Wave interactions with multiple-row curtainwall-pile breakwaters     

Chang-Hwan Ji  Kyung-Duck Suh 《Coastal Engineering》2010

In this study, a mathematical model has been developed that can compute various hydrodynamic characteristics of a multiple-row curtainwall-pile breakwater. To examine the validity of the developed model, laboratory experiments have been conducted for double- and triple-row breakwaters with various combinations of drafts of curtain walls, porosities between piles, and distances between rows. Comparisons between measurement and prediction show that the mathematical model adequately reproduces most of the important features of the experimental results. As a whole, the transmission coefficient decreases with an increase in relative water depth, whereas the reflection coefficient, normalized run-up and force exhibit an opposite trend in their variations. With fixed values of the draft of the curtain wall and the porosity of lower perforated part of the first row of a double-row breakwater, as these values of the second row increase and decrease, respectively, the transmission coefficient decreases, as expected. On the other hand, their effects on wave reflection, run-up, and wave force change with the relative depth. As for the distance between the rows, the transmission coefficient becomes a maximum when it is about one half of the wave length, suggesting that this condition should be avoided to achieve the advantage of the breakwater in reducing wave transmission. It is shown that for prototype breakwaters, on an average, the transmission coefficient would be smaller than 0.3 for wave periods less than 6.0 s, and it would be about 0.45 even for the wave period of 9.0 s, although there would be a variation depending on the geometry of the breakwater. It is also shown that wave transmission is significantly reduced by multiple-row breakwaters compared with a single-row breakwater, while the difference between double-row and triple-row breakwaters is marginal. Finally, engineering monograms are provided for double-row breakwaters to be used in practical engineering applications of the breakwaters.  相似文献   

Simulation of snowstorm over the Yellow Sea using a mesoscale coupled model     

Ki-Young Heo  Kyung-Eak Kim  Kyung-Ja Ha  Kwang-Soon Park  Ki-Cheon Jun  Jae-Seol Shim  Young-Sang Suh 《Asia-Pacific Journal of Atmospheric Sciences》2010,46(4):437-452

This study aims to examine the favorable conditions for an ocean effect snowstorm across the Yellow Sea over the southwestern coast of Korea on 21 December 2005, using a coupled model with a Coupled Ocean/Atmosphere Mesoscale Prediction System as the atmospheric component and the Regional Ocean Modeling System as the oceanic component. Simulation of heavy snowfall event, which was 44.3 cm of snow accumulated in 24-hour, was performed to investigate the mesoscale structure, dynamics and development mechanisms in the snowstorm. As a result from 48-hour integration, the results of simulation showed that barotropic instability and turbulent heat fluxes played important roles in the formation of snowstorm. The enhanced surface diabatic heating was dominant in the latent heat flux, and eventually induced convective instability. An additional factor was the favorable condition of synoptic environment, accessing the cold air transport by the approach of the upper-level cold vortex over the warm ocean. Besides these factors, conditional symmetric instability (CSI) is a mechanism which can result in a heavy snowfall with sufficient moisture and upward vertical motion. A slantwise convection from the release of CSI could support a complex snowfall event with heavier than expected amounts. The result comparison between a coupled model and an uncoupled model supports that airsea coupling has an impact of decreasing of about 10% in a snowfall amount on the snowstorm.  相似文献   

Geotechnical and hydrogeological approaches towards conservation of the Muryong Royal Tomb in Korea   总被引：2，自引：0，他引：2  

Min-Ho Koo  Man-Cheol Suh 《Environmental Geology》2001,41(3-4):470-479

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Instability of an underground ancient tomb due to excavation and its relationship to the temperature and ground water     

Mancheol Suh  Min-Ho Koo  Suck-Won Choi  Insun Song 《Geotechnical and Geological Engineering》2004,22(2):269-283

In order to consider a counterplan to preserve an ancient royal tomb in Kongju, Korea, the deformation of the wall structure, the atmospheric temperature in the tomb, and the groundwater level have been monitored. The long-term measurement of biaxial tilting of the tomb walls revealed that the brick-built subsurface opening had been subjected to severe structural instability. The measured deformation of the tomb was consistent with the displacement of soil around the tomb calculated using a numerical analysis. The instability of the tomb structure is closely related to the rainy season as the deformations measured are several times that in the dry season. A sudden change of temperature inside the tomb exerted an influence on the deformation of the tomb structure as well. It is suggested that the excavation be restored for tourists, the quicklime layer for preventing groundwater infiltration is reinforced, and a constant temperature is kept inside the tomb. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

对黄海—东海研究区深部结构的一些新认识   总被引：16，自引：7，他引：16       下载免费PDF全文

郝天珧  徐亚  胥颐  Suh Mancheol  刘建华  戴明刚  李志伟 《地球物理学报》2006,49(2):458-468

综合地震层析成像与重磁数据的处理结果，选择26°N～36°N，120°E～130°E的范围作为研究区，讨论了黄、东海研究区的深部结构特点及其与周边各地质单元的相互关系，完成了研究区两条剖面的密度结构反演，认为东海陆架地区地壳厚度变化与大陆地区相比并不明显，显著减薄开始于冲绳海槽地区，中地壳消失；琉球岛弧处地壳厚度明显再度增加，特别是上地壳的厚度增加最大，推断其原因应与俯冲作用及俯冲带附近板块与地幔的运动速率之差有关.地球物理场“东西分带”是黄海—东海地区壳内结构从西向东变化的反映，但随着深度的增加，研究区的岩石层结构出现以近EW向为优势的构造格局.因此推断深部近EW向的异常是三叠纪时期南北板块碰撞、挤压所致，浅部的NE向条带异常是后期构造运动在岩石层较浅部位构造效应的反映.黄海—东海地区岩石层结构存在浅部与深部优势构造方向不协调的现象.层析成像结果证实了南黄海东缘断层的存在，还勾绘出绍兴—十万大山碰撞带为以40°左右的倾角向NW方向倾斜的高速带，另一条倾向基本相同的高速带则是南、北扬子块体结合带在深部的反映.  相似文献   

