounded. Recommendations to improve the technology for future breakwater construction are presented.  相似文献   

Finite Element Method for Design of Reinforced Concrete Offshore Platforms     

Song Yupu  Wang Jian Associate Professor  Dept. of Civil Engineering  Dalian University of Technology  Dalian Lecturer  Dept. of Civil Engineering  Dalian University of Technology  Dalian 《中国海洋工程》1992,(1)

A design method of reinforced concrete (R. C.) offshore platforms with nonlinear finite element analysis is proposed. According to the method, a computer program is developed. In this program nonlinear constitutive relationships and strength criteria of concrete and steel bars are included, and the progressive cracking and crushing of the concrete are taken into account. Based on the stress distribution obtained by the nonlinear finite element analysis, the amount of reinforcement in the control sections can be computed and adjusted automatically by the program to satisfy the requirement of the design. The amount of reinforcement required in the control sections, which are obtained with the nonlinear finite element analysis, is agreeable to that obtained in the experiment. This shows that the design method of R. C. offshore platform with the nonlinear finite element method proposed by the authors is reliable for practical use.  相似文献   

Stochastic Response Analysis of Piled Offshore Platforms to Earthquake Load   总被引：1，自引：0，他引：1  

Zhang Lifu Luo Chuanxin Engineer 《中国海洋工程》1993,(2)

- In this paper, using the theory of stochastic analysis of the response to earthquake load, a stochastic analysis method of the response of piled platforms to earthquake load has been established. In the method, the strong ground motion is considered as three dimensional stationary white noise process and the pile-soil interaction and water-structure interaction are considered. The stochastic response of a typical platform to eqrthquake load has been computed with this method and the results compared with those obtained with the response spectrum analysis method. The comparison shows that the stochastic analysis method of the response of piled platforms to earthquake load is suitable for this kind of analysis.  相似文献   

The Shielding Effect of Multi-Pile Structures on Ice Force     

史庆增  黄焱宋安 《中国海洋工程》2004,18(2):197-206

The shielding effect of the front pile-row on the ice force acting on the hack pile-row is studied by ice force model tests. In the tests, the front pile-row is designed to model jacket legs and the hack pile-row to model the water resisting pipe-phalanx within the jacket. The shielding factor for ice force corresponding to different conditions are given in this paper. The research indicates that there are many factors, including the longitudinal and lateral spacing between the front and hack pile-row, ice attacking angle and the ratio of pile diameter to ice thickness, that influence the shielding effect on ice force.  相似文献   

遥感、GIS结合与区域天然滑坡调查   总被引：4，自引：0，他引：4       下载免费PDF全文

单新建  李焯芬等 《地质论评》2001,47(6):648-652

以香港大屿山岛中部为试验研究区，探讨了遥感与GIS结合在区域滑坡调查中应用的可能性。在详细分析滑坡与环境因子关系后，将岩土类型、地貌、侵蚀、坡度等环境因子引入到影像中，与影像组成多源复合图像，可使地物的空间属性信息得到补充。同时采用适合高维复合数据的BP神经元网络对研究区天然滑坡进行识别，结果表明，区域滑坡的识别能力有较大提高。该方法的应用，将为大区域滑坡调查与监测奠定基础。  相似文献   

CHARACTERISTICS OF SEDIMENT TRANSPORT AND CHANNEL FORMATION BY FLOODS AT HYPERCONCENTRATIONS OF SEDIMENT IN THE YELLOW RIVER     

QI Pu  ZHAO Yean Engineer  Institute of Hydraulic Research  Yellow River Conservancy Commission Engineer  Institute of Hydraulic Research  Yellow River Conservancy Commission 《国际泥沙研究》1993,(1)

1. INTRODUCTIONThe Yellow River is a heavily sediment--laden river. Floods at Hyperconcentrationso f sediment (hereinafter simply referred to as hyperconcentrated flood) frequently occurring in the main river and its tributaries possess different characteristics of sedimenttransport. Sometimes they cause severe deposition whereas at other times they are capable of carrying substantial amount of sediment over long distances. The study on the lawof sediment transport is of significance to …  相似文献   

THE OPERATION MODE OF “STORING THE CLEAR WATER AND DISCHARGING THE MUDDY FLOW” FOR RESERVOIRS BUILT ON HEAVILY SILT-LADEN RIVERS——A CASE STUDY OF THE SANMENXIA RESERVOIR     

WenxueLI YuanfengZHANG CuipingZHANG 《国际泥沙研究》2005,20(2):109-116

Observation of the operation of the Sanmenxia Reservoir on the Yellow River has led to the conclusion that to preserve a certain effective storage volume for reservoirs built on heavily silt-laden rivers is feasible if the reservoir is operated according to the principle known as“storing the clear water and discharging the muddy flow”. The relative stability of the bed elevation at the end of the backwater and the reservoir‘s erosion and deposition equilibrium depend on the compatibility of the pool level maintained in non-flood seasons with the conditions of flow and sediment load during flood seasons. Operating the reservoir to regulate the flood and sediment load during flood seasons can reduce the rate ofaggradation in the Lower Yellow River. The basic condition for applying the operation mode of “storing the clear water and discharging the muddy flow” is that a sufficient amount of water should be used for discharging sediment during flood seasons. Under the condition of extremely low flow years, reservoir sedimentation cannot be avoided even if this operation mode is adopted.  相似文献   

瑞利波勘探中"之"字形频散曲线研究   总被引：55，自引：11，他引：44  

张碧星  鲁来玉  鲍光淑 《地球物理学报》2002,45(2):263-274

研究了弹性层状半空间中导波的多模性问题,说明了关于瑞利波勘探中"之"字形频散曲线的形成机理.证明由单个的导波模式不可能得到"之"字形频散曲线,并从能量的角度出发,研究了各模式的实际强度与地层参数的关系,克服了从相速度的角度解释"之"字形频散曲线的困难.还深入研究了地表下低速层介质的位置、厚度及其他参数对"之"字形频散曲线的相互影响.与实际资料进行了对比分析,理论结果和实际情况基本相符.  相似文献   

The reflection and transmission of elastic waves at a interface between a transversely isotropic elastic soils and saturated soils     

YA YUAN HU LI ZHONG WANG YUN MIN CHEN SHI MING WU The Civil Engineering Department of Zhejiang University  Hangzhou  China 《地震学报(英文版)》1998,(6)

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