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软土作为一种不良土体,在黄河三角洲分布比较广泛,其工程特性一般表现为含水量高、强度低、压缩性大以及渗透性低等,易发生不良工程地质问题。黄河三角洲北部区域的河口区,软土的工程特性及空间分布目前尚未有系统分析研究。基于最新的较系统的工程地质钻孔数据资料,对河口区软土的工程地质特性参数进行了统计分析,研究了软土物理力学性质各指标的概率分布模型及参数间的相关性,就黄河三角洲地区软土的成因、厚度、埋藏条件、空间分布规律进行了分析总结,并对其主要工程地质问题及措施提出了建议。黄河三角洲北部河口地区的软土具有典型的软土特征:高含水量、高压缩性、低抗剪强度等,其软土的物理力学性质指标变异系数较小,概率分布基本符合正态分布,研究区85%的面积范围内发育软土层,软土层由近饱和或饱和的黏性土、淤泥及淤泥质粉土组成,属滨海相与三角洲相软土。该地区地基处理宜采用桩基法、排淤换填法、堆载预压法、电化学加固法等方法。 相似文献
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末次冰期以来巽他陆架的演变及其对南沙群岛海区古环境的影响 总被引：3，自引：1，他引：3
通过对南沙群岛海区NS94－93柱样磁组构，矿物成分分析，结合^14C测年，分析了末次冰盛期巽他陆架出露成陆及其后巽他陆架被海水淹没后南沙群岛海区沉积环境的变化，认为巽他陆架在13.2kaB.P。时开始被海水淹没，约经历600a左右趋于稳定，在末次冰期，南沙群岛海区水体封闭，沉积物以陆源物质为主，碳酸盐含量低，13.2-10kaB.P，沉积物以陆源物质为主，碳酸盐含量逐渐增加，至10kaB.P.南沙群岛海区进入全新世，水体交换条件得到较大改善，沉积物中生源物质显著上升，陆源物质明显减少，碳酸盐含量一直维持在较高水平。 相似文献
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南黄海油气资源区粘性土物理力学性质及微结构特征 总被引：1，自引：0，他引：1
用土质学的显微结构理论和技术方法,研究了南黄海油气资源区粘性土微结构特征。结合原状样物理力学性质参数,研究颗粒接触、堆垒、孔隙等现象与物理力学性质之间的关系。研究结果表明,沉积物主要为粘质粉土、淤泥质粉质粘土和淤泥等粘性土,其微结构类型有粒状链接微结构、蜂窝状微结构和疏松基质状微结构3种,其中淤泥类土主要为蜂窝状微结构和疏松基质状微结构,结构疏松,孔隙度较大,含水率很高,强度低,压缩性高。粘质粉土为粒状链接微结构．含水率较低,孔隙度相对淤泥类土较小,抗剪强度比淤泥类土略高,压缩性较高。该区粘性土为不理想工程地基土,工程施工时应采取相应措施避开或对其进行改良。 相似文献
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根据莱州湾沉积物的实验室分析资料,从物理性质和力学性质特征对海底沉积物的工程地质特征进行了综合研究,结果显示:研究区沉积物主要为淤泥质黏土,其次为淤泥、黏土、粉土,另含有极少量的粉砂,整体呈现为含水量低、天然密度大、孔隙比小、可塑性低、压缩性低、剪切强度高、贯入阻力大。从海底地形、物质来源、水动力特征、物质组成等方面对沉积物的工程特性进行了成因分析。莱州湾地势平坦,水体与外海交换能力差,沉积物的分布受地形和水动力特征的影响显著,淤泥主要出现于黄河入海口南北侧海域,黏土、粉土主要出现于莱州浅滩附近海域,粉砂分布于刁龙咀北部近岸海域,其他区域以淤泥质黏土分布为主。莱州湾沉积物主要来源于黄河携带的黄土高原物质,碳酸盐含量高,黏粒和亲水性黏土矿物含量较低,沉积物主要以胶结物和粉粒级碎屑的形式存在,导致湾内沉积物含水量低、天然密度大、塑性低、强度高。 相似文献
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《海洋湖沼通报》2017,(4)
基于海南岛泻湖分布众多、泻湖资源丰富,目前大部分泻湖处于退化状态,且未见有相关文献对海南岛泻湖资源进行详细系统的介绍与总结,本文通过对海南东寨港、东水港、花场湾、清澜港、小海、老爷海、博鳌泻湖、三亚河、青梅港、黎安港、新村港、铁炉港及新英湾等泻湖的地理分布、面积、资源类型等方面进行描述,从人类活动、陆源污染、海洋工程及自然演变等因素对泻湖的影响进行了分析,阐述了泻湖目前所面临的威胁及破坏,提出了对泻湖进行整治规划、持续开发利用、加强法制监督及提高民众泻湖资源保护意识等方面的保护与可持续利用建议,为海南岛泻湖资源的保护与可持续利用提供基础数据与理论参考。 相似文献
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天然气水合物作为一种新型的清洁能源,其形成需要稳定的有机质供应。南海北部神狐海域为天然气水合物成藏的有利区域,2017年中国地质调查局在神狐海域水合物试采获得突破性成功。为了进一步了解古环境和古生产率对形成水合物有机质供应的影响,对南海北部神狐海域水合物钻探区SH3站位180～215mbsf(meters below the sea floor)层位,尤其是水合物主要赋存层位190～200mbsf的古环境、古生产率以及陆源碎屑物质的地球化学指标进行分析研究。研究表明水合物主要赋存层位陆源碎屑物质(TDM)输入增加,较高的陆源碎屑物质输入和次氧化的沉积环境共同造就了比较好的有机质的外部保存条件;同时较强的水动力条件,有利于藻类生物的繁殖,因此,生物成因有机质比较丰富,再加上神狐海域有比较良好的热解气的形成条件,这3个层面共同保证了神狐海域具有比较充足的有机质供应。 相似文献
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通过对台湾东北部古海湾及周边356个海底表层沉积样品的粒度分析及碎屑矿物分析,揭示了古海湾及周边陆架自末次盛冰期以来的沉积环境演变特征,并分析了古海湾的成因。结果表明,该古海湾及周边海域沉积环境的演变可划分为3个阶段:(1)末次盛冰期,浊流、滑坡事件在海湾边缘及陆架边缘频繁发生,可携带大量的陆源碎屑物质输运至古海湾内(B-3),下蚀其海床及下伏地层,并塑造了作为浊流通道的两个砾石条带,在B-3内部保留分选差、改造弱的沉积物。在此期间,潮流、波浪和跨陆架流在东亚冬季风的影响下严重侵蚀B-3的湾口及湾缘,并沉积大量的砂、石英及低含量的生物碎屑物质,石英/长石比值也较高;(2)末次冰消期,随着海平面的阶段性上升,古海岸线向陆大幅迁移,导致浊流强度减弱,潮流逐渐成为陆架区主要的作用营力,相关的潮流底应力可改造陆架沉积物,此时期,西部陆架含砾砂-砾质砂区(B-1)和北部陆架含砾砂-含砾泥质砂区(B-2)的地势差异及其所影响的水平海侵速度和潮波强度的差异是造就两者沉积组分、类型、石英、长石、岩屑和生物碎屑的含量及石英/长石比值差异的主因;(3)高水位时期,黑潮强度在本区增强,除侵蚀B-1底床,黑潮底层流也对B区的浅水地带进行冲刷,加之台湾暖流及沿岸流、长江冲淡水对该区的影响较小,使得B区细粒沉积物质含量较低,A区(北部陆架含砾泥质砂沉积区)细粒沉积广布,除与弱潮流作用相关外,弱的底层流的影响也是原因之一,同时来自台湾暖流可能携带部分细粒沉积物在此卸载。对于古海湾的成因而言,末次盛冰期频繁的浊流是将前更新世时期受湾内断裂作用而形成的半地堑地貌的海湾雏形进一步塑造成深凹地貌的主因,它进一步加剧了其深凹的地貌,在后期的冰消期和高水位时期,潮波系统及黑潮逐渐强盛,阻止了细粒沉积物的输入,保留了古海湾的深凹地貌。 相似文献