Mesostructural and microstructural evidences for a two stage tectono-metallogenetic model for the uranium deposit at Mika, Northeastern Nigeria: A research note   总被引：1，自引：0，他引：1  

C. E. Suh  S. S. Dada 《Natural Resources Research》1998,7(1):75-83

The Mika uranium deposit is of the Central Massif vein-type. The deposit consists of a series of subparallel veins, similar to Lilljuthatten deposit (Sweden), with variable ore grade. Two main structural trends occur within the vicinity of Mika namely: (1) vertical N160E-N180E or N-S normal fault trend in which the brecciated granite has been permeated and cemented by silica ribbons; (2) N130E trend associated with reddish brown hematitized siliceous breccias filling open fractures. The N130E trend is younger, and it is a local, passive shear trend developed at the bends of the N-S faults. On a microscopic scale, samples from the N-S trend are rich in crude cubic-tetragonal prismatic crystals of uraninite and/or pitchblende ores occurring in association with a low-temperature greenschist mineral assemblage of chlorite, epidote, and mica. Conversely, samples from the N130E trend show widespread kaolinitisation, goethite formation and layering reminiscent of groundwater activity at shallow depths near the earth’s surface. The main uranium mineral in this zone is yellowish autunite. The model proposed here envisages that the mineralization was related to two separate processes. A first mineralization episode developed simultaneous with the greenschist mineral assemblage, and a second episode was related to remobilization and subsequent mineral concentration in the passive N130E open fractures by groundwater to form autunite. Such a model has far reaching implications for exploration. Although the secondary minerals along the N130E fractures are more obvious in the field, the potentially economic primary mineral concentrations may be concealed at greater depth in the N-S structures.  相似文献   

Bimodal wave spectra in lower Chesapeake Bay, sea bed energetics and sediment transport during winter storms     

John D. Boon  Malcolm O. Green  Kyung Duck Suh 《Continental Shelf Research》1996,16(15):1965-1988

The transition zone separating estuarine environments from the coastal ocean is characterized not only by distinctive morphological and sedimentary trends but by unique hydrodynamic forces as well. Lower Chesapeake Bay, a large coastal estuary within the Mid-Atlantic Bight of the U.S. East Coast, experiences complex wave and current-induced forces produced during winter storms. Wave and current measurements made near Thimble Shoal Light over five winter seasons show that most storms simultaneously produce both ocean and bay-generated wave trains that appear as distinct bimodal peaks in directional spectra. Analysis of selected storm wave records reveal that lower-frequency ocean waves, although nominally lower in amplitude than higher-frequency bay waves, are roughly equivalent to bay waves in terms of energy expended on beds of fine- to medium-grained sand at either end of the Thimble Shoal Channel. Grain-friction energy dissipation estimates calculated for waves and currents suggest that waves provide more net energy capable of transporting bottom sediment than currents, although strong barotropic flows briefly encountered during a major storm on 13–14 March 1993, exceeded wave energy expended at the bed by almost an order of magnitude. From analyses of wave orbital velocity spectra, it is shown that dual wave trains characterized by differences in peak frequency and direction may assist each other through interactions that increase their combined contribution to frictional energy dissipation and inferred sediment transport at the bed.  相似文献   

黄海及其邻区深部结构特点与地质演化   总被引：14，自引：5，他引：14       下载免费PDF全文

郝天珧  刘建华  Suh Mancheol  CHOI Suckwon  阎晓蔚  刘振峰 《地球物理学报》2003,46(6):803-808

根据黄海及其周边地区的布格重力资料，通过多种方法处理，得到有关断裂的信息并求取了研究区的地壳厚度分布. 经过与地震层析成像结果、地质资料的对比和综合分析，认为朝鲜半岛西缘断裂带和济州岛南缘断裂带均为深大断裂，断裂带的两侧速度结构存在较大差异. 推断朝鲜半岛和南黄海分别属于不同的地质单元. 根据对岩石层结构的综合分析，认为中朝与扬子块体在黄海海域的接触关系是扬子块体推覆于中朝块体之上. 从目前的地震层析成像、重力异常、地壳厚度分布等结果来看，还不足以判断扬子与华南块体结合带在黄海海域中的准确位置.  相似文献   

The Mount Cameroon 1959 compound lava flow field: morphology, petrography and geochemistry     

Manga S. Njome  Cheo E. Suh  R. Stephen J. Sparks  Samuel N. Ayonghe  J. Godfrey Fitton 《Swiss Journal of Geoscience》2008,101(1):85-98

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Tectonic evolution of the Tombel graben basement, southwestern Cameroon     

M.S.Njome C.E.Suh 《《幕》》2005,28(1):37-41

Planar structures (foliations and fractures) around the Tombel graben (southwestern end of the Central African Shear zone system) have been investigated and analyzed with the aim of unraveling the tectonic evolution of the basement. The foliations show two major trends, an older N-S-trending gneissose layering of uncertain agereworked by a later Pan-African (600 + 50 Ma) NE-SW ductile trend that is contemporaneous with sinistral shearing and mylonitization. The brittle phase characterized by NW-SE-trending open and partially filled fractures is younger than the mylonitization event and although it has not been dated, it is suggested that the origin of these fractures is linked to the onset of volcanism along the Cameroon volcanic line-31 m.y. ago.The mylonitic foliation is recognized for the first time and supports a tectonic evolution model for the Tombel graben in which ductile non-coaxial deformation was succeeded by brittle failure.  相似文献