Gravitational Sedimentation Behavior of Sensitive Marine Ariake Clays     

ZHENSHUN HONG  TAKEHITO NEGAMI  HAILUN GUO 《Marine Georesources & Geotechnology》2013,31(1-2):49-63

It has been well documented that natural marine Ariake clays are sensitive clays. In this study, extensive data of marine Ariake clays are obtained to investigate the gravitational compression behavior for sensitive clays. Analysis results indicate that the compression behavior of remolded Ariake clays is not different from that of other remolded/reconstituted soils. But natural Ariake clays do not follow the gravitational compression pattern reported by Skempton (1970) Skempton, A. W. 1970. “The consolidation of clays by gravitational compaction”. In Q. J. Geol. Soc 373–411.  [Google Scholar] for natural sedimentary soils. At a given value of effective overburden pressure, the void ratios of natural Ariake clays are almost independent of liquid limits. Most natural Ariake clays lie above the sedimentation compression line proposed by Burland (1990) Burland, J. B. 1990. On the compressibility and shear strength of natural clays. Gèotechnique, 40: 329–378. [Crossref], [Web of Science ®] , [Google Scholar]. When the liquid limit is larger than 90% and the ratio of natural water content over liquid limit ranges 0.8–1.1, the natural Ariake clays lie around the sedimentation compression line. In addition, the natural Ariake clay with higher value of the ratio of natural water content over liquid limit lies above the natural Ariake clay with lower value of the ratio of natural water content over liquid limit. Salt removal is the most probable cause for such a phenomenon.  相似文献   

潜孔锤反循环钻进技术在某水电站的试验应用   总被引：1，自引：0，他引：1  

殷其雷  殷琨  柳鹤  甘心 《吉林大学学报(地球科学版)》2014,44(3):961

水利工程中的钻孔工程具有特殊的工况,采用正循环潜孔锤钻进方法在狭窄封闭的洞室内进行钻孔施工,粉尘污染严重,施工环境恶劣,影响作业工人的身体健康。为了解决施工洞室内的粉尘污染问题,在某水电站的排水孔施工中,首次应用了潜孔锤反循环钻进技术,并在上仰孔和下行孔施工试验中获得成功,有效控制和降低了洞室内的粉尘问题,有利于维护良好的施工环境。设计的A、B两种结构类型钻头主要差别是内喷孔的位置不同,A型钻头的内喷孔设计在花键上的各个平键之间,B型钻头的内喷孔则设计在花键的平键上。CFD数值模拟计算结果显示,A型钻头对环空抽吸的空气量是0.199 987 04 kg/s,略大于B型钻头的0.177 524 64 kg/s,说明A型钻头的抽吸能力优于B型钻头。上仰孔和下行孔的钻进试验结果表明,内喷孔设计在花键上的各个平键之间且具有双排12个内喷孔的A型钻头结构更为合理,在施工中A型钻头比B型钻头的孔口粉尘少。从反循环排渣效果看,A型钻头破碎的大部分岩粉和大颗粒岩块从中心通道排出,反循环排渣效果优于B型钻头。  相似文献   

Continuous-time monitoring of liquid water content in snowpacks using capacitance probes: A preliminary feasibility study     

《Advances in water resources》2014

Liquid water in snowpacks rules wet snow avalanche formation, surface albedo and snowmelt runoff timing. By now, volumetric liquid water content (LWC) measurements are collected mainly with destructive methods, while continuous-time and non-invasive measurements would be preferable to track its time dynamics. Here, we assess the feasibility of continuous-time monitoring of LWC using EnviroSMART® capacitance sensors. These were conceived to track liquid water dynamics in soils, and their use in snow is evaluated here for the first time, as far as we know. A field case study was settled up in April 2013 within an Italian Alpine valley. An instrumental set up with eight capacitance sensors was installed. Two time-domain reflectrometers were added to the aim of comparison. To assist in interpreting the signal of the capacitance sensors, two laboratory tests were run, and a FEM model was implemented. This preliminary study demonstrates that capacitance sensors are sensitive to increasing LWC, although their long-term installation in snow entails the development of an air gap around them, due to localized melting, air turbulence and solar radiation absorption, which hinders following LWC variations. As a result, capacitance sensors readings are challenging to be interpreted quantitatively. Perspectives on future investigation are discussed to bring the proposed procedure towards long-term applications in snowpacks.  相似文献   