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黄渤海沿岸海湾—溺谷型潮汐汊道的地貌结构 总被引：4，自引：0，他引：4
本文以丁字湾等基岩海湾为例，论述了黄渤海沿岸海湾－溺谷型潮汐汊道的地貌结构，尤其着重于口门段深槽及涨、落潮三角洲。认为涨、落潮三角洲的发育状况与入湾河流的供沙量、纳潮水域容量、波浪作用、潮差以及口外海域的开阔程度有关；泻湖型潮汐汊道的落潮三角洲的典型模式可以应用于海湾－溺谷型潮汐汊道，但涨潮三角洲因受基岩海湾的复杂岸线的限制而不能充分发育。本文还讨论了海湾型潮汐汊道与半开敞海湾在动力和形态中的差异 相似文献
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Jiang Kaihui Yao Minglun Lecturer Tianjin University Tianjin Professor Tianjin University Tianjin 《中国海洋工程》1994,(1)
-This paper presents the research results of dynamic pore water pressure and the characteristics of dynamic deformation of saturated soft clay and the factors affecting the dynamic pore water pressure and dynamic deformation. Dynamic triaxial compression tests are carried out and the soil samples used in the tests are remoulded clay from the seabed of the Bohai Bay. The paper also deals with the dynamic deformation mechanism of saturated soft clay foundation without drain. A calculation model for permanent dynamic deformation of saturated soft clay foundation has been established. 相似文献
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介绍了广州港新沙港区板桩码头主要内力计算方法及常用软件,结合设计过程、工程地质情况、现场实际施工情况,着重从受力合理性、施工便利性、节省造价方面,对提出的钢板桩方案、钢管板桩方案进行比较分析,确定了钢管板桩结构更合理,并对优势进行总结。研究表明相对于钢板桩结构,钢管板桩结构在抗弯、抗变形、拉杆拉力和锚碇墙稳定性、对复杂地基(软弱土层较厚、岩层标高较高的地基)适应性、兼顾桩基基础、施工速度等方面更具备优势,且钢管板桩结构可更好的适应码头的大型化和深水化发展,在类似工程设计中可优先采用钢管板桩结构。 相似文献
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Integrated studies on the hydrochemistry and water column rates of microbial processes in the eastern sector of the Black Sea along a standard 100-miles transect off Gelendzhik from the coast to the central part of the sea at water depths of 100–2170 m show that a series of warm winters and the absence of intense convective winter mixing resulted in a relatively low content of suspended particulate matter (SPM), particulate organic carbon (POC), and nutrients in the water column in March 2009. The relatively high SPM concentrations and the presence of isotopically light POC at the offshore station are indicative of the supply of terrigenous material from land and low contributions of phytoplanktonic organic matter to the composition of SPM. This may explain the low rates of biogeochemical processes in the water column near the coast. The surface layer at deep-water stations is dominated by isotopically heavy phytoplanktonic organic matter. This suggests that the supply of terrigenous material from land was insufficient in offshore deep-water areas. Therefore, warm winters and insufficient nutrient supply do not prevent photosynthesis in the photic layer of the deep-water zone, which generates organic substrates for heterotrophic aquatic communities. The results of isotopic analysis of POC, measurements of the rates biogeochemical processes, and the hydrochemical characteristics of the water column can be used to determine the nature and seasonal variability of the POC composition. 相似文献
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《Deep Sea Research Part II: Topical Studies in Oceanography》1999,46(10):2221-2247
