An approximate method for evaluating the shear band thickness in saturated soils     

X. B. Lu  Wang Shuyun  Wang Yihua  Peng Cui 《国际地质力学数值与分析法杂志》2004,28(15):1533-1541

A formula for the thickness of a shear band formed in saturated soils under a simple shear or a combined stress state has been proposed. It is shown that the shear band thickness is dependent on the pore pressure properties of the material and the dilatancy rate, but is independent of the details of the combined stress state. This is in accordance with some separate experimental observations. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

全野外数字测图简易编码的数据采集方法   总被引：2，自引：0，他引：2  

刘清田  于庆国 《测绘与空间地理信息》2008,31(1):178-180

全野外数字化测图技术在实际工作中得到了广泛应用,但如何在不增加设备的前提下,提高工作效率,是一个非常现实的问题,本文在结合现有的设备基础上,提出了简易编码测图方案,并对其相关内容进行了阐述。  相似文献   

粘性土微观结构简易定量分析法   总被引：20，自引：1，他引：20  

施斌 《水文地质工程地质》1997,24(1):7-10

作者根据计算机图像处理的基本原则，探索出一套粘性土微观结构简易定量分析法，经检验，这种方法简易，有效，对推广岩土结构定量化具有重要意义。  相似文献   

沉降量约束下的黄骅裂谷形成的地球的动力学模式     

杜旭东  漆家福  张一伟  陆春生 《吉林大学学报(地球科学版)》1997,(2)

在计算覆盖整个黄晔裂谷２００口人工井（包括少部分探井）沉降量的基础上，总结本区二种基本沉降曲线模式。统计出热沉降（Ｓｔ）与初始沉降（Ｓｉ）之比为０．６，依此为约束条件与大陆岩石圈伸展的地球动力学正演模式进行对比，与简单剪切模式预测的热沉降与初始沉降之比值及几何效应更接近。进一步证实黄骅裂谷以简单剪切机制形成的地球动力学模式更合理，这与著名的以纯剪模式形成的北海伸展盆地不同  相似文献   

Origin of layering in cumulate gabbros in the Oman ophiolite: Insights from magnetic susceptibility measurements in the Wadi Sadm area     

Kiichiro  Kawamura  Takahiro  Hosono  Huda Mohamed  Allawati  Yujiro  Ogawa  Hidetsugu  Taniguchi 《Island Arc》2005,14(4):564-570

Abstract   Magnetic susceptibility and the anisotropy of magnetic susceptibility were measured on an 800-cm-thick succession of cumulate gabbro in the Sadm area of the Oman ophiolite. The section contained three distinct cumulate units. The susceptibility tends to decrease upward in each from a melanocratic layer (several tens of centimeters thick) to a leucocratic layer (a few meters thick). The susceptibility decreases in accordance with the decreasing number of magnetite grains, which are the alteration product mainly of olivine minerals. This suggests the cyclic downward accumulation of olivine in the cumulate gabbro. The apparent strain deduced from the patterns of magnetic and grain fabrics was the result mostly of simple shear, so that the layering of gabbro is understood to be formed primarily by a crystal cumulus process followed by simple shear deformation.  相似文献   

Population genetic diversity and structure of a dominant tropical seagrass,Cymodocea rotundata,in the Western Pacific region          下载免费PDF全文

Dan M. Arriesgado  Hiroyuki Kurokochi  Yuichi Nakajima  Yu Matsuki  Wilfredo H. Uy  Miguel D. Fortes  Wilfredo L. Campos  Kazuo Nadaoka  Chunlan Lian 《Marine Ecology》2016,37(4):786-800