Usage of Hydrophobic Ionic Liquid [BMIM][PF6] for Recovery of Acid Dye from Wastewater and Sequential Application in Tussah Silk Dyeing          下载免费PDF全文

Jie Lin  Yi Teng  Yanhua Lu  Sheng Lu  Xu Hao  Dehong Cheng 《洁净——土壤、空气、水》2014,42(6):799-803

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Assessing the rock glacier kinematics on three different timescales: a case study from the southern Swiss Alps          下载免费PDF全文

Cristian Scapozza  Christophe Lambiel  Claudio Bozzini  Stefano Mari  Marco Conedera 《地球表面变化过程与地形》2014,39(15):2056-2069

Surface temperature increases since the 1990s have often been associated with an increase in the speed of rock glaciers. Evidence of similar links on the centennial to millennial scale are, however, still lacking due to less focus to date on the medium‐ and long‐term kinematics of these landforms. In order to assess (palaeo)climatic variations in rock glacier kinematics, we analysed the movements of the Stabbio di Largario rock glacier in the southern Swiss Alps using three different timescales. The Schmidt hammer exposure‐age dating (SHD) was applied to study long‐term kinematics in order to extrapolate the minimal age of the formation of the rock glacier, which may have started its development after the Mid‐Holocene climate optimum, and to detect possible accelerations of the horizontal surface velocity during the Medieval Warm Period. Georeferentiation and orthorectification of six historical photographs of the rock glacier taken between ad 1910 and today were analysed using monoplotting to detect the rock glacier displacement on the decennial scale from the end of the Little Ice Age. Finally, differential global positioning system (dGPS) monitoring data available since ad 2009 were used to assess annual and seasonal creep rates of the rock glacier at present. Our results show a link between the periods of increase in mean air temperature on different timescales and variations in rock glacier kinematics and provide important new insights into rock glacier development and evolution on the long‐term scale. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Comparison of electronic and mechanical Schmidt hammers in the context of exposure‐age dating: are Q‐ and R‐values interconvertible?          下载免费PDF全文

Stefan Winkler  John A. Matthews 《地球表面变化过程与地形》2014,39(8):1128-1136

Application of Schmidt‐hammer exposure‐age dating (SHD) to landforms has substantially increased in recent years. The original mechanical Schmidt hammer records R‐(rebound) values. Although the newly introduced electronic Schmidt hammer (SilverSchmidt) facilitates greatly improved data processing, it measures surface hardness differently, recording Q‐(velocity) values that are not a priori interconvertible with R‐values. This study is the first to compare the performance of both instruments in the context of field‐based exposure‐age dating with a particular focus on the interconvertibility of R‐values and Q‐values. The study was conducted on glacially polished pyroxene‐granulite gneiss, Jotunheimen, southern Norway. Results indicate that mean Q‐values are consistently 8–10 units higher than mean R‐values over the range of values normally encountered in the application of SHD to glacial and periglacial landforms. A convenient conversion factor of ±10 units may, therefore, be appropriate for all but the softest rock types close to the technical resolution of the instruments. The electronic Schmidt hammer should therefore be regarded as a useful complement and potential replacement for the mechanical Schmidt hammer. Conversion of published R‐values data to Q‐values requires, however, careful control and documentation of instrument calibration. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