Sedimentological and geochemical investigations of 45 box cores collected in various morphological settings of the Cap-Ferret Canyon (Bay of Biscay) are presented to document accurately present-day sedimentary processes on the eastern Atlantic continental slope. The magnitude and variations through time and space of the canyon's channelling or sinking effect on fine-grained particles behaviour in comparison with sediment flux across the continental margin was particularly considered and discussed:1. All the parameters (grain-size, carbonate and water content, major and trace elements), measured both in surface sediment and downcore, demonstrate that the characteristics at the sediment interface vary with water depth and with the morphological setting.2. Surface sediment is generally coarser-grained, more terrigenous and deposited at higher rate in the canyon than outside. The terrigenous particle supply must be preferentially directed and trapped within the canyon's depression due to present-day dynamic conditions.3. The downcore gradients reflected in grain-size variations yield information on settling processes. The coarse-grained population has the characteristics of a winnowed sediment similar to those on the outer shelf, while the fine-grained population has grain-size spectra very similar to the present-day fine-grained suspensions.4. The carbonate particles are partly derived from direct pelagic production (distinct grain-size distribution) and, like terrigenous grains, are partly reworked (similar downslope decrease in the coarse grained fraction). The relatively low CaCO3 content observed in the canyon, and its downward increase up to values observed at shallower depths, may result from a channelling of terrigenous suspensions within the canyon.5. At the present high sea-level stand, the canyon should become a trap for sediments without much gravity remobilisation, as indicated by a lack of sedimentary structures in box cores. However, a simple increase in sediment trapping can hardly account for the downcore gradients observed in the box cores. These trends, which are observed on other continental margins (Monaco et al., 1993, Journées spécialisées de la Soc. Géol. France: Géosciences Marines, 16–17 December 1994, Abstract p. 83.), indicate a probable increase in terrigenous supplies and/or in settling energy. 相似文献
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Lin HJ Dai XX Shao KT Su HM Lo WT Hsieh HL Fang LS Hung JJ 《Marine environmental research》2006,62(1):61-82
Tapong Bay, a eutrophic and poorly flushed tropical lagoon, supports intensive oyster culture. Using the Ecopath approach and network analysis, a mass-balanced trophic model was constructed to analyze the structure and matter flows within the food web. The lagoon model is comprised of 18 compartments with the highest trophic level of 3.2 for piscivorous fish. The high pedigree index (0.82) reveals the model to be of high quality. The most-prominent living compartment in terms of matter flow and biomass in the lagoon is cultured oysters and bivalves, respectively. The mixed trophic impacts indicate that phytoplankton and periphyton