共查询到20条相似文献，搜索用时 46 毫秒
1.
Martin Held 《Computational Geosciences》2010,14(2):311-317
We analyze the geometric set-up of Lindquist’s “The Geometry of Primary Drainage” (J Colloid Interface Sci 296(2):655–668,
2006) and show that his main equation, which models the arc menisci configuration under primary drainage in capillary tube cross
sections, can be solved analytically for the special case of a convex cross section and the wetting angle being assumed 0.
Our approach relies on the Voronoi diagram of the cross section and runs in O(n logn) time for an n-segment cross section. It requires only the solution of n − 2 second-degree polynomial equations. 相似文献
2.
C. Linwood Vincent 《Mathematical Geology》1976,8(6):635-647
Analysis of channel cross sections is hindered by lack of parameters to describe the shape of the cross section. In the situation of a sample of cross sections taken across tidal inlets, if the cross section is expressed as an observation vector, principal-component analysis can be used to derive eigenvectors for the data set. By neglecting eigenvectors that explain little variance, mathematical representation of the original data set is simplified by transformation to the eigenvector space. For 408 cross sections each represented by a 60-component vector, three eigenvectors explain 97.5 percent of the total variance in the data set. The three-dimensional representation simplifies the task of analyzing cross-sectional shape. The physical form of the first three eigenvectors have considerable resemblance to classical types of variation noted in inlet-channel studies. The method is applicable directly to analysis of other fluvial and estuarine channels. 相似文献
3.
生物壳体碳酸盐的稳定氧、碳同位素已经被广泛地应用在古气候、古环境研究中,在生物壳体就位分析中,壳体不同断面上同位素的差异将影响对壳体同位素所指示的环境意义的判断,从而对利用其提取气候环境信息造成不利影响。本文对河蚬壳体不同断面碳氧同位素进行了研究,结果表明:河蚬壳体碳同位素变化序列在不同断面上不存在显著差异,因此在做碳同位素时间序列研究时可以不考虑不同断面差异的问题,在取样过程中可以通过延长取样的长度来获得足够量的样品进行碳同位素的测定;而氧同位素变化序列在不同断面上存在差异,因此在进行壳体就位分析研究时,选取不同断面上氧同位素变化序列对研究结果影响较大,存在壳体断面选择的问题,而在取样过程中取样的长度应控制在一定范围内,避免同一生长环上距离较远位置粉末的混合。文中最后根据壳体不同断面同位素差异确定了在壳体就位分析中如何选取研究断面。 相似文献
4.
地质构造的物理平衡剖面法 总被引：12，自引：1，他引：11
为了使平衡剖面法具普遍性,在经典的几何平衡剖面法３原则基础上提出了物理平衡剖面法．该法的核心是岩层层面法线不变原则和变形匹配原则,兼顾了岩石变形的物理属性和几何属性．理论分析与实践结果表明,该法不仅可提高地质构造剖面的还原精度,而且可以简化地质分析,降低人为误差,提高自动化程度,更适合于大尺度、多期次构造变形剖面恢复． 相似文献
5.
深水海底峡谷内部的粗粒碎屑沉积物不仅可以作为良好的油气储层,也可以较为完整地记录海洋地质环境变迁的相关信息,是目前海洋地质领域研究的热点.为揭示南海北部珠江口外峡谷体系沉积演化过程及其控制因素,利用多波束测深和高分辨率二维多道地震数据,对珠江口外峡谷体系地形特征、沉积充填特征、形成发育过程和控制因素进行研究.研究发现珠江口外峡谷呈三段式发育:上段为NW-SE走向,宽度超过30 km,侵蚀强度不大,横截面为不规则形态;中段为E-W走向,宽度开始变窄（25~30 km）,横截面呈U型;下段为NW-SE走向,宽度达到最大（25~45 km）,横截面呈U型,中段和下段以沉积作用为主.珠江口外峡谷体系沉积演化主要分为3个阶段:早期阶段（23~15.5 Ma）,水道?海底扇阶段（15.5~11.6 Ma）和峡谷?海底扇/块体流阶段（11.6~0 Ma）.揭示了该峡谷珠江口外峡谷体系的发育和演化主要受构造运动、海平面变化和沉积物供给的控制作用,通过以上分析,将对南海北部海洋灾害地质、深水沉积体系研究及油气资源勘探有重要的指导意义. 相似文献
6.