利用地基微波辐射计反演兰州地区液态云水路径和可降水量的初步研究   总被引：7，自引：1，他引：6  

黄建平  何敏  阎虹如 《大气科学》2010,34(3):548-558

液态云水路径 (liquid water path, LWP) 和可降水量 (precipitable water vapor, PWV) 是描述天气和气候的两个重要物理量。目前, 针对液态云水路径和可降水量的直接观测较少, 特别是在我国干旱半干旱黄土高原地区, 至今没有获得系统的观测值。本文利用兰州大学半干旱气候与环境监测站 (SACOL) 近两年的微波辐射仪观测资料, 分析了黄土高原半干旱区液态云水路径和可降水量的变化特征。首先引入Liljegren et al.(2001) 的反演方法并加以改进, 计算得到适合黄土高原地区的反演参数, 利用改进后的反演方法计算近两年的液态云水路径和可降水量。分析结果显示, 与TP/WVP-3000型12通道微波辐射计的直接输出结果相比, 本文反演结果与实际情况更加吻合。在SACOL代表的黄土高原地区, 95%的云水路径值都在150 g/m2以下, 95%的可降水量值都在3 cm以下。由于SACOL的降水受亚洲季风的影响, 液态云水路径日均值冬季最小, 秋季最大, 其日变化规律显示半干旱区液态云水路径大体上呈双峰分布, 峰值主要出现在日出和日落时分。卫星反演资料的年变化趋势与地基反演结果比较吻合。因此, 运用卫星反演的液态云水路径来分析我国西北地区的空中云水资源是一种比较可信的手段。  相似文献   

海雾的准周期振荡特征   总被引：1，自引：0，他引：1  

沈忱  黄健  刘寿东 《热带气象学报》2010,26(1):71-78

根据南海北部海雾外场观测获取的高分辨率液态含水量、长波辐射通量数据,采用小波分析方法分析了2008年3月16—17日和18—19日两次海雾中的液态水含量、净长波辐射通量的变化特征,讨论南海北部海雾发展和维持的冷却机制。结果显示:(1)无论在有云或无云条件下,海雾都可发展和维持;但前者的液态含水量明显小于后者,而风速大于后者;(2)在地面海雾的生成之前和生成初期,净辐射通量都存在准周期振荡现象,无论无云/有云,地面海雾液态水的大幅度发展的阶段都存在含水量的准周期振荡现象;(3)含水量的准周期振荡现象与振荡发生时段的长波辐射通量关系不大,而主要通过湍流对液态水的混合作用与高空海雾液态水大量生成阶段的雾顶长波辐射间接相关。(4)海雾的生成都与雾顶长波辐射冷却密切相关,但发展和维持可通过不同的冷却机制,既可通过海气间湍流热量输送和辐射传输,也可通过雾顶长波辐射冷却。  相似文献   

对流层上层东半球副热带西风急流与副热带(南亚)高压的关系   总被引：7，自引：4，他引：3  

刘杰  况雪源  张耀存 《气象科学》2010,30(1):34-41

用NCEP/NCAR月平均再分析资料对南亚高压和对流层上层西风急流的季节变化及盛夏两类型态进行对比。结果表明,南亚高压和西风急流中心都有从冬到夏的西移北进和从夏到冬的东退南撤,急流中心位于南亚高压中心北侧。东亚夏季风盛行期间南亚高压中心的北移提前于西风急流中心的北移,二者的强度呈反相的季节变化。一般情况下,伊朗高压对应西部急流型,青藏高压对应东部急流型。典型东、西部急流年份中高纬气温及高度场的差异表明气压梯度力强弱对比是急流东西型变化的主要原因,南亚高压的位置基本上决定了急流中心的型态,但由于南亚高压具有"趋热性",而急流的移动符合热成风的规律,因而二者的热力影响机制有所不同。  相似文献   

河北两次大（暴）雪过程对比分析   总被引：3，自引：0，他引：3  

赵斌  赵萃萍  闫巨盛  马小山  冯天卿 《气象科技》2010,38(3):281-288

选取河北省2003年和2004年两次较大的降雪过程,利用常规气象资料和NCEP再分析资料,对它们的环流形势和物理量场作了对比分析。结果表明,500 hPa南北两支槽在110°E附近同位相叠加、地面气压场"北高南低"并在河套地区有倒槽生成是河北出现大(暴)雪的有利形势。低层暖温舌和暖平流的存在为大(暴)雪的形成提供了较好的热力条件。槽前西南气流、低层偏东气流和低空急流都能为产生大(暴)雪带来充足的水汽。高层辐散、低层辐合的水平散度结构和整层为垂直上升气流的分布,加强了上空的抽吸作用,有利较大降雪的发生。而整层是正涡度(正垂直螺旋度)对垂直上升运动最有利。925 hPa和850 hPa温度同时降至0℃以下,且地面气温小于等于1℃是适合降雪的温度条件。  相似文献