库水位涨落对库岸滑坡稳定性的影响   总被引：9，自引：0，他引：9  

罗红明  唐辉明  章广成  徐卫亚 《地球科学》2008,33(5):687-692

三峡水库正常蓄水后, 库水位在175~145m之间周期性波动, 滑坡地下水渗流状态将会发生较大的改变, 可能导致滑坡失稳.因此, 研究库水位周期性波动下滑坡的稳定性具有十分重要的意义.提出了土水特征曲线的多项式约束优化模型和采用饱和-非饱和渗流数值模型.以赵树岭滑坡为例, 利用有限元数值计算了库水位在175~145m之间波动下地下水渗流场, 将计算得到的孔隙水压力用于滑坡的极限平衡分析, 探讨了库水位上升和下降对库岸滑坡稳定性的影响.研究表明: 多项式优化模型可以很好地拟合非饱和土的土水特征曲线; 库水位上升时滑坡稳定性系数总体逐渐增大, 库水位下降时滑坡稳定性系数总体逐渐减小; 无论是库水位上升还是下降到库水位155m时, 其稳定性系数最小; 同一库水位下, 库水位上升时的稳定性系数比下降时的稳定性系数大.   相似文献   

土壤种子库萌发实验在野外与室内的对比分析   总被引：1，自引：1，他引：0  

王增如  徐海量  尹林克  严成  郑路 《中国沙漠》2009,29(2):264-269

实验室萌发法是目前国内外研究土壤种子库时普遍采用的方法,而实验室与野外自然环境在萌发条件上具有很大的差异,在野外进行萌发实验是否对土壤种子库恢复潜力的估计更具有可靠性？鉴于此,我们在塔里木河下游选择了3个典型断面,分别在野外和实验室进行了土壤种子库萌发实验。结果表明:①野外与实验室萌出的物种相同,但幼苗密度在野外(598.8株\5m-2)明显高于实验室(530.3株\5m-2)。②物种组成中,豆科物种在野外实验幼苗密度明显较高;若以生活型划分,多年生草本和灌木幼苗密度在野外明显高于实验室。③各物种在野外和实验室的萌发特征相似,但在实验室萌发速度较快,萌发高峰期提前了2~3 d。综合来看,对于塔里木河下游土壤种子库的研究,在野外进行萌发实验其结果更具有可靠性。这对今后土壤种子库的研究具有参考意义。  相似文献   

雾化雨入渗对溪洛渡水垫塘区岸坡稳定性的影响   总被引：5，自引：1，他引：4  

胡云进  速宝玉  詹美礼 《岩土力学》2003,24(1):8-12

运用不平衡推力传递法编制了考虑非饱和带基质吸力和暂态附加水荷载等作用的岩坡稳定分析程序ZSLP。根据雾化雨模型试验结果和岸坡护面措施可能发挥的功效,拟定了12种分析工况。在12种雾化雨入渗工况下,用ZSLP程序对溪洛渡水垫塘区岸坡进行了稳定分析。分析结果表明,雾化雨入渗能显著降低岸坡的稳定安全系数,安全系数的降幅对护面措施的功效比较敏感,应重视控制雾化雨的入渗。  相似文献   

Resting Stages of Plankton in Recent North Adriatic Sediments   总被引：6，自引：0，他引：6  

Fernando Rubino  Genuario Belmonte  Anna M. Miglietta  Sebastiano Geraci  & Ferdinando Boero 《Marine Ecology》2000,21(3-4):263-284

Abstract. Plankton-derived resting stages were found in 26 sediment cores collected in the North Adriatic Sea; 46 morphotypes were identified, 38 were attributed to taxa according to their morphology and, in some hatching cases, also according to the morphology of the derived active forms. Six species of Dinophyta were recorded for the first time from the North Adriatic Sea. Each morphotype was described in detail. Twenty-nine resting stages were Dinophyta; one was a Chrysophyta; two were Tintinnina; and six were metazoans. At every site Dinophyta cysts were more abundant than Metazoa cysts. Cyst bank densities were variable, with empty forms generally more abundant than full ones; cyst concentrations were highest at the mouth of the Po River delta.  相似文献   

A DEVICE FOR MEASURING GULLY HEADWALL MORPHOLOGY     

O. W. ARCHIBOLD  D. H. DE BOER  L. DELANOY 《地球表面变化过程与地形》1996,21(11):1001-1005

This paper describes a low-cost device for measuring the three-dimensional morphology of a gully headwall. The device was designed to operate in a gully system with the following characteristics: overhanging banks caused by a thick, dense root mat; retreat of the underlying unconsolidated sediments through small slab failures, leading to a considerable variation in retreat rate at each point on the headwall; and changes in the orientation of the headwall owing to changes in sediment properties and the topographical and hydrological controls of gully growth. The device is used to measure a series of closely spaced vertical profiles of the headwall, and the collected data are combined to draw a contour map showing the distance from the plane of the instrument to the headwall. Comparing maps for sequential times enables retreat rates for the diffferent proportions of the headwall to be quantified.  相似文献   

