Origin and morphosedimentary evolution of fine-grained modern continental shelf deposits: the Gironde mud fields (Bay of Biscay, France)   总被引：1，自引：0，他引：1  

P. Lesueur  J. P. Tastet†  O. Weber† 《Sedimentology》2002,49(6):1299-1320

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上海地区钻孔灌注桩施工中若干问题探讨     

蔡鹤呜 《上海国土资源》1995,(3):34-38

文章对上海地区钻孔灌注桩施工中有关不同桩型的施工要求，循环泥浆标准等技术问题展开讨论。  相似文献   

开拓供水新领域施工天然滤床渗流井取水工程   总被引：3，自引：0，他引：3       下载免费PDF全文

陈台智  周志彰 《探矿工程》1995,(1):11-13

开拓天然滤床渗流井取水，根据江河流量不同，取水量达１￣５万ｍ＾３／ｄ或更大。与传统的地面钻水井、挖大井或直接取江河水净化的方法有本质的区别。取水技术是以岩土钻凿综合新技术为依托，从河床砂卵砂石层底部通过集水竖井、导井、江底隧硐（输水平巷）和钻进渗流井群取潜流水。与传统方法相比具有维护简介，利于后续延伸工程的特点。  相似文献   

渤海湾淤泥质海岸潮汐汊道的发育过程   总被引：9，自引：0，他引：9  

张忍顺 《地理学报》1995,50(6):506-513

本文以黄河三角洲沿岸为例，论述淤泥质海岸上潮汐汊道的发育过程。研究表明，淤泥质海岸潮汐汊道与废弃河口深化化有密切关系。它的外侧海岸是在高海面时形成并被现代动力过程所切割的贝壳砂堤或砂堤。  相似文献   

高速黄土滑坡的一种机理——饱和黄土蠕动液化   总被引：13，自引：0，他引：13  

王家鼎 《地质论评》1992,38(6)

本文提出了高速黄土滑坡的一种机理——饱和黄土蠕动液化。文中列举了甘肃地区饱和黄土蠕动液化造成高速滑坡的实例,并从饱和黄土受力前后的应力条件及土体结构内部强度的变化分析了饱和黄土液化的机理。通过现场及室内试验得出剪切强度、剪切速度、饱和度及其它影响因素对液化程度的重要影响。提出了饱和黄土蠕、滑动液化导致高速滑坡的过程。最后,还讨论了高速滑坡及泥流的速度问题。  相似文献   

跨海桥基海上大口径钻孔施工技术          下载免费PDF全文

顾元威 《探矿工程》1994,(5):5-7

青岛女姑山跨海桥墩基础，采用大口径海上钻孔灌注桩施工，结合工程实践，分析了海潮对地压的影响与钢护筒埋设最佳值；探讨了海上施工泥浆循环系统的合理布设；海水泥浆的配制维护及钻孔护壁等问题。  相似文献   

基于纵波地震和四分量地震的弹性波阻抗反演   总被引：3，自引：0，他引：3  

张树林  张志斌 《海洋地质与第四纪地质》2007,27(5):51-56

为了更好地揭示崖13-1气田的泥岩夹层及剩余气分布,提高采收率,尝试了基于纵波地震和四分量地震的弹性波阻抗反演。利用常规纵波地震资料对崖13-1气田气层进行了多角度同时反演;利用四分量地震资料进行了纵波和转换横波波阻抗反演。基于常规纵波地震资料的弹性波阻抗反演剖面的分辨率较高,气层纵波波阻抗与盖层的纵波波阻抗差异大于横波,但横波波阻抗分辨率比纵波波阻抗高,对气层细节反映得更清楚。利用弹性波阻抗反演结果可以较好地发现剩余气、泥岩夹层及气水界面。转换横波地震资料的分辨率较低,基于四分量地震资料的弹性波阻抗反演的分辨率也比较低。  相似文献   

Dioxin compounds in the deep-sea rose shrimp Aristeus antennatus (Risso, 1816) throughout the Mediterranean Sea   总被引：1，自引：0，他引：1  

Guiomar Rotllant  Esteban Abad  Francisco Sard  Manuela balos  Joan B. Company  Josep Rivera 《Deep Sea Research Part I: Oceanographic Research Papers》2006,53(12):1895-1906

