胶西北地区三维地质模型构建及意义

为服务于山东深部找矿,结合金矿成矿机理及预测评价,利用Creatar Xmodeling平台建立了胶西北地区三维地质模型,直观、清楚地反映出胶西北地区地层厚度及变化趋势,岩浆岩展布规模、深度及相互接触关系,从空间分布视角可以看出,金成矿与玲珑花岗岩、郭家岭花岗岩、伟德山花岗岩存在密切关联;全方位展示出断裂带之间的关系,...     

Identifying Rocky Seabed Using GIS-Modeled Predictor Variables

Mapping the seabed along the Norwegian coast is costly and time consuming. Hence, finding a modeling method to separate rocky seabed from other substrate types will provide digital maps that may be used to develop cost-effective sampling designs to predict species and habitat distribution. Our approach was to use geophysical data that were quantitative and objectively defined, generalized additive models (GAMs), and Akaike information criterion (AIC) to develop statistical models and select among them. We found that slope, terrain curvature, wave exposure, and depth predicted rocky seabed occurrence with a high degree of certainty.     

Tsunami Inundation Modeling and Mapping using ALTM- and CARTOSAT-Derived Coastal Topographic Data

Coastal topography is the principal variable that affects the movement of the tsunami wave on land. Therefore, land surface elevation data are critical to a tsunami model for computing extent of inundation. Elevation data from India's remote sensing satellite CARTOSAT-1 are available for the entire Indian coastline, while elevation data collected using Airborne Laser Terrain Mapper (ALTM) are only available for selected sections of the coastline. This study was carried out to evaluate the suitability of CARTOSAT-1 and ALTM elevation data sets in the tsunami inundation modeling. Two areas of the coastal Tamil Nadu that were severely affected during the December 2004 tsunami and surveyed extensively for mapping the extent of inundation were selected as the study areas. Elevation data sets from ALTM, CARTOSAT-1 and field measurement collected using Real-time Kinematic GPS (RTK-GPS) were compared for these areas. The accuracy of ALTM and CARTOSAT-1 data, the significance of interpolation methods and data used on model outputs were studied. The analysis clearly revealed that the elevation accuracy of CARTOSAT-1 data (+/?2m) was much lower than ALTM data (+/?0.6m). However, it was found that despite the differing elevation accuracy, both ALTM and CARTOSAT-1 can be used to produce tsunami inundation maps for open coasts with an accuracy of 185 m (2 grid cells) at 75% and 50% confidence level, respectively.     

河谷地形对深覆盖层中防渗墙应力变形影响分析

为研究河谷地形对深厚覆盖层中防渗墙应力、变形的影响,以某沥青混凝土心墙堆石坝为工程背景,模拟了狭窄河谷和宽深河谷并分别建立有限元模型,坝体材料及覆盖层采用邓肯-张E-B模型,防渗墙与覆盖层、基岩之间的接触关系采用无厚度接触面模拟,进行三维非线性有限元计算,对比分析两种河谷情况下防渗墙的应力、变形情况。计算结果表明：狭窄河谷中,防渗墙沉降和水平向位移及防渗墙与覆盖层的不均匀变形均比宽深河谷小,其中不均匀变形最大减小了24.8%;宽深河谷中,防渗墙受河谷地形约束作用较弱,竖直向压应力较狭窄河谷更大,最大增加了40.3%;防渗墙的竖直向压应力最大值位置受中性点位置和河谷地形的共同影响,其中竖直向压应力最大值约30%来自墙顶坝体土压力,70%来自与覆盖层之间的负摩擦力。其研究结果可为不同地形条件下坝基防渗墙的设计提供参考。     

河北省月平均气温分布式模型应用研究

利用1971-2000年河北省及周边126个气象台站的常规观测资料,应用月平均气温分布式模型,实现了起伏地形下河北省月平均气温的分布式模拟,制作出100 m×100 m分辨率的气温空间制图。结果表明：坝上高原和河北省平原地区地势平坦,气温分布比较均匀;燕山山脉和太行山山脉地形复杂,气温受局地地形影响显著。在角度相同的坡地上,偏南坡与偏北坡的气温差异1月>10月>4月>7月。在同一时段,偏南坡与偏北坡的气温差异随坡度的增加而增加;张家口地区多盆地河谷,气温分布均匀且较周围地区高;月平均气温分布式模型在河北省具有良好的模拟精度、时间维和空间维模拟性能及山地扩展性能。     

与挠曲作用相关的一种特殊裂缝形成机制

浙江省临安市上侏罗统劳村组火山凝灰岩露头中发育了很多与挠曲相关的裂缝, 地层构造简单、露头良好, 为研究与挠曲相关裂缝提供了良好的条件.通过对两处野外露头的精细测量, 发现裂缝面平直、且未被充填, 均为构造裂缝, 在剖面上裂缝的组合呈扇形.裂缝面与岩层层面夹角为44°~80°, 裂缝密度随着地层厚度的增加而增加.根据裂缝面与层面的交切关系, 将两组裂缝分别命名为: 锐夹角指示邻层相对运动方向的D裂缝和锐夹角指示本层相对运动方向的D’裂缝.通过对地层挠曲变形的几何分析, 发现两组裂缝的形成是为了调节核部地层在变形过程中产生缩短量和剩余剪切, 地层厚度与地层中产生剩余剪切成正比.结果表明, 地层厚度越大, 形成的裂缝也越多.      

基于三维地质模型的排土场边坡整体稳定性探究

目前所广泛采用的平面应变分析手段,针对排土场边坡稳定性评价时有时会出现某剖面安全系数高于设定允许值,实际中却遭破坏的现象,除了常被提及的力学参数、本构模型等因素,排土场凹形夹持效应和凸形发散作用突出以及滑体端部效应的影响,是分析结果不能准确反映实际的根本原因之一。鉴于此,从平面高程数据、地质剖面、钻孔资料等条件,配合插值效果较为稳定的Kriging法对空间数据进行插值,建立排土场三维地质整体模型。然后,采用自编FISH语言接口程序,将地质模型导入FLAC3D中离散化并计算,较为简单、有效地实现三维地质建模、模型可视化、岩土工程计算分析三位一体功能,有效地克服了平面分析无法解决的上述问题。以攀钢兰尖铁矿尖山第7排土场为实,对其整体稳定性进行应力、应变分析,采用三维强度折减法计算排土场三维整体安全系数,与现场调查及平面计算结果较为一致。基于该模型的计算结果可以有效避免排土场空间效应和滑体端部效应,得到的排土场全域应力-应变规律,对露天矿排土场的生产管理,具有一定的指导意义。     

弥散磁共振成像研究进展

对弥散磁共振成像的核心内容——使用不同强度和方向的弥散信息对完整弥散过程进行三维建模进行介绍.首先根据模型可描述纤维数量将其分为低角度分辨率和高角度分辨率弥散磁共振成像2类,然后根据建模所用弥散采样选择方式将高角度分辨率弥散磁共振成像分为多弥散角度方向模型、多弥散强度模型和综合弥散角度方向和强度模型3类并进行介绍,并对每个具体模型分别从模型设计、模型计算和模型优缺点3个角度进行分析.     

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