应用核磁共振成像(NMRI)技术研究复合剂驱油特征     

郎东江  王为民  尚根华 《CT理论与应用研究》2006,15(3):11-16

本文应用核磁共振成像技术,在均值、非均值模型中研究了复合剂驱油动态实验过程。观察及分析了复合剂驱油特征和效果,对复合剂驱油段塞前缘进行了实时跟踪,得到了复合剂驱油段塞前缘油墙的形成及剩余油分布与运移的二维图像,给出了复合剂驱油后,剩余油的饱和度分布曲线。实验表明:在层状非均值地层中,若渗透率差异大,复合剂段塞主要进入高渗层,而波及不到低渗层,即复合剂波及效率低。若渗透率差异小,复合剂段塞大部分进入高渗层,有少部分进入低渗层,即复合剂波及效率较高。  相似文献   

黄河三角洲前缘桩106至黄河海港岸段海底地形冲淤变化研究   总被引：3，自引：0，他引：3  

刘建立  丁继胜  仲德林  雷宁  蒲高军 《海洋科学进展》2006,24(4):539-545

1976年黄河改道从水清沟入海后,黄河三角洲前沿桩106至黄河海港岸段的海底地形遭受强烈侵蚀,岸滩不断蚀退。黄河三角洲强侵蚀岸段岸线监测资料与历史资料分析研究结果表明,1985-2004年该区最大侵蚀深度达7.5 m,其强侵蚀区中心位置经历了由西北向东南移动的过程,范围不断缩小,目前局部地区已发生淤积现象。种种迹象表明,从冲淤并存和以侵蚀为主向冲淤平衡过渡的现象还将长期进行下去。  相似文献   

中国银行业基层网点的空间演化机制     

姚晓明  朱晟君 《地理研究》2020,39(2):384-398

中国银行业改革持续深化,不同类型银行的业务限制和地域限制逐步取消,银行间竞争日益激烈,重新调整网点布局已成为各家银行应对措施之一。重点关注2007—2016年中国银行业基层网点的空间演化路径,在借鉴演化经济地理研究中产业关联思想的基础上,提出地方产业基础的金融关联度和区域间投资的金融关联度两个重要变量,以此构建解释框架。考虑到中国银行业渐进式的改革历程,按银行所有制及银行规模分组进行比较分析。研究发现：① 地方银行市场竞争越激烈会显著提升产业基础、投资流向的金融关联度在银行网点布局决策中的重要性,银行网点会向金融关联度高的地区集聚;② 各影响因素的作用机制随地方银行市场环境和银行成长过程发生变化,表现出阶段性特征;③ 银行的个体异质性也是影响银行网点空间演化路径的因素之一。  相似文献   

库岸边坡倾角及水位变化对红土型库岸稳定性影响研究     

张祖莲  梁谏杰  黄英  邱观贵  袁强 《山地学报》2019,(1):62-69

水库库岸失稳对水库安全运行有重大影响。采用土工试验和干湿循环试验,结合数值计算及理论分析,研究红土型库岸边坡倾角和库水位升降与库岸稳定性的关系。结果表明:(1)在一定初始干密度条件下,红土抗剪强度随水位升降循环次数增加而非线性减小,且在水位升降循环约10次时趋于稳定。(2)在一定水位升降速率、升降幅度和升降循环次数条件下,红土型库岸稳定安全系数随库岸边坡倾角的增加总体上呈减小的趋势,且在边坡倾角为50°左右存在稳定安全系数极小值。(3)在一定水位升降循环次数条件下,水位上升到坡高的60%左右为上升阶段的相对危险区域,且水位上升速率对库岸稳定安全系数影响很小;水位下降至坡高的70%左右为库水位下降阶段的相对危险区域,且水位下降速率越大,库岸稳定安全系数越小。(4)针对一定初始干密度,库岸稳定安全系数先随水位升降循环次数的增加而减小,但在水位升降循环次数约10次后逐渐趋于稳定。库岸岩土体性质及库岸边坡倾角、水位变化都会对库岸稳定产生影响。  相似文献   

Distribution and germination of viable diatom resting stage cells in sediments of the East China Sea     

ZHANG Yuyu  LU Songhui  ZHANG Chuansong  GAO Yahui 《海洋学报(英文版)》2010,29(5):121-128

The abundance and temporal patterns of viable diatom resting stage cells in sediments of the East China Sea in 2006 have been investigated. The abundance of viable resting stages was enumerated with the most probable number (MPN) technique. Overall, 25 diatom species (including varieties) belonging to 16 genera were detected. Viable resting stage cells were common, on the order of 10³ to 10⁶ cells/g dry mass. The abundant taxa included Skeletonema marina, S. dohrnii, Chaetoceros curvisetus and Thalassiosira spp., with Skeletonema accounting for 83.3% of the cell. The effects of temperature (10, 15, 20, 25℃), salinity (20, 25, 30, 35 psu) and light intensity (0, 300, 4 000, 8 000 lux) on the germination of resting stages in sediment samples were also determined. The results showed that light intensity had a significant positive effect on the germination of diatom resting stage cells (p <0.01) and that diatoms could not germinate in darkness. Temperature and salinity had no noticeable effects on the germination. The present study suggests that there are abundant diatom resting cells in sediments of the East China Sea, which could serve as a "seed bank" in the phytoplankton population succession and contribute to the initiation of algal blooms.  相似文献