由秦巴泥盆纪岩相古地理研究探讨古构造活动

秦巴地区位于华北地块与扬子地块两个相对稳定地质单元之间,处于南、北方的过渡地带。泥盆纪是秦巴地区由活动转向相对稳定的关键时期。现通过地层古生物、沉积相古地理、古地磁、古构造演化及化探等学科的研究,诸多资料均说明这一过渡地带的存在。一、对泥盆纪古地理环境的争议当前对秦巴地区泥盆纪所处的古地理环境尚有争议,有无深海、半深海环境存在是问题的关键所在。鉴于志留纪末期,秦巴地区的隆起和海退,已被众多的沉积间断和秦巴广大地区缺少泥盆统底部地层所证实,因而早泥盆世的浅水环境争议不大,主要分岐是在中晚泥盆世,其空间部位则集中于北秦岭。武汉地院的周正国认为,秦岭山阳地区上泥盆统存在形成半深海或深海环境的等深积岩;王鸿祯先生认为,山阳、柞水一带的中泥盆世“柞水系”和晚     

循环荷载下土石混合体力学特性野外试验研究

土石混合体是一种物理、力学性质非常复杂的不连续介质。以云南某高速公路土石混合体边坡为例,分别对选取的3个试验点进行了单调加载、循环加载一次及多次循环加载试验,获取了其相应的剪切位移-剪切应力关系曲线,并对其曲线特征进行分析研究。通过对试样三维滑动面的形态分析,指出由于土石混合体三维滑动面的不规则性,利用传统的二维计算方法难以得到较为准确的强度参数。基于三维极限平衡理论,提出了土石混合体水平推剪试样强度参数的三维数据计算方法。并利用该方法得到了研究区土石混合体的相应的强度参数及残余强度参数。     

基于逆向工程的三维复杂地质体精细建模及ADINA前处理在FLAC3D 建模中的应用

逆向工程技术作为一门新兴学科在复杂模型建模方面具有独特优势,并在许多领域得到了广泛的应用,在此基础上本文首次提出了基于逆向工程的三维复杂地质体精细建模技术,使得建立模型达到既可视又可算的目的。利用现行大型通用有限元仿真平台(ABAQUS,AD INA,ANSYS等)良好的网格划分功能且具有与CAD /CAM软件有着良好的接口这一优点,对模型进行网格划分,然后转换为FLAC3D能够接受的格式,从而克服了FLAC3D在前处理建模方面的不足。以AD INA为例对相应的接口程序开发过程进行了阐述,将上述技术方法应用于工程实例,取得了很好的效果。     

黄土湿陷性的微结构效应

土结构是一种物质状态,可以层次式的概念模型加以确定。从图象处理角度,提出了微结构定量研究的技术路线,确定了结构要素的量化方法。通过分形结构分析,探讨了天然结构和压力对黄土湿陷性的影响、水与土样之间的作用规律及其湿陷效应,提出了分形结构的湿陷性控制机理。     

Spatial patterns of vegetation and climate in the North China Plain during the Last Glacial Maximum and Holocene climatic optimum

Reconstructing the spatial patterns of regional climate and vegetation during specific intervals in the past is important for assessing the possible responses of the ecological environment under future global warming scenarios. In this study, we reconstructed the history of regional vegetation and climate based on six radiocarbon-dated pollen records from the North China Plain. Combining the results with existing pollen records, we reconstruct the paleoenvironment of the North China Plain during the Last Glacial Maximum(LGM) and the Holocene Climatic Optimum(HCO). The results show that changes in the regional vegetation since the LGM were primarily determined by climatic conditions, the geomorphic landscape and by human activity.During the LGM, the climate was cold and dry; mixed broadleaf-coniferous forest and deciduous-evergreen broadleaf forest developed in the southern mountains, and cold-resistant coniferous forest and mixed broadleaf-coniferous forest were present in the northern mountains. The forest cover was relatively low, with mesophytic and hygrophilous meadow occupying the southern part of the plain, and temperate grassland and desert steppe were distributed in the north; Chenopodiaceae-dominated halophytes grew on the exposed continental shelf of the Bohai Sea and Yellow Sea. During the HCO, the climate was warm and wet;deciduous broadleaf forest and deciduous-evergreen broadleaf forest, with subtropical species, developed in the southern mountains, and deciduous broadleaf forest with thermophilic species was present in northern mountains. Although the degree of forest cover was greater than during the LGM, the vegetation of the plain area was still dominated by herbs, while halophytes had migrated inland due to sea level rise. In addition, the expansion of human activities, especially the intensification of cultivation,had a significant influence on the natural vegetation. Our results provide data and a scientific basis for paleoclimate modelling and regional carbon cycle assessment in north China, with implications for predicting changes in the ecological environment under future global warming scenarios.     

利用远震接收函数研究湖北地区地壳结构

利用2014~2015年湖北数字地震台网30个子台记录的远震波形资料，用频率域反褶积方法提取接收函数，由H-Kappa、CCP叠加方法反演得到各台站下方地壳厚度、泊松比及剖面AA′。结果表明：1）湖北地区地壳厚度总体趋势是西厚东薄，鄂西北、西南地区地壳厚度在45~55 km左右，鄂东地区地壳厚度在30~35 km左右；2）湖北地区泊松比值总体变化不大（0.23~0.27），说明这一地区岩石可能以中度组分为主；3）AA′剖面中出现“楼梯状”Moho面，结合相关文献分析，在武当山地区下方地壳的榴辉岩发生相变，使得相变后的下地壳密度改变而发生拆沉作用，因此鄂西地区地壳厚度发生陡变。     

Coseismic Slip from the 6 October 2008, M w6.3 Damxung Earthquake, Tibetan Plateau, Constrained by InSAR Observations

Coseismic deformation fields of the 6 October 2008 M _w6.3 Damxung earthquake were obtained from interferometric synthetic aperture radar by using three descending and two ascending Envisat images. Significant coseismic surface deformation occurred within 20?km?×?20?km of the epicenter with a maximum displacement of ~0.3?m along the satellite line of sight. We model a linear elastic dislocation in a homogeneous half space and use a nonlinear constraint optimized algorithm to estimate the fault location, geometry and slip distribution. The results indicate a moment magnitude M _w6.3, and the earthquake is dominated by oblique normal and right-lateral slip with a maximum slip of 2.86?m at depth of 8?km. The rupture plane is about 15?km?×?14?km with strike S190°W and dip 55° to NW, located at a secondary fault of the Southeastern Piedmont of the Nyainqentanglha Mountains. Slip on normal faults in the Tibetan Plateau contributes to the rift evolution.     

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合成孔径雷达干涉测量原理与应用

合成孔径雷达（SAR）是一种微波相干成像方法，应用不同波段的雷达信号可以对地球表面不同的散射特性成像。合成孔径雷达干涉（InSAR）是将两个不同轨道位置或不同时间获得的复数SAR数据进行相位差分处理，从这些差分干涉数据中可以提取特别有用的信息，用于绘制地形图，测量诸如地震、火山、冰川运动等造成的地形变，研究植被覆盖特性、洋流等。介绍了InSAR的基本原理与应用，并对影响干涉结果的一些重要因素进行了分析。