现代黄河水下三角洲北部土体固结沉降特征及其对地形变化的贡献研究

The sediments of the modern Huanghe River subaqueous delta are easily to generate settlement and lead to topography change which is due to fast deposition rate, high void ratio, moisture content and compressibility. The sediment consolidation settlements and its contribution to the topography change in the northern modern Huanghe River subaqueous delta are studied based on drilling data, laboratory experiment results, and water depth measurements of different time. The results show that the final consolidation settlement of drill holes in the study area is between 1.17 and 3.21 m, and mean settlement of unit depth is between 2.30 and 5.30 cm/m based on the one-dimensional consolidation theory and Plaxis numerical model. The final consolidation settlement obtained by Plaxis numerical model is smaller than that obtained by the one-dimensional consolidation theory,and the difference is 3.4%–39.9% between the methods. The contribution of the consolidation settlement to the topographical change is at 20.2%–86.6%, and the study area can be divided into five different regions based on different contribution rates. In the erosion area, the actual erosion depth caused by hydrodynamics is lower than the changes of measured water depth, however, the actual deposition amount caused by hydrodynamics is much larger than the changes of water depth obtained by measured data in the equilibrium and deposition areas.     

考虑弹性核作用下的冲击地压形成机理模型试验

使用CCD相机搭建实验图像数据采集系统,采用花岗岩模拟坚硬顶底板、红砂岩模拟软岩层组合成岩层结构,近似还原顶板来压过程中软岩层的变形破坏过程,研究帮部"弹性核"对冲击地压至灾的影响机制。研究结果表明:(1)上覆顶板来压时,可将软岩层划分为塑性破坏区、弹性承压区、原岩应力区,弹性承压区易形成较大的弹性核。(2)软岩层变形能在弹性承压区大幅度积累,其积累过程是波动式上升的;在峰值荷载前,变形能积累和释放的频率加快;达到峰值荷载时,弹性承压区变形能存在明显的释放过程。(3)冲击地压发生时,塑性破坏区冲击并反作用于临近岩体使其短暂收缩。(4)冲击地压是一个渐进性的过程;一方面,由于水平约束的消失,弹性承压区的受力状态由水平方向受约束的压缩状转入单轴压缩态,导致其承载能力减弱;另一方面,承载区面积快速减小,导致软岩层承压区域承担的竖向荷载突增;两者共同作用导致冲击地压出现渐进性的冲击和破坏。     

论月球不对称的演化

月球形成初期有一个固体内核,表层是岩浆“海洋”重力分异,冷却固结形成月壳,由于同步自转,其一侧总是向着地球,在地球引力场作用下,使固体内核向地球一侧移动,月壳表层轻的物质向背地球一侧漂浮,所以月亮背地球一侧１５０公里,向地球一侧仅有６０公里,这种演化机制使大部分月海分布在向地球一侧。     

Photosynthesis-irradiance relationship of phytoplankton and primary production in the vicinity of Kuroshio warm core ring in spring

The light-saturated maximum value (P ^B _max) and initial slope (α) of the photosynthesis-irradiance (P-E) curve were examined in a warm streamer, a cold streamer and a warm core ring off the Sanriku area in the subarctic western North Pacific Ocean during an ADEOS/OCTS Sanriku field campaign in early May 1997. BothP ^B _max and α were within the ranges of temperate populations. A regional difference was apparent inP ^B _max: populations in the warm streamer tended to show higher value ranging between 1.92 and 4.74 mgC (mgChla)⁻¹h⁻¹ than those in the cold streamer and the warm core ring (1.35–2.87 mgC (mgChla)⁻¹h⁻¹). A depth variation was also observed in α in both the warm streamer and the warm core ring: shallow populations tended to have lower α than deep populations. The depth variations in bothP ^B _max and α resulted in a lower light intensity of the light saturation in a deeper population than that of a shallower one. These depth-related variations in the P-E parameters were likely a manifestation of “shade-adaptation” of photosynthesis. Photoinhibition was not observed over in situ surface light intensity varying below ca 1600 μmol photon m⁻²s⁻¹. Water-column primary productivity was biooptically estimated to be 233 to 949 mgC m⁻²d⁻¹ using vertical distributions of the P-E parameters, chlorophylla, phytoplankton light absorption and underwater irradiance. Applicability of surface data sets for estimation of water-column productivity is discussed.     

