A Finite Element Solution of Wave Forces on Submerged Horizontal Circular Cylinders

In this paper, a numerical model is established for estimating the wave forces on a submerged horizontal circular cylinder. For predicting the wave motion, a set of two-dimensional Navier-Stokes equations is solved numerically with a finite element method. In order to track the moving non-linear wave surface boundary, the Navier-Stokes equations are discretized in a moving mesh system. After each computational time step, the mesh is modified according to the changed wave surface boundary. In order to stabilize the numerical procedure, a three-step finite element method is applied in the time integration. The water sloshing in a tank and wave propagation over a submerged bar are simulated for the first time to validate the present model. The computational results agree well with the analytical solution and the experimental data.Finally, the model is applied to the simulation of interaction between waves and a submerged horizontal circular cylinder.The effects of the KC number and the cylinder depth on the wave forces are studied.     

Evalution of Application of p-y Curve Method in Offshore Engineering Foundation

- Based on the Mohr-Coulomb failure principle and Rankine's theory, the laterally loaded pile ultimate resistance formulas of sand and soft clay proposed by Reese and Matlock respectively are discussed in this paper. The authors put forward the modified ultimate resistance formulas on the basis of which the ultimate resistance formula is developed for horizontally loaded pile in multi-layer soil in consideration of the effect of the overburden soil pressure on the calculation of soil layer. It is significant to the correct application of the ultimate resistance formulas in API and ZCS Rules into offshore engineering.     

Determination of Shaft Capacity for Pile under Cyclic Axial Loading in Clay

For load-controlled and displacement-controlled test data of piles cyclically axially loaded in clay, the displacement conditions are suggested for determining the shaft capacity. According to the suggested displacement conditions, not only the results of shaft capacity from laboratory model piles are close to those from in-situ piles, but also the results of load-controlled tests are in satisfactory agreement with those of displacement-controlled tests. Moreover, based on the test data of laboratory model piles in combination with the test data published, the paper suggests the values of the normalized shaft capacity of piles under a variety of static and cyclic loading combinations.     

Nonlinear Dynamic Analysis of Flexible Marine-Risers

A nonlinear dynamic analysis model is estabilished on the basis of "lumped mass" approach, which takes the influence of the fluid flow within the pipe into consideration. Numerical results are compared with the published works, and the effects of internal fluid flow, internal pressure, dyanmics as well as the nonlinear characteristics on the behavior of flexible risers are discussed. From this work, some useful conclusions are drawn.     

试论我国海岸侵蚀信息系统的建立

本文通过对我国海岸侵蚀特点的分析,阐述了建立海岸侵蚀信息系统的必要性和基本方法,并给出了相应的结论。     

Experimental Investigation on Durability of Reinforced Concrete Beams in A Simulated Marine Environment

1. IntroductionConcrete is widely used for nearshore and offshore marine structures and bridges (Song et al.,2000; Wang and Song, 2004). Experience has shown that the durability of marine concrete structuresis generally good; however, some cases of serious deterioration also exist due to the lack of durability(Metha and Gerwick, 1982). Under marine conditions, concrete, especially concrete in the splashand tidal zone, is attacked, resulting in corrosion of reinforcing bars. Corrosion of rein…     

Trial and Numerical Analysis of Specimen Pipelay

Subsea pipelay has a relatively long history. In recent years, there has been a domestic need for the laying of large diameter thin wall pipes. A land-based trial for the large diameter thin wall specimen pipe is described in this paper. Re-gression analysis is performed for the trial data and the formula derived can express the trial data very well. Numerical analysis is adopted to compute various trial conditions. Then the numerical model is revised with the trial results, which are consistent with each other. After summarization of the results of trial and numerical analysis, the characteristics are described of the spatial configuration during the laying of the pipe and it is concluded that the maximum strain appears around the center of the raised pipeline. In the end, a reference Standard, which limits the maximum stress below the yield stress is provided.     

An Analytic-Numerical Solution of Wave Transformation

An analytic-numerical solution of wave transformation in shoaling water is presented in this paper. The analytical expression for wave heights along the wave rays is derived in consideration of the combined effect of water depth shoaling, the wave refraction and the sea bottom friction. The wave rays (orthogonals) are calculated by a fourth order Runge-Kutta algorithm and the wave crest lines are computed by an iteration procedure. The numerical results are compared with analytical solution for a special case of parallel- straight contour shore and field data, and comparisons show that the proposed mathematical model and computation method are very useful and convenient for engineering application.     

Transformation of Wave Energy Spectrum in Shallow Water

- Combined with irregular wave-maker, the growing process of Wave Energy Spectrum in shallow water can be studied in wind wave channel on different water depth conditions, and its transformation characteristics and rules can be obtained.     

海水养殖与生态环境关系的研究——Ⅰ.无机氮对浮游植物生长的影响

采用中尺度受控生态实验、小型混养实验和虾池取样测定,研究海水中无机氮、N/P比值和藻类光合作用速率的变化规律,分析了无机氮和溶解有机氮(DON)的相互转化,比较了钙质角毛藻对不同形式无机氮的吸收,探讨了人工养殖海水中无机氮对浮游植物生长的影响。