Applied Mechanics and Materials Vols. 353-356

Abstract: A designed measuring device of soil interfacial shear stress is introduced in this paper. We used the device for measuring the shear stress between the soil interface, of which the moisture content was 30% and the clay content were 5%, 9%, 15%, 21%, 30% respectively. The results show that the shear strength of experimental soil and friction between the layers decreases with the clay content increasing when the moisture content is 30% and clay content is more than 15%, and the results increase with the clay content increasing when the clay content is less than15%. Based on the study of the laminar soil interfacial shear stress, it provides the basis for the future research of the laminar motion of the sediment and the deposition of the liquefied motion soil.

Abstract: During the two surveys at both spring and neap tides in wet (July-August 2008) season, measurements of flow, turbulence, suspended sediment concentration (SSC), fine-grained sediment particle mean diameter (Dm) were carried out over 26 h that covered two M₂ semidiurnal cycles in the middle north channel of the Yangtze estuary. The preliminary observations data show complex temporal and seasonal variation in estuarine flocculation of fine-grained sediment. In the high-turbidity and high-energy area of the Yangtze estuary, the flocculation processes indicate that the turbulence shear stress maybe the most important factor to the fine-grained sediment flocculation processes during the spring and neap tide cycle change. There exists a turning point of flocs Dm vs. turbulent shear stress. The neap tidal critical turbulent shear stress is around 0.1 Nm^-2, much smaller that the spring tidal data of about 0.5 Nm^-2.

Abstract: Three-dimensional model test in wave basin is launched to obtain the designed wave elements for the harbor, and the distribution of wave height in port and the overtopping on wharf surface in the project of all-purpose wharf in Jinghai district of Jieyang Harbor. The length scale of the physical model is 1:100. To compare the wave height and overtopping in different layout schemes under the same experimental condition, the optimal scheme is scheme 2 in which the wharf structure of 1 # berth is arranged in the east and the breakwater is extended about 580 meters. Meanwhile, the effect of navigation channel on wave transmission and wave condition in harbor is briefly discussed.

Abstract: The numerical simulation of air bubbles breakwater was presented in this paper. The two-phase fluid of water and air was assumed as a variable density fluid. The numerical models were developed by FLUENT in order to explore the air amount scale in the system of air bubbles breakwater . The impact of submerged pipe depth on the wave dissipating performance of air bubble breakwater was obtained, which illuminated that The submerged pipe depth D is deeper, the wave dissipating performance of air bubbles breakwater is better. Furthermore, the effect of air amount and the incident wave periods on the performance of the air bubbles breakwater was analyzed.

Abstract: Vortex-induced dynamic response is the most important issue influencing marine riser. This paper presents an investigation on the vortex-induced nonlinear dynamic response of marine riser subjected to combined waves,currents and platform movement. The in-line force was solved by Morison equation under combined waves,currents and platform movement while cross-flow force was solved by wake oscillator model. Updated Lagrangianmethod was used to solve the nonlinear problem.The governing equations were discretized by finite element method and solved by Newmark-β method in time domain. Influence of nonlinearity, comparisons of vortex-induced dynamic responses under different boundary conditions and different flow profiles were discussed.

Abstract: By taking the 3D Laplace equation as the basic governing equation, a mathematical model with respect to the interaction between linear waves and arbitrary 3D structures was founded. For the example of wave action with three cylinders, numerical results show that wave force F_x decrease and wave force F_y increase in each cylinder by incident wave direction from 0° to 60°; wave height on origin point increases with incident wave direction increasing for given layout and incident wave conditions.

Abstract: Based on the high precision terrain datas , high resolution FVCOM(Finite-Volume Coastal Ocean Model) numerical model was established to simulation for tide current and study three-dimensional dynamic characteristics of the south of Radiation shoal waters. Result show that transverse circulation was easy to produce in channel and groove. The vorticity and helicity computation method was applied in the area for the frist time. Transverse circulation and helical flow characteristics of typical sections were preliminary studied, and result show the quantitative evidence for the existence of the Spiral flow.Deep groove is not always appear double reverse spiral flow structure, it changes with the main flow velocity. Shoal grooves appear, a main spiral flow structure, and show great adaptability to the terrain, which is the reflection of the spiral flow to the terrain maintain mechanism .

Abstract: Dissolved Oxygen (DO) of sea waters is an important index to ecologic environment of sea. Multidisciplinary surveys were carried out in four seasons from August 2006 to December 2007 in Fujian and Zhejiang waters. Contents of DO in winter and spring were higher than those in summer and autumn. Except for winter, contents of DO show a decreasing trend from surface water to bottom. The overall horizontal distribution of DO In the shore is higher than that of in offshore,but the detailed distribution is different in different seasons. The influence of Physical oceanography processes such as coastal current of Fujian and Zhejiang ,coastal upwelling and the intrusion of open-sea current, on Distribution Characteristics of Dissolved Oxygen was discussed by analyzing hydrologic and meteorologic data. The main conclusions are as follows:The contents of DO is negative correlated with Seawater temperature and salinity. The contents of DO in the shore is high which is impacted by the Yangtze diluted water and coastal current of Fujian and Zhejiang: There are three main reasons why the contents of DO are low in part sea waters of the studied area, which are the intrusion of Taiwan warm current and kuroshio water, the coastal upwelling and the stratification of water.

Abstract: Suspended sediment concentration is important index of water quality, and assessment coefficient of water environment. Remote sensing technology can overcome the shortcomings of conventional methods, such as low speed, long period, and scarce temporal and spatial data distribution. Thus it is meaningful to introduce remote sensing technology to monitoring suspended sediment. In this paper, two TM/ETM+ images of the Yangtze estuary were utilized, and based on review of available domestic and overseas remote sensing data of suspended sediment, also combined with analysis on the 21 samples of synchronizing collection on April 28, 2009 and 3 samples of synchronizing collection on March 26, 2000 at the same time of satellite passing through respectively, the inversion model of satellite quantitative data was setup correlated to suspended sediment concentration. Then the classification diagram of sediment concentration in the surface water at the South Branch of the Yangtze Estuary was drawn. This study gets the following conclusions:(1) TM4 band reflection coefficient is more related to surface sediment concentration, the correlation coefficient is 0.884. (2)Through the regression analysis, the quantitative remote sensing model is established. By the mode, using satellite picture, sediment concentration distribution map in study area is obtained. (3)The diffusion law of suspended sediment, the range of high turbid water region and the estuarine sediment transportation were further discussed from monitoring data, and its characteristic phenomenon were observed and the cause was also explained.

Abstract: In order to improve concrete freezing-thawing resisting ability in Inner Mongolia region, adding air entraining agent is one effective measure. Because triterpenoid saponins air-entraining agent have a good applicability for local raw material, it makes concrete slump obvious increase with different water cement ratio, but the range ability first increases then decreases, the 3d, 7d and 28d compressive strength influence are the same to the slump influence, which can effectively improve concrete freezing-thawing resisting cycle times, and mixing with naphthalene series water reducing agent applies to mix small water cement concrete, and high strength grade.