沟槽式卡瓦与钻杆摩擦系数的试验研究   总被引：4，自引：0，他引：4  

田宏亮  胡少韵 《煤田地质与勘探》2003,31(1):62-64

卡瓦与钻杆之间的摩擦系数是卡盘夹紧能力计算的一个重要参数。本文介绍了该摩擦系数的一种研究方法,并通过试验研究,得出了沟槽式卡瓦摩擦系数的变化范围和取值依据,明确了影响该系数的诸多因素。本试验研究成果可直接应用于卡盘的设计计算。   相似文献   

特殊地质灾害对井筒的破坏及对策   总被引：1，自引：1，他引：0  

顾孟寒 《工程地质学报》2000,8(2)

从工程地质学角度分析了由于采矿活动所引起的特殊地质条件下的表土变形 ,以及因表土变形而产生的竖向摩擦力和倾复力对井筒的破坏作用。提出在矿井设计与施工中应特别重视工程地质问题及井筒治理的对策。  相似文献   

IMPACT OF THE HEATINC OVER SOUTH ASIA UPON THE SUBTROPICAL HIGH OVER WEST-PACIFIC     

李双林  纪立人 《热带气象学报(英文版)》1999,5(2):141-152

A case is reported, during which the Subtropical High over the Western Pacific(hereafter, SHWP in abbreviation)shifted northwestward and met-yu at Chaniiang River valley ended. Several numerical experiments on SHWP activity influenced by the heating over south Asia monsoon area are carried out, and the statistic significance of the results is checked. The results indicate that the enhancement of positive heating over South Asia will motivate a wave-like series of anomaly centers, which propagate northeastward from the maximum heating center.so that a strong positive potential height anomaly center will set up from North China to Japan at Day 3 result in the enhancement of SHWP. Comparison of the influence upon SHWP by the heating over south Asia monsoonarea with that over ITCZ area south to SHWP is also carried out. It is pointed out that the heating over South Asiamonsoon area tends to favor SHWP northward movement while the heating over ITCZ area tends to thvor SHWP westward stretching. As for the time to begin to influence on SHWP, the heating over south Asia monsoon areafavors the enhancement of SHWP atter Day 3 while that over ITCZ south to SHWP effects after Day 5.  相似文献   

NUMERICAL EXPERIMENT OF MEDIUM-RANGE CHANGE OF THE SUBTROPICAL HIGH Ⅱ. THE INFLUENCE OF THE HEATING SOURCE OVER WESTERN TROPICAL PACIFIC     

巩远发  纪立人 《热带气象学报(英文版)》1999,5(1):9-16

Numerical experiments are carried out using a global spectral model to study the role of an ideal heating source over the western tropical Pacific region in a medium-term weather process that marks the western advancement of the subtropical high in mid-June 1979. The result has indicated that the effect of the ideal heating source is evident in about 4 days after the inclusion in the high and the circulation at mid-and high-latitudes over the eastern part of China; the disturbance produced over the tropical ocean first transfers towards the northwest along the easterly flow on the southern edge of the subtropical high and then divides into two branches as it moves over the westerly over the mid-latitude area, one continuing the journey northwestward and the other turning to the northeast by east, resulting in changes in the subtropical high and the westerly through combined action.  相似文献   

东亚西风急流变化与热带对流加热关系的研究   总被引：38，自引：14，他引：24  

董敏  余建锐  高守亭 《大气科学》1999,23(1):62-70

应用OLR资料和高空格点资料,研究了东亚地区西风急流及其附近的纬向西风与热带地区对流加热场的关系。结果表明西风急流中心的季节变化是和热带加热场的季节变化紧密的联系在一起的。东亚地区的纬向西风强度的年变化与热带加热场的同期及前期状况也密切相关,这种关系可以作为预测我国江淮地区夏季梅雨的一个强信号。  相似文献   

空间非均匀加热对副热带高压形成和变异的影响──Ⅲ:凝结潜热加热与南亚高压及西太平洋副高   总被引：31，自引：8，他引：23  

刘屹岷  吴国雄  刘辉  刘平 《气象学报》1999,57(5):525-538

通过理论分析和数值模拟,研究了降水所致凝结潜热影响副热带高压带断裂的物理机制。基于全型垂直涡度方程的尺度分析指出,强的对流凝结加热的垂直梯度的变化,导致副热带地区对流层高层和中低层的高低压分布呈现出反位相。数值试验证实凝结潜热是决定东半球夏季副热带高压位置和强度的关键因素：东亚季风降雨所致凝结潜热加热使高层南亚高压位于加热中心西侧,中层西太平洋副热带高压位于加热中心东侧。通过定常波的传播,副热带地区的凝结潜热加热对中高纬天气的形成和维持有一定影响。  相似文献   

空间非均匀加热对副热带高压带形成和变异的影响Ⅰ:尺度分析   总被引：56，自引：16，他引：40  

吴国雄  刘屹岷  刘平 《气象学报》1999,57(3):257-263

利用全型垂直涡度倾向方程,讨论了空间非均匀非绝热加热（Ｑ）对副热带高压形态变异的影响。通过简单的空间尺度分析指出,Ｑ的垂直非均匀分布比其水平非均匀分布对副热带高压带断裂成闭合中心的影响更大。在时间尺度较长时,低空的β效应和高层的涡度平流对副热带高压形态的形成有重要作用。在它们影响下,低空副热带高压出现在表面感热加热西侧、深对流凝结加热东侧;而高空副热带高压出现在表面感热加热的东侧、深对流凝结加热的西侧  相似文献   

梅雨锋暴雨过程中两支雨带的数值模拟   总被引：3，自引：2，他引：1  

周顺武  丁治英  顾茗  陈久康 《南京气象学院学报》1999,22(2):211-218

利用中尺度模式（ＭＭ４）对１９８１年６月２７日江淮地区梅雨锋暴雨过程进行数值模拟,取得了与实况比较一致的结果,成功地模拟出南北两支中－α尺度雨带,在此基础上利用模式输出资料进行中尺度诊断分析,揭示了这次天气过程的中尺度结构特征。重点探讨两支雨带形成和维持的机制。并通过干湿对比试验讨论了积云对流潜热反馈作用。研究表明：在这次过程中南、北雨带主要是由于重力惯性波频散、高低空急流耦合等共同作用下的结果。  相似文献   

摩擦桩基桩土间极限摩阻力取值问题探讨   总被引：1，自引：0，他引：1  

陈银生 《世界地质》1999,18(1):54-59

通过对广珠东线高速公路横沥大桥的试桩及土体的工程地质条件分析,总结出影响摩擦桩基桩土间极限摩阻力取值的一般问题以及解决问题的方法和措施。  相似文献   

Wave-Current Propagation over a Frictional Topography   总被引：1，自引：0，他引：1  

ZUO Qihua  DING Bingcan Prof. Senior Engineer  River  Harbour Department  Nanjing Hydraulic Research Institute 《中国海洋工程》1998,(4)

—In this paper the parabolic approximation model based on mild-slope equation is used tostudy wave propagation over a slowly varying and frictional topography under wave-current interaction.A governing equation considering the friction effects is derived by the authors for the first time.A simpli-fied form for the rate of wave energy dissipation is presented on the basis of the wave-current action conser-vation equation and the bottom friction model given by Yoo and O＇connor(1987).Examples reveal thatthe present computational method can be used for the calculation of wave elements for actual engineeringprojects with large water areas.  相似文献