A complex variable solution for stress and displacement field around a lined circular tunnel at great depth     

Ming‐Bin Wang  Shu‐Cai Li 《国际地质力学数值与分析法杂志》2009,33(7):939-951

By applying the series expansion technique in the complex variable method established by Muskhelishvili, the plane elasticity problem for the stress and displacement field around a lined circular tunnel in conjunction with the consideration of misfit and interaction between the liner and the surrounding geomaterial is dealt with. The tunnel is assumed to be driven in a homogeneous and isotropic geomaterial. The coefficients in the Laurent series expansion of the stress functions are determined. The complex potentials in the liner and the surrounding geomaterial are explicitly derived, respectively. As an example, the case of a lined circular tunnel located in an isotropic initial stress field but subjected to uniform internal pressure is numerically considered. Numerical results indicate that the installation of tunnel liner can reduce the influences of the tunnel excavation on the in situ displacement and stress fields. However, the relative thickness and rigidity of the liner should be in an appropriate range. In addition, the effect of the tunnel excavation upon the displacement field is more significant than that upon the stress field. As far as the stress field in the surrounding geomaterial is concerned, when the ratio between the cover depth of tunnel and the tunnel radius is larger than 5, the results for the stress field in the paper are applicable. When the ratio between the tunnel depth and the tunnel radius is larger than 20, the results are applicable for the displacement field. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

不同结构形式潜堤上的随机波浪运动   总被引：3，自引：0，他引：3  

李昌良  谢媛媛 《海岸工程》2008,27(1):1-9

潜堤在海岸保护和促潍保淤中具有重要的意义。工程效益和经济投入受到潜堤结构形式和高度的影响。基于RANS方程和流体体积（VOF）方法的模型，计算不同潜堤上的波浪运动。潜堤形式包括矩形结构、梯形结构、半圆结构和槽形结构。模拟了不规则波越堤时波浪的破碎特征、破波类型以及波高的变化。通过分析流场和波高分布的变化，得到潜堤上波能散耗的规律，并且得出最优潜堤结构形式。讨论了相对堤顶高度、破碎点位置、相对堤顸宽度、波陡和潜堤结构形式等对波能耗散的影响。  相似文献   

Relationship of Arctic sea ice and Northern Hemispheric 500 hPa Polar vortices     

References： 《极地研究(英文版)》2007,18(1):73-83

Using the NCEP/NCAR reanalysis monthly 500 hPa height data on a 2.5 latitude-longitude grid and 1°×1° sea ice data,the polar vortex area,intensity index and arctic sea ice area index are calculated respectively,and the meridional distribution,period variation and the abrupts in the long range trend are analyzed to study their relationship.The results show that the meridional distribution of sea ice and polar vortex h-ave distinctive difference,the relative positions of them are different in the eastern and western hemispheres,and exept they have periods of 4 months,quasi half year,quasi year,4-5 years and 10 years commonly,and each of them has its own respective variation as well.The sea ice area is decreasing apparently since 1980's,so is the polar vortex area,but their abrupt changge time are different totally.The area of sea ice and polar vortex has prominent positive correlation,but the relationship of sea ice intensity,polar vortex intensity,polar vortex area is complicated.  相似文献   

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吕永清  蔡亚先 《大地测量与地球动力学》2007,27(5):119-122

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济南地区地下水位观测井固体潮对比研究          下载免费PDF全文

苏道磊  董晓娜  王晓军  刘晨 《山东国土资源》2007,23(4):7-10

收集了济南地区3口地下水位观测井的水位观测数据,分析了水位资料的变化规律与差异,重点针对观测井的固体潮效应,采用维尼迪科夫调和分析法求解出各井孔固体潮效应参数值。对比分析了M2波月序列潮汐因子、相对误差的大小,对井孔的内在质量进行了对比分析及客观评价。  相似文献   

论矿山经济技术指标对企业效益的影响     

马江全 《山东国土资源》2007,23(5):24-26

从矿山生产经营的主要指标分析入手,建立以效益为目标函数的经济分析模型,全面进行矿产经济评价,探讨生产成本、出矿品位、贫化率、矿石产量等对矿山经营效果的影响,从而找出影响矿山经济效益的主要因素,进行指导矿山生产。  相似文献   

论相对点位精度的合理评定     

施一民  朱紫阳 《测绘科学》2004,29(2):28-30,33

按现行方法求得的相对点位精度由于未顾及起始数据误差的影响 ,且非实际所需评定的相对点位精度 ,因此并不客观、可靠。本文所提出的协方差基准的概念 ,用来定义相对点位精度和绝对点位精度有其客观性和实用性 ,协方差基准作为控制网点精度的参考基准 ,并不重合于网点坐标的参考基准—坐标基准 ,而可按应用的需要 ,方便地进行协方差基准转换。本文提出了合理评定相对点位精度的新方法 ,并用高精度工程控制网的实测数据进行了分析验证  相似文献   