Cymodocea rotundata is an ecologically important tropical pioneer seagrass species distributed in the Indo‐Pacific region. The population genetic diversity and structure of this species were analysed at 46 sites spanning the Philippines, Ryukyu Islands (northern limit) and Hainan Island, by using microsatellite simple sequence repeat (SSR) markers. Analyses revealed the persistence of C. rotundata likely relies on local population dynamics and fitness influenced by environmental gradients, with sexual reproduction prevalent in the Philippines while the Ryukyu and Hainan populations were predominantly established by clonal spread. Analysis of molecular variance showed significant genetic differentiation (P < 0.001) among three geographic regions: the Philippines, Ryukyu and Hainan. Furthermore, the mean fixation index value was very high (F_ST = 0.36), indicating poor dispersal potential or limited gene flow. Allelic richness and heterozygosity of C. rotundata was comparable in the Philippines and Ryukyu Islands populations. More private alleles were found in the Philippines and excess heterozygotes in the Ryukyu Islands. STRUCTURE analysis revealed that the Ryukyu and Hainan populations were mosaics of admixed alleles of individuals from the Philippines. An assignment test suggested that recruitment occurs from the Northeast Philippines to Ryukyu Islands. These results suggest that the Philippine populations are tropical seagrass hotspots and perhaps the origin of the populations in the Ryukyu and Hainan Islands. This scenario is most likely driven by the Kuroshio Current and island integration events during plate tectonic activities. The Philippine Archipelago is considered of high importance for conservation objectives and management plan of seagrasses. Likewise, the Ryukyu Islands are also important in terms of conserving regional diversity because locally adapted genotypes have important evolutionary potential in the face of environmental change.  相似文献   

南海中尺度涡强度的季节和年际变化分析     

王文杰  刘宇迪  朱金双  沈俊 《海洋科学》2016,40(12):94-106

为了研究南海中尺度涡强度的季节和年际变化规律,利用Matlab提取50 a(1958~2007年)简单海洋资料同化(Simple Ocean Data Assimilation,SODA)月平均数据集中流场和海表面高度场数据,应用一个涡旋自动探测算法对南海中尺度涡初始生成位置进行分析,并分析了海表面高度异常均方根值的季节变化和年际变化。结果表明:50 a里南海中尺度涡主要分布在吕宋岛西北海域、吕宋岛西南海域和越南以东广大海域,秋、冬季中尺度涡能量较高,春季中尺度涡最弱,中尺度涡强度高值区年际变化明显。从季节变化上看,海面高度异常均方根春、夏季最小,秋冬季最大;从年际变化上看,与同时期Nino3指数有显著负相关,周期大约为3 a。  相似文献   

Abrupt behaviours of streamflow and sediment load variations of the Yangtze River basin,China     

Qiang Zhang  Vijay P. Singh  Chong‐Yu Xu  Xiaohong Chen 《水文研究》2013,27(3):444-452

Monthly sediment load and streamflow series spanning 1963–2004 from four hydrological stations situation in the main stem of the Yangtze River, China, are analysed using scanning t‐test and the simple two‐phase linear regression scheme. Results indicate significant changes in the sediment load and streamflow from the upper reach to the lower reach of the Yangtze River. Relatively consistent positive coherency relations can be detected between streamflow and sediment load in the upper reach and negative coherency in the middle and lower reaches. Interestingly, negative coherency is found mainly for larger time scales. Changes in sediment load are the result mainly of human influence; specifically, the construction of water reservoirs may be the major cause of negative coherency. Accentuating the human influence from the upper to the lower reach results in inconsistent correlations between sediment load and streamflow. Decreasing sediment load being observed in recent years has the potential to alter the topographical properties of the river channel and the consequent development and recession of the Yangtze Delta. Results of this study are of practical significance for river channel management and evaluation of the influence of human activities on the hydrological regimes of large rivers. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

从花岗岩中提纯某些单矿物的流程     

周宏登 《华东地质学院学报》1988,(3)

本文经多年的人工重砂分析,从花岗岩中分离提纯出二十多种单矿物,从而总结了一套分离提纯花岗岩单矿物的简易流程。此流程设备简单,成本低,只要与人工精淘密切配合,可获得纯度较高的单矿物。  相似文献   

浅论高密度电阻率法在工程勘测中的应用效果   总被引：22，自引：2，他引：22  

王文龙  陈天逵 《物探与化探》1995,19(3):229-237

以往在工程地质勘测中,电法勘探主要采用的是电测深法,而电测深法又存在测点密度不大、信息量小等缺点.对于某些探测物来说,存在着资料解释困难的现象.为了解决上述问题,我们引进了一种新方法-高密度电阻率法,经过近几年我们对不同探测物的勘探应用,认为高密度电阻率在工程地质勘察中,是一种简单易行,行之有效的方法.  相似文献