Analysis of the experimental compressibility of deep water marine sediments from the Gulf of Guinea

This study strives to analyze the compressibility of deep water marine sediments originating from the Gulf of Guinea. Our approach is multi-scaled and, on the macroscopic level, based on two equations which link the overburden effective stress with the liquidity index, the Biarez & Favre equation on the one hand, and the Burland equation on the other hand (after calculation of the ICL expression as a function of the I_L parameter). On the local level, the evolution of the microstructures is analysed and compared with GoG remoulded clay. Two additional observation techniques have been used, the scanning electron microscope and the mercury intrusion porosimetry.     

Wave reflection in 3D conditions

Based on recent experiments carried out in wave basin on breakwaters with armour layer of rocks and cubes, this paper examines the dependence of the reflection coefficient on wave directional spreading and obliquity. Results suggest that long-crested and short-crested waves give similar reflection. The reflection coefficient is markedly dependent on the wave angle of incidence. The performance of formulae available in the literature is checked against the new dataset and a significant improvement is proposed by including the wave obliquity factor that appears in the traditional expression for the overtopping discharge.     

Wave interactions with multiple-row curtainwall-pile breakwaters

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.     

中国大陆动力学研究进展——纪念中国地球物理学会成立60周年

本文简要地回顾了中国大陆动力学研究发展的历史、特点和主要成果,存在的主要问题,提出相应的改进建议.(1)我国大陆动力学研究是从1926年李四光发表《地球表面形象变化之主因》一文开始的,他肯定大陆漂移说的革命意义和不足之处,提倡和坚持了用力学原理研究地壳运动和变形,主张用多学科方法,构造体系的观点对构造运动和变形进行概括,强调要从原理上探究地质作用的发生是否可行等等,这是中国的光荣传统之一.(2)当代大陆动力学的研究是以深部调查为基础,以岩石圈为研究对象,进行三维演化的探讨.提出它是以地质学、地球物理学,地球化学,大地测量学,地质力学和高温高压实验地质学理论知识为基础的综合性学科.是研究地球成矿作用、地震火山地质灾害发生机制的基础.这是当代地球科学发展的主要趋向,且日趋深入和扩大.(3)我国深部调查工作是1958~1962曾融生在柴达木盆地所作地震测深试验开始的.从上世纪80年代扩大了工作规模,并随着国际地学的发展而不断深入和扩大,先后工作在青藏高原,大别山变质岩带,秦岭造山,华南花岗岩区,以及南海新生边缘海盆等地区,现在又转向天山造山带和华北大陆地区（研究大陆减薄与裂解问题.此外,还结合全国地震带,成矿带进行工作.已获得了丰富的科学成果,引起国际地学界的重视.(4)工作的主要体会是：如,深部研究要以地壳上地幔为对象,并力求结合实际资源、环境科学问题的探讨,以利于深化认识;要坚持多学科综合应用,特别是加强构造动力学的分析,提高深部探测技术,处理方法和软件水平,重视深源包体采集和研究;大陆深钻应与综合调查紧密结合;要以我为主积极与外国合作,与国际接轨,不能盲目跟“风”.(5)提出我国大陆动力学研究存在“一少”、“二乱”、“三假”、“四霸”的现象,及其产生的根源作了分析,并提出改进的对策建议.当前更需要我们有 “志气”走出一条自己的路,创造一个好的学术“环境”.     

高频电磁波在不同目标体上反射图像特征研究

针对高频电磁波技术在北京勘察设计行业应用的空白,本次研究利用探地雷达技术对北京地区典型工程目标体进行了研究.针对不同的地下目标体对高频电磁波所反映出的不同反射特性,总结出一些图像特征规律.通过建立对各类雷达探测图像进行地质解释的理论依据和基础,本次研究对层状介质、地下管道、CFG桩、碎石夯扩桩、水泥土桩和洞穴等目标体的雷达图像特征进行了较系统的研究和总结,为今后日常的检测工作奠定了很好的基础.     

残差辨识模型在菏泽市区深层地下水水位预测中的应用

菏泽市区深层地下水由于长期大量开采,８０年代中期就已形成降落漏斗,且中心水位逐年下降,漏斗范围不断扩大。根据菏泽市区１９８７～１９９７年深层地下水动态监测资料,应用残差辨识预测模式对其水位作了短期预测,并对预测结果进行了后验差检验,预测精度较高。     

波动方程角度域共成像道集

针对基于波场深度递推的波动方程叠前深度偏移成像方法难以准确地给出如Kirchhoff积分叠前深度偏移成像方法的偏移距域共成像道集的不足,在分析研究现有的各种波动方程偏移成像共成像道集方法的基础上,利用波场外推的单平方根算子和波场的窗口Fourier框架展开与重构方法,提出一种局部角度域共成像道集方法——成像点处反射角共成像道集方法.把这种角度域共成像道集方法应用于国际标准的Marmousi模型数据和一条实际二维地震数据都取得了理想的结果.提出的波动方程反射角度域共成像道集方法可为进一步的叠前偏移数据振幅随角度变化分析和偏移速度分析工作提供基础.     

基于深度神经网络的海表盐度反演

海表盐度（Sea Surface Salinity,SSS）是研究海洋对全球气候影响的重要参量,欧洲航天局（European Space Agency,ESA）设计研发的SMOS(Soil Moisture and Ocean Salinity)是专用于探测海水盐度的卫星之一。受射频干扰（Radio Frequency Interference, RFI）等因素的影响,SMOS卫星盐度产品的精度难以达到预期效果。为了提高SMOS卫星海表盐度产品精度,本文提出一种基于深度神经网络的海表盐度反演算法。以太平洋中部海域（150°E～180°,5°～30°N）为研究区域,利用Argo浮标实测盐度数据为参考真值,将SMOS卫星L1C、L2级产品与Argo盐度数据进行时空匹配。并根据海洋遥感和辐射传输理论,选取亮温（Brightness Temperature,TB）、海表温度（Sea Surface Temperature,SST）、降雨率（Rain Rate,RR）、波高（Significant Wave Height,SWH）、纬向风速（Zonal Wind Speed,ZWS）、经向风速（...     

现代长江水下三角洲浅地层地震相特征

利用传统的地震相分析方法,分析总结现代长江水下三角洲浅地层地震剖面反射波的几何形态、内部反射结构、连续性、振幅等特征,形成对长江水下三角洲各典型地震相特征的认识,圈定相应的地震相范围,并结合钻孔资料,解释了长江口范围三角洲前积、浅海沉积、古河道等各沉积相的分布。结果表明,现代长江水下三角洲浅地层各地震相特征明显。典型的三角洲前积地震相主要分布在长江口外东北部,其余大部为典型浅海沉积地震相,且浅海地震相特征向口内逐渐变弱,表现为浅砂或淤泥型地震相,向口外逐渐有晚更新世基底地震相出露,并发育古河道地震相,此外,浅层气地震相嵌入区内各个地震相范围。     

南黄海西部某风电场区浅层气特征与分析

通过对南黄海西部某风电场区调查资料的分析,发现大量浅层气,主要表现为连续地层反射波发生间断,反射杂乱,部分地层反射波被屏蔽且延伸到深部地层中,局部地层反射波因声速异常导致下拉,反射高频衰减迅速,分辨率降低等。该区域内未发现断层,浅层气封存较好,推测为生物成因沼气,弥散浅层气埋深最浅约5 m,高压气囊顶部埋深最浅约272 m,地质浅孔钻遇高压气风险小。根据浅层气的特征,对其成因、压力和灾害进行了分析和探讨。