The Lift Forces Acting on a Submarine Composite Pipeline in a Wave-Current Coexisting Field     

Li Yucheng  Zhang Ningchuan Professor  Dalian University of Technology  Dalian . Lecturere  Delian University of Technology  Dalian 《中国海洋工程》1994,(1)

- A composite pipeline is defined as a main big pipe composed of one or several small pipes. The flow behaviour around a submarine composite pipeline is more complicated than that around a single submarine pipeline. A series model test of composite pipelines in a wave-current coexisting field was conducted by the authors. Both in-line and lift forces were measured, and the resultant forces were also analyzed. The results of lift forces and resultant forces are reported in this paper. It is found that the lift force coefficients for composite pipelines are well related to the KC number. The lift force coefficients for an irregular wave-current coexisting field are smaller than those for a regular wave-current coexisting field. The frequency of lift force is usually twice the wave frequency or higher. The authors test indicates that the resultant forces are about 10 to 20 percent larger than in-line forces (horizontal forces). The effect of water depth is analyzed. Finally, the relationship between lift f  相似文献   

Pressure Tight Piston Corer ——A New Approach on Gas Hydrate Investigation     

秦华伟顾临怡  李世伦朱亮 陈鹰 《中国海洋工程》2005,19(1):121-128

A pressure tight sediment samphng technology, which can be introduced into the modification of the piston corer to accommedate the investigation of gas hydrate, is put forward. In this paper, the three basic rules of the technology are analyzed in detail: specimen transferring rule, seal self-tightening rule and semi-active pressure holding rule. Based on these, the structure of the pressure tight piston corer is put forward and its working principle is analyzed. Finally, a pressure tight sediment sampler, to which the same technology is apphed, is researched through experiments. Results show that the sampler based on the above-mentioned theory has a good ability in samphng and in -situ pressure holding.  相似文献   

An Engineering Computational Method of Calculating Wave Forces on the Mat and Platform''''s Sit-on-Bottom Stability     

Gu Jianming Pan Bin Postgraduate  Dept. of Naval Architecture  Ocean Engineering  Shanghai Jiao Tong University  Shanghai Lecturer  Dept. of Naval Architecture  Ocean Engineering  Shanghai Jiao Tong University  Shanghai 《中国海洋工程》1993,(1)

- In this paper, an engineering method is employed to calculate the horizontal and vertical wave forces on the mat of the submersible platform under Froude-Krylov hypothesis. According to some model tests, appropriate diffraction coefficients are selected. And the results of the formulae given in the paper agree satisfactorily with those experimental data now available. The proposed computational method is effective and convenient to use in evaluating the horizontal and vertical wave forces on the mat. An exmaple is also given in this paper. Finally, the effects of the vertical wave force on the platorm's sit-on-bottom stability are analyzed.  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   

A Review of Studies on the Interaction Between Waves and Muddy Bottom     

Zhao Zidan Professor  Doctoral Supervisor  Tianjin University  Tianjin 《中国海洋工程》1992,(2)

This paper presents a brief review of the results on the interaction between waves and muddy bottom obtained during the last decade including the results obtained by the author at the Coastal Engineering Laboratory of Tianjin University.  相似文献   

Discharge Control on Boundary of Tidal Models and Measuring Techniques of Low Current Velocity     

Li Guochen Xu Jinhuan Associate Prof.  Dept. of Navigation  Ocean Eng.  Hohai University  Nanjing Lecturer  Dept. of Navigation  Ocean Eng.  Hohai University  Nanjing 《中国海洋工程》1992,(3)

This paper describes the discharge control technique on boundary used in two models, one is the model of hot water drainning in Dayawan Nyclear Power Plant, Guangdong, and the other is the model for trainhing the sand bar at the Guanhe Estuary, Jiangsu. Many years of application shows that this technique has the advantages of good reliability, repeatability and validity. The speedometer of hydrogen bubble is also introduced in this paper. The device can display and store tracing lines in a computer, and help operators to obtain the value and direction of transient velocity of a nonsteady current, thus, the problem of measurment of low current velocity in tidal model tests is solved and the automation of the measurement of current velocity is realized.  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   

Modulus of Subgrade Reaction for Laterally Loaded Piles in Multiple Layered Foundation   总被引：1，自引：1，他引：1  

Lu Ziai Associate Professor  Dept. of Navigation  Ocean Engineering  Hohai University  Nanjing 《中国海洋工程》1997,(4)

-According to the field test data of laterally loaded steel piles at home and abroad,an empiri-cal formula for evaluating the modulus of subgrade reaction under static load in layered soil is proposed.The suggested formula takes account of not only non-linearity of K_s with the depth but also its variationwith the load.It is shown that the computed bending moments along the pile shaft and the deflection atthe pile top are consistent with the measured ones.  相似文献   

Hydroelastic Response Analysis of Mat-Like VLFS over A Plane Slope in Head Seas   总被引：2，自引：0，他引：2  

孙辉  崔维成  刘应中  廖世俊 《中国海洋工程》2003,17(3)

1 .IntroductionIntheexploitationofoceanresourcesandintheutilizationofoceanspaces,verylargefloatingstructures (VLFS)suchasMega FloatinJapan (Isobe ,1 999)andMobileOffshoreBase (MOB)inUSA (Remmers ,1 999)playasignificantrole .However,owingtotheirlargesizesandrelativelylowbendingrigidities ,theirhydroelasticresponsesinwavesareofthemostconcern .ManystudieshavebeencarriedoutforthepredictionofthehydroelasticresponsesofVLFS′s (Kashiwagi,2 0 0 0 ;Cui,2 0 0 2 ) .However,inalmostallofthesestu…  相似文献   

NotesBenthic foraminiferal distribution in surface sediments along continental slope of the southern Okinawa Trough: dependance on water masses and food supply     

Xiang Rong  Li Tiegang  Yang Zuosheng  Yan Jun  Cao Qiyuan College of Marine Geosciences  Ocean University of China 《海洋学报(英文版)》2003,(1)

Benthic foraminiferal analysis of 29 samples in surface sediments from the southern Okinawa Trough is carried out. The results indicate that benthic foraminiferal abundance decreases rapidly with increasing water depth. Percentage frequencies of agglutinated foraminifera further confirm the modern shallow carbonate lysocline in the southern Okinawa Trough. From continental shelf edge to the bottom of Okinawa Trough, benthic foraminiferal fauna in the surface sediments can be divided into 5 assemblages: (1) Continental shelf break assemblage, dominated by Cibicides pseudoungerianus, corresponds to subsurface water mass of the Kuroshio Current; (2) upper continental slope assemblage, dominated by Cassidulina carinata , Globocassidulina subglobosa, corresponds to intermediate water mass of the Kuroshio Current; (3) intermediate continental slope assemblage, dominated by Uvigerina hispi-da, corresponds to the Okinawa Trough deep water mass above the carbonate lysocline; (4) lower continental slope- trough b  相似文献