低软化点防塌减阻剂研究及在复杂地层中的应用     

熊正强 《地质与勘探》2015,51(6):1175-1180

为解决现有沥青类防塌剂软化点高及较低温度条件下润滑性差等问题,采用沥青及石油树脂等为主要原料,研制出软化点30℃~60℃可调的防塌减阻剂GFT。室内性能评价表明,GFT具有胶体稳定性好、软化点低、乳液粒径小及润滑能力强等特点,而且与冲洗液配伍性强,不会明显增加冲洗液的粘度,并能有效地降低冲洗液的滤失量。在淡水膨润土基浆中加入1%软化点为46℃的防塌减阻剂,基浆的润滑系数降低率达69%。经在山东及安徽等地多个复杂地层钻孔中现场应用,证明了防塌减阻剂GFT对松散破碎地层、见水易分散地层及硬碎地层具有良好的护壁效果,同时能较好地降低钻具扭矩及摩擦阻力。  相似文献   

THE LOW-PRESSURE SYSTEM IN THE VERTICAL VELOCITY OMEGA ON THE SCALE OF SYSTEM SENSITIVITY     

曲维政  范婷婷  杜凌 《热带气象学报(英文版)》2015,21(S1):66-72

In this study, the relationship between scale and vertical velocity in a low-pressure system is explored using the wave characteristics of atmospheric disturbances and the structural characteristics of low-pressure systems. The ω differential equation, as determined by the transient geopotential height field Φ, is solved to obtain an analytical solution composed only of wavelength, horizontal speed, and atmospheric stability, i.e., the ω diagnostic equation of a low-pressure system. This equation also shows that vertical velocity in the low-pressure system is very sensitive to the horizontal scale, i.e., a smaller horizontal scale means a larger vertical velocity.  相似文献   

A diagnostic study of the asymmetric distribution of rainfall during the landfall of typhoon Haitang (2005)   总被引：1，自引：0，他引：1  

Caijun Yue  Shouting Gao  Lu Liu  Xiaofan Li 《大气科学进展》2015,32(10):1419-1430

The precipitation during landfall of typhoon Haitang (2005) showed asymmetric structures (left side/right side of the track). Analysis of Weather Research and Forecasting model simulation data showed that rainfall on the right side was more than 15 times stronger than on the left side. The causes were analyzed by focusing on comparing the water vapor flux, stability and upward motion between the two sides. The major results were as follows: (2) Relative humidity on both sides was over 80%, whereas the convergence of water vapor flux in the lower troposphere was about 10 times larger on the right side than on the left side. (5) Both sides featured conditional symmetric instability [MPV (moist potential vorticity) <0], but the right side was more unstable than the left side. (6) Strong (weak) upward motion occurred throughout the troposphere on the right (left) side. The Q vector diagnosis suggested that large-scale and mesoscale forcing accounted for the difference in vertical velocity. Orographic lift and surface friction forced the development of the asymmetric precipitation pattern. On the right side, strong upward motion from the forcing of different scale weather systems and topography caused a substantial release of unstable energy and the transportation of water vapor from the lower to the upper troposphere, which produced torrential rainfall. However, the above conditions on the left side were all much weaker, which led to weaker rainfall. This may have been the cause of the asymmetric distribution of rainfall during the landfall of typhoon Haitang.  相似文献   

Payments for Ecosystem Services (PES) in the face of external biophysical stressors     

《Global Environmental Change》2015

Economic instruments such as Payments for Ecosystem Services (PES) schemes are increasingly promoted to protect ecosystems (and their associated ecosystem services) that are threatened by processes of local and global change. Biophysical stressors external to a PES site, such as forest fires, pollution, sea level rise, and ocean acidification, may undermine ecosystem stability and sustained ecosystem service provision, yet their threats and impacts are difficult to account for within PES scheme design. We present a typology of external biophysical stressors, characterizing them in terms of stressor origin, spatial domain and temporal scale. We further analyse how external stressors can potentially impinge on key PES parameters, as they (1) threaten ecosystem service provision, additionality and permanence, (2) add challenges to the identification of PES providers and beneficiaries, and (3) add complexity and costs to PES mechanism design. Effective PES implementation under external stressors requires greater emphasis on the evaluation and mitigation of external stressors, and further instruments that can accommodate associated risks and uncertainties. A greater understanding of external stressors will increase our capacity to design multi-scale instruments to conserve important ecosystems in times of environmental change.  相似文献   