相对湿度对黄瓜叶片光合特性的影响   总被引：1，自引：0，他引：1  

张婷华  杨再强  李叶萌  张波 《气象科技》2013,41(6):1128-1133

以黄瓜“津优1号”为试材,于2011年4月在南京信息工程大学进行人工环境控制试验,设计8个相对湿度梯度,用LI 6400进行光合参数的测定,系统研究不同相对湿度处理对黄瓜叶片光合特性的影响。结果表明：黄瓜叶片的净光合速率和胞间CO2浓度随着相对湿度的减小而降低;气孔导度、蒸腾速率和叶片的水分利用效率在相对湿度为75%时达到最大;而气孔限制值在相对湿度为75%时降到最低;黄瓜叶片最大光合作用速率（Pmax）与空气相对湿度呈指数关系：Pmax=22375e189085fRH;随空气相对湿度的减小,黄瓜叶片的表观量子效率、光饱和点均降低,而光补偿点增加;相关分析表明,净光合速率与叶面水汽压差呈负相关,而与气孔导度、胞间CO2浓度、相对湿度、蒸腾速率均呈正相关,且相关性均达到极显著水平。  相似文献   

武汉市2018年4—9月臭氧及其前体物非线性关系研究     

陈安雄  胡柯  沈龙娇  钟章雄  段佳鹏  汪羽商  陈文泰 《南京气象学院学报》2020,12(6):729-738

近年来武汉市臭氧污染日益严峻,成为影响空气质量达标的瓶颈,弄清臭氧及其前体物非线性关系是臭氧防控的关键和基础.本研究基于武汉中心城区2018年4—9月臭氧及其前体物在线观测数据,分析出武汉市臭氧浓度受前体物和气象条件等因素的共同影响,呈较为明显的季节变化和日变化特征.观测期间武汉市大气挥发性有机物（VOCs）平均体积分数为32.5×10^-9,烷烃是武汉市VOCs的主要组分,其次是含氧VOCs （OVOCs）和卤代烃.利用基于观测的模型定量分析臭氧与前体物之间的关系,发现削减VOCs会引起臭氧生成潜势的显著下降,而削减氮氧化物则会使臭氧生成潜势升高,说明武汉市臭氧生成处于VOCs控制区.在人为源VOCs中,间/对二甲苯和邻二甲苯的相对增量反应活性（RIR）最高,是影响臭氧生成的关键组分.  相似文献   

Evaluation of cloud vertical structure simulated by recent BCC_AGCM versions through comparison with CALIPSO-GOCCP data   总被引：2，自引：0，他引：2  

WANG Fang  XIN Xiaoge  WANG Zaizhi  CHENG Yanjie  ZHANG Jie  YANG Song 《大气科学进展》2014,31(3):721-733

ABSTRACT The abilities of BCC-AGCM2.1 and BCC_AGCM2.2 to simulate the annual-mean cloud vertical structure （CVS） were evaluated through comparison with GCM-Oriented CALIPSO Cloud Product （CALIPSO-GOCCP） data. BCC-AGCM2.2 has a dynamical core and physical processes that are consistent with BCC-AGCM2.1, but has a higher horizontal resolution. Results showed that both BCC-AGCM versions underestimated the global-mean total cloud cover （TCC）, middle cloud cover （MCC） and low cloud cover （LCC）, and that BCC_AGCM2.2 underestimated the global-mean high cloud cover （HCC）. The global-mean cloud cover shows a systematic decrease from BCCA-GCM2.1 to BCC_AGCM2.2, especially for HCC. Geographically, HCC is significantly overestimated in the tropics, particularly by BCC_AGCM2,1, while LCC is generally overestimated over extra-tropical lands, but significantly underestimated over most of the oceans, especially for subtropical marine stratocumulus clouds. The leading EOF modes of CVS were extracted. The BCC_AGCMs perform well in reproducing EOF1, but with a larger variance explained. The two models also capture the basic features of EOF3, except an obvious deficiency in eigen- vector peaks. EOF2 has the largest simulation biases in both position and strength of eigenvector peaks. Furthermore, we investigated the effects of CVS on relative shortwave and longwave cloud radiative forcing （RSCRF and RLCRF）. Both BCC_AGCM versions successfully reproduce the sign of regression coefficients, except for RLCRF in PC1. However, the RSCRF relative contributions from PC1 and PC2 are overestimated, while the relative contribution from PC3 is underes timated in both BCC_AGCM versions. The RLCRF relative contribution is underestimated for PC2 and overestimated for PC3.  相似文献