The erosion and deposition of debris flows at Jiangjia Gully in Dongchuan section of Yunnan province, southwestern China,
was surveyed at 12 cross sections from 1999 to 2003. Deposition occurred in most sections because of the low debris-flow magnitude.
The result was an increase in their elevations except for two sections at D17 and D19, where the channel was diverted in September
1999. As the annual sediment discharge of debris flow increased, the deposited volume decreased in the upper channel and increased
in the lower channel. In each debris flow event, the erosion or deposition at the upper and the lower channel were different,
but the eroded/deposited volume and the trend of erosion or deposition were similar between the neighboring sections. The
average elevation change of all cross sections between consecutive surveys can reasonably represent the debris flow influence
on the channel. Its relationship with the total sediment discharge between two surveys follows a three-stage pattern: when
debris flow magnitude is small, deposition in the channel increases with the magnitude. When the magnitude reaches a certain
level, the deposition begins to decrease and eventually erosion takes place. In three typical cross sections which had similar
channel width, the debris flow showed a clear trend that the deposited volume decreased, while the eroded volume increased
as the discharge of debris flow sediments increased. 相似文献
7.
甘肃靖远石炭系纳缪尔阶高分辨率生物地层研究 总被引：1，自引：1，他引：0
依据对甘肃靖远纳缪尔阶的定量地层研究 ,介绍了图形对比法的基本原理和操作过程 ,建立了靖远石炭系纳缪尔阶生物地层复合标准 ,确定了剖面间的精确对比关系 ,提出了榆树梁剖面是该区发育最为齐全的剖面。榆树梁东沟剖面纳缪尔期地层与榆树梁剖面同期沉积相比 ,缺失了约 30 m厚的地层 ,大水沟剖面靖远组仅相当于榆树梁剖面靖远组中部。 相似文献
8.
文章利用金沙江河谷地貌调查与水利工程选址勘察地质资料,根据河槽纵剖面与18个河谷横剖面的资料以及攀枝花金江河段、会理鱼鲊河段、元谋龙街河段、禄劝凹嘎河段的阶地调查结果,对金沙江下段河槽地貌进行了初步分析,金沙江下段的河谷为典型的深切"V"形河谷,在虎跳峡、乌东德、白鹤滩峡谷段河槽比降发生明显变化。根据河谷阶地下切幅度与形成时代,以T3阶地计算金沙江下段河槽平均下切速率达到0.71~1.18m/ka,以T2阶地计算金沙江下段河槽平均下切速率为0.75~1.36m/ka,因此,近十几万年来,金沙江下段河谷平均下切速率达到0.9~1.0m/ka。现代金沙江河槽底部均堆积了一定厚度的冲积-崩积物覆盖层,最厚的石鼓剖面河床底部冲积物盖层达到173m,一般河段堆积物盖层均达10m以上。金沙江河槽的迁移是河槽下切过程与岸坡崩塌过程综合作用的结果,形成原河槽崩塌阻塞,河槽被动迁移或原河槽改道下切,形成古河槽-离堆山-新河槽的地貌组合,以及河槽侧向迁移3种模式。 相似文献
9.
东海盆地长江坳陷新生代反转构造研究 总被引：10，自引：7，他引：3
通过对长江坳陷中的反转构造研究,认为在长江坳陷中与反转构造相关的背斜构造、推覆构造、地垒构造对油气的存储具有很重要的意义。长江坳陷的构造演化阶段划分为五期:晚白垩世古新世断陷阶段;古新世末期始新世早期挤压反转阶段;始新世坳陷阶段;始新世末期的构造抬升阶段;中新世后的区域沉降阶段。用平衡剖面的方法验证了所解释的地震剖面的合理性,模拟了剖面中重点构造的形成与演化过程,定量地描述了地层拉伸、地层缩短量及褶皱隆升量,为研究有利圈闭提供了重要参考数据。 相似文献
10.
