复合地基与天然地基在地震作用下附加沉降的数值分析

通过大型通用有限元程序ANSYS建立模型,研究了复合地基和天然地基在地震作用下的附加沉降,计算结果表明,采用复合地基技术,对减少附加沉降有很好的效果。同时对群桩复合地基不同桩位特点进行分析,表明群桩复合地基中桩附加沉降大于边、角桩。提出了附加沉降系数的概念及计算公式,可对复合地基的设计提供技术支持。     

IKONOS立体影像全数字摄影测量试验研究

介绍了IKONOS立体影像应用于测图试验的情况,并对成果进行了分析和评价。通过试验研究其对于基本空间数据获取的可行性;考查其经济效益;综合评定其对于工程用图成图的可适用性。     

旅游景观资源的分类及其归属

景观是一种现象,在自然界里普遍存在,往往构成旅游的主体资源。旅游景观可以是人工体或天、地、生的自然体亦或是人工或自然的综合体。地质景观是景观中的一个亚类,一部分可列入旅游景观而称为旅游地质景观。 景观与景观资源是两个不同的概念。景观资源与矿产资源一样具有自然和经济两种属性。 旅游资源具有寄寓特性。它不单独存在而是寄寓在各类资源之中,是各类资源属性的延伸和扩大。所被寄寓的学科是评价这一资源的基础。自然资源从总体来说不是无限的、持续的、稳定的。对某些景观出现变态、退化等现象,如从其认识到治理偏离基础学科会出现难以挽回的失误。 本文论述了旅游景观资源的性质与功能以及分类模式,特别是旅游地质景观的特点。      

Sound speed profiles in high spatiotemporal resolution using multigrid three-dimensional variational method: a coastal experiment off northern Shandong Peninsula

It is essential to acquire sound speed profiles (SSPs) in high-precision spatiotemporal resolution for undersea acoustic activities. However, conventional observation methods cannot obtain high-resolution SSPs. Besides, SSPs are complex and changeable in time and space, especially in coastal areas. We proposed a new space-time multigrid three-dimensional variational method with weak constraint term (referred to as STC-MG3DVar) to construct high-precision spatiotemporal resolution SSPs in coastal areas, in which sound velocity is defined as the analytical variable, and the Chen-Millero sound velocity empirical formula is introduced as a weak constraint term into the cost function of the STC-MG3DVar. The spatiotemporal correlation of sound velocity observations is taken into account in the STC-MG3DVar method, and the multi-scale information of sound velocity observations from long waves to short waves can be successively extracted. The weak constraint term can optimize sound velocity by the physical relationship between sound velocity and temperature-salinity to obtain more reasonable and accurate SSPs. To verify the accuracy of the STC-MG3DVar, SSPs observations and CTD observations (temperature observations, salinity observations) are obtained from field experiments in the northern coastal area of the Shandong Peninsula. The average root mean square error (RMSE) of the STC-MG3DVar-constructed SSPs is 0.132 m/s, and the STC-MG3DVar method can improve the SSPs construction accuracy over the space-time multigrid 3DVar without weak constraint term (ST-MG3DVar) by 10.14% and over the spatial multigrid 3DVar with weak constraint term (SC-MG3DVar) by 44.19%. With the advantage of the constraint term and the spatiotemporal correlation information, the proposed STC-MG3DVar method works better than the ST-MG3DVar and the SC-MG3DVar in constructing high-precision spatiotemporal resolution SSPs.

     

Recognition and Measurement of Marine Topography for Sounding Generalization in Digital Nautical Chart

Generalization is a comprehensive process. It is not simply a question of an algorithm, such as simplification, selection, displacement, and so on. Only after geometric shapes and topological properties have been understood fully, can a sound and automated generalization process be possible. This article proposes a new theoretical model for sounding generalization in digital nautical charts. First, with the aid of Delaunay triangulation, a tree structure is introduced for a hierarchical representation of the marine topography. Then, an analytical algorithm for the recognition and the measurement of the marine topography is developed through the use of the tree structure. Finally, all of the techniques mentioned above are integrated into a model for sounding generalization, of which results are illustrated with the aid of several examples.     

Crustal Structural and Tectonic Evolution and Oil Prospect Evaluation in the Songpan-Zoigê Block

1 Introduction The Songpan-Zoigê Block (SRB) lies in the east of the Qinghai-Tibet Plateau. It is a triangle block confined and surrounded by three structure belts: the east Kunlun-west Qinling belt (EK-WQLB) to the north, the Sichuan Basin to the southeast and the Garzê-Litang-Jinsha River belt to the southwest. This block is also the joint part of three tectonic domains: the North China, South China and Qinghai-Tibet domains (Huang and Chen, 1987). The development and evolutio…     

多波束测量技术与海洋测绘工序的调整

总结了NS到H-Cell的科学涵义,同时结合海洋测量、数据库和产品化技术的相互影响,考察了目前的海图产品测绘的工序,按照水深测量与摄影测量技术的特点,提出了陆地与海洋NS、H-Cell的差异。设计了一个海洋测绘的调整工序,不仅提高了海图产品化的实时性,而且扩大了海洋测绘产品的多样性。     

数字海图点群状特征的识别、量测与综合

空间分布特征的保持是点群自动综合的核心和难点所在,为此,本文定义了4个参量：分布范围、分布密度、分布中心和分布轴线,来描述点群目标的结构化信息。利用Delaunay三角网和Voronoi图两种模型,着重探讨了点群分布特征的识别和量测问题,并在识别与量测的基础上,通过Voronoi图的动态构建,给出了点群自动综合模型,通过实际岛群数据的检测,证明了模型的正确性与可行性。     

库车5.6级、拜城5.3级地震形变前兆异常

分析研究了 1999年 3月 15日库车 5.6级、6月 17日拜城 5.3级地震前新疆克孜尔水库形变站观测到的前兆异常。库车 5.6级地震前 ,第一形变站基线具有突变性 ,异常幅度达 2 80μm,水准异常为渐进式 ,幅度稍小 ,但异常持续时间较长。在此次地震前其它测站的 14条垂直、水平形变测线都有程度不同的异常显示 ,最大异常量级为 1.2× 10 -5,中期异常达 1年以上 ,短期异常持续约 10 0天 ,临震异常在震前 7～ 15天出现。拜城 5.3级地震前各测线也观测到了较明显的前兆异常 ,最大异常量级为 8.3× 10 -6,短期异常持续近两个月。     

基于ADS40无控条件的海岛礁地形测量方法研究

针对远离大陆的海岛礁地形测绘与高程基准转换困难的问题,基于ADS40航摄系统获取远离大陆的海岛礁区域遥感影像,按照GPS差分无地面控制点的空中三角测量模式实现海岛礁的地理定位,选择高精度的卫星测高模型实现海岛礁区域的高程基准转换。在某海域进行了ADS40测量作业与高程基准转换试验,结果表明,无地面控制点空中三角测量的平面精度达到0.587m;基于卫星测高模型进行垂直基准转换的精度与同步验潮水位观测法得到的高程传递精度相当。