复杂地质体离散化三维网格模型建模方法探讨——以面向FLAC~(3D)软件的建模为例

在地学相关的数值模拟工作中,因地质体的复杂和数值模拟软件的功能制约,使建立地质体的离散化网格模型成为一个难点。文章介绍了综合应用AutoCAD和ANSYS软件建立复杂地质体网格模型的方法,该网格模型用于在FLAC~(3D)软件中进行数值模拟计算。通过建模对比实验和分析认为,多段线具有较好的数据交互能力,面域对不同的线型兼容性好,以造面域的方法闭合岩性单元报错少,基于多段线面域的网格模型能很好地满足复杂地质体的建模需求,基于样条曲线面域的网格模型适用于形态简单的地质体建模。建模软件的综合运用,可建立复杂地质体网格模型,为成矿及工程地质领域的数值模拟提供有力的支持。     

Field Modeling Method for Identifying Urban Sphere of Influence： A Case Study on Central China

With rapid development of urbanization and regional interaction and interdependence, regional urban agglomeration planning becomes more and more important in China, in order to promote integrated development of various cities with close interrelationship. However, it is still arguable academically on how to define the boundary or which cities to be included for the urban agglomeration of a region. This paper aims to shed lights on how to identify urban spheres of influence scientifically by introducing field modeling method and by practicing a case study on 168 cities in Central China. In our field modeling method, the influence intensities of cities were measured by a comprehensive index and urban spheres of influence were represented spatially by field intensity. Then, their classification and spatial distribution characteristics of study area in 2007 were identified and explored by using GIS and statistical methods. The result showed that: 1) Wuhan is the absolute dominant city in Central China; 2) the provincial capital cities dominate their own provinces and there are no other lower grade agglomeration centers; and 3) the basic types of organization form of urban sphere of influence are single-polar type, agglomeration type, close-related group type and loose-related group type.     

A GIS-based modeling approach for fast assessment of soil erosion by water at regional scale,loess plateau of China

The objective of this study is to develop a unique modeling approach for fast assessment of massive soil erosion by water at a regional scale in the Loess Plateau, China. This approach relies on an understanding of both regional patterns of soil loss and its impact factors in the plateau area. Based on the regional characteristics of pre- cipitation, vegetation and land form, and with the use of Landsat TM and ground investigation data, the entire Loess Plateau was first divided into 3 380 Fundamental Asses...     

Numerical simulation of seawater intrusion from estuary into river using a coupled modeling system

One of the most important causes of the freshwater shortage in estuarine area is the increasing seawater intrusion into the river. To simulate seawater intrusion properly, two important factors should be considered. One is the bidirectional and time-dependent coupling effects between river discharges and tidal forces. The other is the three-dimensional and stratified structure of dynamic processes involved. However, these two factors have rarely been investigated simultaneously, or they were often simplified in previous researches, especially for the estuary connected with an upstream river network through multiple outlets such as the Pearl River Estuary (PRE). In order to consider these two factors, a numerical modeling system, which couples a one-dimensional river network model with a three-dimensional unstructured-grid Finite-Volume Coastal Ocean Model (FVCOM), has been developed and successfully applied to the simulation of seawater intrusion into rivers emptying into the PRE. By treating the river network with a one-dimensional model, computational efficiency has been improved. With coupling 1D and 3D models, the specification of up-stream boundary conditions becomes more convenient. Simulated results are compared with field measured data. Good agreement indicates that the modeling system may correctly capture the physical processes of seawater intrusion into rivers.     

油藏地质建模及实时跟踪研究

为了提高采收率,降低开发风险,以滩海地区某油田为研究对象,结合地质、测井、地震等资料,对该油藏进行实时跟踪地质特征综合研究。应用地质建模、随钻测井、地质导向等技术,建立了精细的三维地质导向模型,并根据随钻测井数据和综合地质信息,实时验证构造和储集层信息,对导向模型不断校正,使模型与实钻结果一致,还以该模型为基础,优化水平井钻井的前进轨迹。结果表明,此种方法的应用降低了海上油田开发风险,能取得良好的开发效果。     

基于地学信息的土壤属性高精度曲面建模

目前土壤属性的曲面建模面临两大问题,一是缺乏足够多的采样点进行模拟,二是采样点的土壤属性与环境变量间存在非线性关系。高精度曲面建模(HASM)方法在如何融合地学信息对土壤属性进行空间插值,尚需深入研究。本文提出高精度曲面建模与地学信息相结合的土壤属性空间插值方法(High accuracy surface modeling for soil properties, HASM-SP),分别基于研究区的土壤类型、土地利用类型和母岩类型,模拟了江西省典型红壤丘陵区土壤的速效磷(AP)、锂(Li)、pH、碱解氮(AN)、全钾(K) 和铬(Cr) 6 种土壤属性的空间分布。将HASM-SP与普通克立格(OK)、OK与地学信息相结合的方法(OK-Geo) 和分层克立格(SK) 相对比,结果表明：结合地学信息可以使插值方法(HASM-SP和OK-Geo) 模拟结果的平均误差更趋近于0;相对于其他3 种方法,HASM-SP具有较小的平均绝对误差和均方根误差。从模拟的空间分布图上来看,HASM-SP获得了由于地学要素类型突变导致的土壤属性空间变异的细节信息。因此,基于地学信息的土壤属性高精度曲面建模方法(HASM-SP) 与传统插值方法相比,不仅提高了土壤属性空间分布的模拟精度,还能更好地刻画突变边界处土壤属性的空间变异,使土壤属性分布图更好地符合地学规律和实际情况。HASM-SP的提出对于丰富土壤属性的高精度曲面建模理论具有重要意义,并为土壤管理、精准农业的实施以及区域环境规划等提供科学依据。     