11.
麦秸秆布筋区域与截面形状下的加筋土抗剪强度 总被引：4，自引：0，他引：4
以防腐后的麦秸秆和石灰加筋固化滨海盐渍土,解决由盐渍土的盐胀和溶陷引起的低强度和大变形问题。将布筋区域设计为上半部、中部、下半部、上部1/3与下部1/3处分别布筋,共5种布筋区域;将麦秸秆切割成圆管状、半圆管状、1/4圆管状、圆管碾压后的随机形状,共4种加筋横截面形状。加筋盐渍土和加筋石灰盐渍土的三轴UU抗剪强度表明,适宜的布筋区域均为下半部,适宜的加筋横截面形状均为1/4圆管状。麦秸秆的布筋区域和加筋横截面形状对加筋盐渍土和加筋石灰土的抗剪强度均具有明显影响。加筋可有效地提高黏聚力,但对内摩擦角影响较小。麦秸秆适宜作加筋材料,5种布筋区域和4种麦秸秆截面形状的加筋条件下,均可提高滨海盐渍土的抗剪强度和抗变形性能。 相似文献
12.
分块区域三维地质建模方法 总被引：3，自引：0，他引：3
区域三维地质建模是区域三维地质调查的关键。在大量反复实践的基础上,提出了分块三维地质建模方法,该方法的主要步骤为：以断裂、岩体边界和不整合等为边界,把复杂的三维地质建模区域分解为内部构造相对简单的建模块或建模地质单元;分别对各建模块进行地质地球物理综合研究,编制深部地质剖面,揭示深部地质结构;采用基于剖面的建模方法按照全区统一的坐标系统构建三维地质模型;在完成全区所有建模块三维地质模型构建之后,把各个建模块的三维地质模型集成在统一的三维空间框架下,形成全区的三维地质模型。该方法具有能够简化三维地质建模过程、易于修改完善模型、易于集成模型等优势,能够克服常规的基于剖面的三维地质建模方法中存在的问题,突破了大规模区域三维地质建模的瓶颈。在本溪-临江深部地质调查中的应用表明,采用该方法可以有效构建研究区的三维地质模型,并能充分表达复杂的地下深部地质结构,为开展复杂地区大规模区域三维地质建模提供了一个重要途径。 相似文献
13.
14.
柴达木盆地西部中生界原型盆地及其演化 总被引：2，自引：0，他引：2
柴达木中生界盆地形成时间及其盆地原型研究存在很大争议,主要原因在于对盆地内有无三叠系陆相沉积及其与上覆下侏罗统地层接触关系和中生界原型盆地形成的构造背景等问题认识不清.区域地质调查在盆地西部月牙山北发现中、上三叠统陆相地层与上覆下侏罗统地层整合接触,在此基础上,结合地表露头、古流分析及地震解释资料研究认为:柴达木中生界盆地起始于中三叠世.中生代在古阿拉巴斯套山与古昆仑山间发育一个大的近东西向展布的活动型山间盆地,盆地经历了中-晚三叠世、早-中侏罗世和晚侏罗世-白垩纪三个演化阶段,分别对应发育了中-晚三叠世坳陷型盆地、早-中侏罗世断陷型盆地和晚侏罗世-白垩纪坳陷型盆地三种原型盆地类型.中-晚三叠世盆地分布比较局限,沉积以氧化环境下的红色碎屑岩建造为主,不具生烃能力;早-中侏罗世盆地范围扩大,沉积物以暗色含煤建造为主,主要分布于现今的阿尔金山地区及其山前地带,沉积中心在阿尔金山地区.晚侏罗世-白垩纪阿尔金山快速隆升,成为主要物源区,开始分割塔里木和柴达木盆地沉积,沉积物为红色磨拉石建造.该研究对于准确评价柴达木盆地生烃潜力及合理进行勘探部署具有重要意义. 相似文献
15.
晋祠泉域汾河干流古交段属山区峡谷,河谷大部分河段寒武、奥陶系碳酸盐岩类可溶性岩层裸露,河道渗漏量大。根据试验断面测流数据,建立了不同渗漏段上游断面流量及渗漏系数关系模型,分析各渗漏段渗漏规律,推算渗漏量,为晋祠泉水复流工程汾河干流古交渗漏段补水方案提供参考。 相似文献
16.