国内外岩芯数字化信息发布平台建设进展

岩芯数字化是以岩芯为对象,通过采用现代信息技术(表面图像扫描、物理参数扫描、化学参数扫描(高光谱矿物扫描、XRF岩芯扫描)、互联网技术等),开展岩芯信息提取、整合、研究、发布服务等,为地质工作者科学研究、找矿等开发利用提供实体和信息资源,本文通过梳理国内外岩芯数字化信息发布服务工作进展,介绍了各国岩芯数字化信息发布平台案例,总结对比了我国岩芯数字化信息建设存在的问题,提出了下一步制定岩芯数字化标准、搭建一个平台、加强岩芯多参数数字化的工作建议。     

海洋沉积地层多功能取样钻具研制

目前,海洋钻探取心主要采用提钻或绳索打捞的方式获取岩心。随着对取心质量和采取率要求越来越高,再加上海底沉积层变化多样,单一的取样器具已经不能满足当前的取样需要。为此,本文研制了一种海洋沉积地层多功能取样钻具,能够根据海底地层性质,开展低扰动、高品质的取样操作。通过海洋钻进取样试验表明,针对海底的淤泥、粘土及砂质地层,超前取样钻具、液压剪切取样钻具和半合管取样钻具能够有效获取海底的沉积层岩样,平均采取率为73.34%。研制的多功能取样钻具采用超前取样和液压压入取样技术,降低了对沉积物岩心的扰动,提升了岩心品质和采取率,为下一步的工程化应用奠定了基础。     

新区转型期的人口挑战与应对——以天津滨海新区核心区为例

天津滨海新区核心区正处于产业结构、城区职能、"港一城"关系的转型阶段与人口快速集聚时期.利用第四、第五次人口普查资料和2005年抽样资料,结合社会经济统计数据,详细分析了天津滨海新区核心区转型期的人口特征及趋势.结果表明,该区存在着人口吸纳能力不足、社会养老负担明显加重、行业和职业呈现低端化、资源环境的承栽能力较弱等问题,虽与区域的发展阶段、产业基础、自然本底相吻合,但严重制约了该地域的社会经济转型.为推动该区转型,亟需转变人口发展模式,通过借鉴浦东新区的经验教训,从就业与社会极化、"银发经济"、教育与创新、集约环保等方面提出应对措施.     

Sedimentological, geochemical and palaeontological evidence for a neoglacial cold event during the late Holocene in the continental shelf of the northern South Shetland Islands, West Antarctica

Two sediment cores obtained from the continental shelf of the northern South Shetland Islands, West Antarctica, consist of: an upper unit of silty mud, bioturbated by a sluggish current, and a lower unit of well-sorted, laminated silty mud, attributed to an intensified Polar Slope Current. Geochemical and accelerator mass spectrometry ¹⁴C analyses yielded evidence for a late Holocene increase in sea-ice extent and a decrease in phytoplankton productivity, inferred from a reduction in the total organic carbon content and higher C : N ratios, at approximately 330 years B.P., corresponding to the Little Ice Age. Prior to this, the shelf experienced warmer marine conditions, with greater phytoplankton productivity, inferred from a higher organic carbon content and C : N ratios in the lower unit. The reduced abundance of Weddell Sea ice-edge bloom species ( Chaetoceros resting spores, Fragilariopsis curta and Fragilariopsis cylindrus ) and stratified cold-water species ( Rhizosolenia antennata ) in the upper unit was largely caused by the colder climate. During the cold period, the glacial restriction between the Weddell Sea and the shelf of the northern South Shetland Islands apparently hindered the influx of ice-edge bloom species from the Weddell Sea into the core site. The relative increases in the abundance of Actinocyclus actinochilus and Navicula glaciei , indigenous to the coastal zone of the South Shetland Islands, probably reflects a reduction in the dilution of native species, resulting from the diminished influx of the ice-edge species from the Weddell Sea. We also document the recent reduction of sea-ice cover in the study area in response to recent warming along the Antarctic Peninsula.