are the most-influential living compartments in the lagoon. Comparative analyses with the eutrophic and well-flushed Chiku Lagoon and non-eutrophic tropical lagoons show that high nutrient loadings might stimulate the growth and accumulation of phytoplankton and periphyton and therefore support high fishery yields. However, net primary production, total biomass, fishery yields per unit area, and mean transfer efficiency of Tapong Bay were remarkably lower than those of Chiku Lagoon. The lower transfer efficiency likely results from the low mortality of cultured oysters and invasive bivalves from predation or the lower density of benthic feeders constrained by the hypoxic bottom water as a result of poor flushing. This might therefore result in a great proportion of flows to detritus. However, the hypoxic bottom water might further reduce the recycling of the entering detritus back into the food web. In contrast to many estuaries and tropical lagoons, poor flushing of this eutrophic tropical lagoon might induce a shift from detritivory to herbivory in the food web. 相似文献
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海岸带工程地质环境的稳定性对于海洋工程的建设安全和沿海经济繁荣十分重要。在胶州湾海域已有地质、水文等数据的基础上,对胶州湾海底工程环境适宜性进行了分区。通过无监督机器学习的谱聚类算法,构建了胶州湾海底工程环境适宜性综合评价模型。结果表明,胶州湾整体工程环境适宜性趋势为北高南低,从北向南依次可分为适宜性高、适宜性较高、适宜性较低和适宜性低四个区域。相关性分析表明,影响胶州湾海域海底工程适宜性的因素从高到低依次为冲淤分布、沉积物类型、坡度、第四系沉积物厚度、水深、海流流速、断裂分布。本研究可为胶州湾工程环境和地质灾害预防提供参考,有助于海洋工程环境稳定和经济安全保障。 相似文献
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姑合工程实践，介绍快速“高真空击密法”软地基处理方法的施工原理、施工工艺及质量控制等，并简单阐述“高真空击密法”在进行软地基处理中的优点。 相似文献
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Based on balance calculations with the use of a spatially detailed mathematical model for transport and sedimentation of the particulate matter adjusted to the conditions of the Sea of Azov, particular spatiotemporal features of the terrigenous sedimentation in the second half of the 20th century are recognized. The general tendency for the deceleration of the accumulation of terrigenous sediments and for the decrease in the areas with a negative balance of the terrigenous matter is related to the 2.5-fold fall in the volumes of the matter supplied from land. During the period considered, the intensity of the sedimentation decreased from 1000 to 400 g/m2/year. The accumulation of terrigenous sediments proceeds in the regions where the sources of the matter supply are concentrated and where features of the bottom morphology and hydrodynamical activity are favorable for the sedimentation: in Taganrog and Temryuk bays. In the central part of the sea, the intensity of the sedimentation comprises a value of about 300 g/m2/year. In Taganrog Bay and in the sea proper, areas with a negative balance of terrigenous sedimentary matter increased up to 30%. 相似文献
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辽东半岛东部庄河海域分布有大量的人类工程活动设施,研究其工程地质特征和开发适宜性有助于提升海洋工程开发的安全和效率。利用海洋高精度地球物理调查、海底沉积物表层取样和历史工程地质数据收集等方法获取的各类调查数据,对庄河海域海岸带工程地质特征进行了系统分析。调查资料分析结果表明,研究区水深在11.5～15.6 m、坡度较小、海底地形较为平坦、存在4个连续声学反射界面;海底存在软弱土层、埋藏古洼地和埋藏古河道等不良地质因素。表层沉积物液塑限性质测试结果表明,研究区海底沉积物较为稳定,不需考虑软土的震陷问题。综合分析研究区各类地质影响因素,认为研究区各类环境指标较为稳定,适宜开展海洋工程开发活动,但是具体施工时需要重点考虑探测到的各类不良地质因素。 相似文献