S. Henke 《国际地质力学数值与分析法杂志》2010,34(11):1191-1210
Pile installation leads to significant changes in the main state variables of the surrounding soil. In addition, the installation process may have an influence on adjacent or intersecting structures such as pile grillages. In this paper, three‐dimensional numerical analyses are presented to investigate the effects of pile driving with open or closed cross‐sections on the surrounding soil and on adjacent structures. Two different installation methods are used: quasi‐static pile jacking and vibratory pile driving. The numerical models are evaluated and verified using data from field tests performed in situ during the construction of the quay wall at the container terminal CT4 in Bremerhaven. Two case studies are presented to characterize the main influence factors for additional loading on adjacent structures due to pile installation. Finally, a parametric study is conducted showing the influence of the installation method, pile cross‐section and distance of a pile from an existing structure on the additional loading for this structure. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
17.
介绍了部分断面掘进机总体布置的内容、原则和具体要求、各部结构的布置,以及总体参数的确定方法,包括机型大小、外形尺寸、可掘断面、生产率、通用性等,对于正确地设计与使用掘进机有一定的指导意义。 相似文献
18.
三峡引水工程秦巴段隧洞总长占线路总长的80%。为了分析隧洞施工及运营中可能发生的工程地质问题,在地质调查、地应力测量和岩石力学参数测试的基础上,利用Ansys有限元软件对引水工程北部不同深度、不同截面形态的隧洞围岩的应力重分布情况进行了模拟计算,得到了圆形隧洞、城门形隧洞和马蹄形隧洞围岩的应力分布结果。利用Hoek-Brown强度准则,得到了隧洞围岩的强度/应力比值,进而对不同深度、不同截面形态的隧洞围岩的稳定性进行了分析。初步认为:隧洞埋深小于1000m时,应优先考虑圆形隧洞和马蹄形隧洞;埋深大于1000m时,应优先考虑城门形隧洞。这项研究成果为引水工程深埋隧洞的设计提供了参考依据。 相似文献
19.
A microcomputer-aided drafting system is used at the Geological Survey of Canada, Calgary, to make large charts and legends for the Geologic Atlas of Canada. Hand-drafting of Atlas maps may be supplemented by a digital geologic map database created by a new microcomputer and videotracing system at CAL-CAD. Video-tracing is more rapid and discriminating than existing rasterscan and digitizing table systems, as an image of the map is multiplexed (overlain) on-screen with AutoCAD. Interactive tracing and storage of each data type as a separate layer of file aids accuracy, and adds great editing power and output flexibility to geological and geophysical maps, cross sections, logs, and other complex diagrams. New digital and old paper databases can be merged into powerful geographic information systems.Read by M. Marchand (Canterra Energy Ltd., Calgary) at Emerging Concepts, MGUS 87 conference, 13–15 April 1987, Redwood City, California. 相似文献
20.
B. P. Kondrat’ev 《Astronomy Reports》2000,44(5):279-285
We have developed a model for a spheroidal, ring-shaped galaxy. The stars move in a ring with an elliptical cross section at the 1: 1 frequency resonance. The shape of the cross section of the equilibrium ring depends on the oblateness of the galaxy itself, so that the ellipse of the ring cross section is radially extended when the oblateness of the galaxy is small. If the oblateness of galaxy exceeds some critical value, the ellipse cross section is extended along the Ox 3 axis. The shape of the ring cross section is circular for a galaxy with critical eccentricity. The stability of the ring over a wide range of perturbations is studied. A fundamental bicubic dispersion equation for the frequencies of small oscillations of a perturbed ring is derived. Application of the model to the ring galaxy NGC 7020 shows that its ring cross section should be approximately circular. Analysis of the dispersion equation demonstrates that stellar orbits in the arm are unstable (but the instability increment is small). We conclude that stars in the ring of this galaxy should drift from the 1: 1 resonance, and the ring itself should evolve. 相似文献