一种InSAR大气相位建模与估计方法

为了削弱大气延迟对干涉结果的影响以提高InSAR的测量能力,本文在InSAR大气相位特征分析的基础上,研究了一种新的InSAR大气相位建模与估计方法.首先采用稳健估计确定大气垂直分层部分的模型参数,然后利用基于Matern模型的Kriging插值估计大气紊流部分,最后应用估计的大气垂直分层和紊流资料改正InSAR测量结果.利用覆盖河南义马地区的ASAR数据对本文提出的方法进行了验证,结果表明去除大气影响后,InSAR重建的DEM与参考DEM的高程差异的均方误差由19.5m降至5.3m,精度提高了约72%.同时,改正后的干涉图更合理地揭示了义马矿区的沉降漏斗情况,进一步验证了本文方法的有效性.     

TRMM数据在中国降雨侵蚀力计算中的应用

长时间序列降雨过程资料的获取一直是降雨侵蚀力计算中的一个难题。尝试利用地面实测站点数据分别对TRMM(Tropical Rainfall Measuring Mission)卫星的3B43和3B42数据进行回归建模和订正,并采用订正后的3 h平均降雨强度代替30 min最大降雨强度,同时基于TRMM数据的EI180的降雨侵蚀力算法,计算出了全国南北纬50°范围(TRMM覆盖区)内2013年月、季和年降雨侵蚀力;最后分别计算了省域和区域尺度下的降雨侵蚀力对全国尺度下的结果进行对比验证。结果表明:(1) TRMM降水数据比地面站点观测的降水量略大,但与实测站点数据具有很好的线性回归关系,其季尺度决定系数R²均较高,由此也说明了TRMM数据可以很好地反映全国范围内降雨的季节性变化。(2)利用订正后的TRMM3B42数据计算出研究区内的年均降雨侵蚀力为536.02 MJ·mm·hm^-2·h^-1·a^-1,其降雨侵蚀主要集中在5~8月份。(3) 2013年全国降雨侵蚀变化趋势由东南向西北方向逐渐降低,且沿海省份较内陆省份降雨侵蚀较高。(4)通过对年降雨侵蚀力结果与实测站点降雨量以及订正的TRMM降水数据分析表明,降雨侵蚀力与降水之间存在着紧密的二次非线性关系。(5)通过尺度验证,其中省域尺度验证误差为8.34%,区域尺度误差仅为0.24%,由此说明了TRMM数据在不同尺度下均具有良好的适应性,同时也验证了方法在不同尺度下的有效性。该方法为有效解决土壤侵蚀中降雨强度计算资料缺乏的瓶颈,同时也为降雨侵蚀力的计算提供了一条有效的途径。     

基于遥感影像的卫星颤振探测分析的关键技术与实现

姿态颤振是高分辨率卫星普遍存在的复杂现象,随着卫星的复杂性和敏捷性的提高,故其对成像质量的影响机制和相应的探测与补偿方法,成为高分辨率卫星对地观测研究的关键问题。本文介绍了基于遥感影像的卫星颤振探测原理和关键技术,利用传感器的构造特点,通过不同波段的多光谱影像,以及不同视角的全色立体影像间的密集匹配精确量测和获取影像视差差异值,反演卫星姿态颤振的规律和特性,从而对规律性的颤振现象进行建模和补偿。鉴于上述理论,在Visual C++的平台下,研制了卫星颤振探测分析系统,设计了以计算机性能优化的图像分块并行算法。测试结果表明,该软件能有效探测出0.1像元偏移的卫星姿态颤振,并可对规律性颤振进行建模和补偿,有较好的稳定性和并行效率。其已成功应用于资源三号卫星地面应用系统,并可扩展于其他卫星系统的颤振探测分析。     

基于阿基米德螺线的地铁隧道建模方法

提出了一种适应于地铁隧道的三维激光点云建模及变形分析方法.该方法根据盾构隧道断面呈椭圆形状的特点,基于阿基米德螺线极径对螺线形状的控制作用,对隧道断面进行局部插值构建隧道模型,并根据模型点分析隧道的变形情况.使用C#编写了建模程序,并通过实例验证了该方法的有效性.