Polychlorodibenzo-p-dioxins (PCDDs) and polychlorodibenzofurans (PCDFs) are among the more toxic anthropogenic contaminants. They are fat-soluble and accumulate in animal tissues. Exposure to PCDD/Fs can cause several endocrine, reproductive and developmental problems in animals, including human beings. Several studies have demonstrated that fish and invertebrates living in association with sediments are exposed to and accumulate contaminants, but to date there have been no studies of PCDD/Fs contamination in deep-sea regions. Specimens of Aristeus antennatus (Risso, 1816) were collected from depths of 600–2500 m at different points in the Mediterranean Sea, from the western basin off the coast of Barcelona to the central basin off the Peloponnesian Peninsula, with otter trawl gear. Amounts of PCDD/Fs were measured in different animal tissues by high resolution gas chromatography coupled to high resolution mass spectrometry (HRGC–HRMS). This is the first study to report the presence of PCDD/Fs in deep-sea organisms dwelling at depths below 600 m. A. antennatus presented levels of PCDD/Fs of the same order of magnitude, or slightly higher, as those found in shallow-water species (Melicertus kerathurus) with respect to land-generated contamination. This highlights the widespread distribution of these pollutants and the potential threat posed to the biodiversity of fragile and vulnerable ecosystems such as the deep-sea. PCDD/F levels detected in the edible parts (muscle) of the commercial shrimp A. antennatus were clearly below the toxic limit value established by European legislation. Levels followed the trend muscle<ovary<hepatopancreas, according to the lipid content of the organs in question. The specific profile of toxic PCDD/F congeners in the studied Penaeid shrimp specimens was characterized mainly by octachlorodibenzo-p-dioxin (OCDD), 2,3,7,8-tetrachlorodibenzofuran (TCDF) and 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) congeners. Moreover, non 2,3,7,8-substituted congeners bioaccumulated in this species, as observed in shallow-water crustaceans. PCDD/Fs were found in the shrimp A. antennatus throughout the Mediterranean Sea. Total PCDD/Fs burdens were higher in shrimps caught in the western Mediterranean than in those caught at eastern Mediterranean sites. There was a tendency for higher levels of PCDD/F contamination in samples obtained from deeper (2500 m) than from shallower sites (600 m).  相似文献   

Deep-sea Polymetallic Nodule Mining: Challenges Ahead for Technologists and Environmentalists     

Anil B. Valsangkar 《Marine Georesources & Geotechnology》2003,21(2):81-91

Although, offshore mining for mineral wealth is not required at present, it may be the only alternative in the future due to the continuous growing demand for certain metals that have no or limited land deposits. Risk involved in deep-sea mining is not less than that in space missions. Limited groups of mining engineers and environmental scientists are conducting studies that influence the development of mining systems and subsystems for collection, screening, lifting, and transportation of deep-sea minerals. Accepting this challenge more than 20 years ago, the National Institute of Oceanography, Goa, started surveys and exploration for polymetallic nodules in the Indian Ocean and was the first to receive "Pioneer Status" recognition from the United Nations. Experiments have also been conducted to study the potential impacts of deep-seabed mining.  相似文献   

Association among active seafloor deformation, mound formation, and gas hydrate growth and accumulation within the seafloor of the Santa Monica Basin, offshore California   总被引：1，自引：0，他引：1  

Charles K. Paull  William R. Normark  William Ussler III  David W. Caress  Rendy Keaten 《Marine Geology》2008,250(3-4):258-275

Seafloor blister-like mounds, methane migration and gas hydrate formation were investigated through detailed seafloor surveys in Santa Monica Basin, offshore of Los Angeles, California. Two distinct deep-water (≥ 800 m water depth) topographic mounds were surveyed using an autonomous underwater vehicle (carrying a multibeam sonar and a chirp sub-bottom profiler) and one of these was explored with the remotely operated vehicle Tiburon. The mounds are > 10 m high and > 100 m wide dome-shaped bathymetric features. These mounds protrude from crests of broad anticlines (~ 20 m high and 1 to 3 km long) formed within latest Quaternary-aged seafloor sediment associated with compression between lateral offsets in regional faults. No allochthonous sediments were observed on the mounds, except slumped material off the steep slopes of the mounds. Continuous streams of methane gas bubbles emanate from the crest of the northeastern mound, and extensive methane-derived authigenic carbonate pavements and chemosynthetic communities mantle the mound surface. The large local vertical displacements needed to produce these mounds suggests a corresponding net mass accumulation has occurred within the immediate subsurface. Formation and accumulation of pure gas hydrate lenses in the subsurface is proposed as a mechanism to blister the seafloor and form these mounds.  相似文献