基于计算机视觉的相机标定方法     

景国峰 《北京测绘》2021,35(1):122-125

随着航空摄影测量及倾斜摄影技术的不断推广,其相机传感器受内在及外在因素的影响,使得相机畸变参数的准确性并不是稳定如一,因而极大限制了数据处理的效率。针对这一问题,本文以解决相机畸变参数的准确性作为出发点,从相机成像原理出发,分析相机成像中的误差,介绍相机标定的方法,对相机标定进行实验分析,以达到准确标定相机参数的目的,并将计算的畸变参数应用于实际项目的空中三角测量。试验结果表明,获取的畸变参数可提高空三的效率及稳定性。  相似文献   

基于坐标转换的高铁平面精测网复测稳定性分析方法探讨     

杨雪峰  刘成龙  何勇 《测绘与空间地理信息》2021,44(4):35-37,40

首先介绍了现有各级平面精测网复测稳定性分析的常规方法,然后结合GRP网中判别CPⅢ点稳定性的方法,尝试使用三参数坐标转换进行高铁平面精测网复测稳定性分析,最后以某高铁CPI控制网实测数据为例进行分析。结果表明,不能完全使用三参数坐标转换代替常规方法进行精测网的稳定性分析,但可在使用坐标转换后的点位残差进行稳定性评价时,结合常规法进行综合分析,可提高常规法分析判别效率。  相似文献   

非均质地基中平面应变隧道开挖面稳定上限分析     

宋春霞  黄茂松  吕玺琳 《岩土力学》2011,32(9):2645-2650

非均质是软黏土地基中比较普遍的现象,而目前隧道开挖面稳定研究中比较成熟的理论主要是针对均质土体。因此,从塑性极限分析上限法的基本原理出发,采用平面应变隧道刚体平动破坏模式(多块体上限法),考虑软黏土地基的非均质性,推导了平面应变隧道极限支护压力关于隧道埋深、土体重度及土体强度的上限公式。通过与其他方法的比较分析,证明了极限分析方法在隧道开挖面稳定性方面的可行性;利用该方法的计算结果详细探讨了隧道开挖面稳定的影响因素;而且由计算结果可知,地基土的非均质性在影响隧道开挖面极限支护压力的同时,也影响着隧道开挖破坏面的位置和形状,为工程实践提供重要的理论依据。  相似文献   

清江水布垭库区南潭村滑坡特征及其稳定性     

李逵  吴吉民 《中国地质灾害与防治学报》2011,22(3):16-20

南潭村滑坡位于湖北巴东县水布垭镇南潭村,是发育于原斜坡表层及部分浅层风化基岩中的沿岩土接触面或软弱结构面发生滑移的岩土混合质滑坡。本文结合南潭村滑坡的地质环境资料和现场勘察结果,介绍了滑坡的形态特征、结构特征和变形特征,从地质条件、降雨和人类工程活动等三个方面分析了滑坡的形成原因和影响因素,并采用剩余推力法对滑坡的稳定性进行了定量计算。通过对滑坡进行综合评价,提出了排水系统、减载反压、改变种植方式和变形监测等综合防治建议,为滑坡灾害的研究和治理提供借鉴。  相似文献   

降雨作用下山区边坡稳定性分析     

李德心  何思明  李军歌  朱兴华  黄江成 《中国地质灾害与防治学报》2011,22(1):7-10

降雨是诱发边坡失稳破坏的主要原因,本文以坡地水文模型为基础,结合无限边坡稳定计算模型,研究降雨条件下边坡启动的临界降雨条件。通过工程算例表明:降雨量与边坡体稳定系数成反比;滑坡启动的临界降雨量随边坡坡度的增大而减少;随边坡土体内摩擦角的增加而逐渐增加,此分析对降雨型滑坡的研究有借鉴性的意义。  相似文献   

四川达县杨柳垭滑坡特征与稳定性分析     

陈照雄 《四川地质学报》2011,31(1):74-80

达县杨柳垭滑坡直接威胁到杨柳垭变电站的安全运行和云内华川厂职工生命财产安全,并将严重影响数个乡镇近百万人及工矿企业的正常供电,直接经济损失将达到数亿元.因此,尽快开展此处地质灾害勘查与治理工作十分必要.勘查采用了工程地质测绘、钻探、坑槽探及室内试验等手段,查明了滑坡形成机制、变形特征等,进行了稳定性和推力计算,满足了施...  相似文献