桩体复合地基桩、土相互作用的解析法   总被引：17，自引：4，他引：13  

池跃君  沈伟  宋二祥 《岩土力学》2002,23(5):546-550

桩体复合地基的设计中,承载力及沉降的计算一直没有较好地考虑桩、土和垫层的相互作用。根据三者的协同作用,推导出大面积群桩中桩、土的荷载传递基本微分方程并给出其解答。该方法提高了计算速度,土性参数均为常规指标,简便易得。该方法还考虑了桩侧阻随侧向土压力的变化以及垫层、土体压缩模量随压力的变化。与有限元计算结果对比表明了该解答的可行性。能够对桩土分担比以及沉降的计算提供帮助,是一种简便实用的方法。  相似文献   

The phase difference effects on 3-D structure of wave pressure acting on a composite breakwater     

D.-S. Hur  K.-H. Lee  G.-S. Yeom   《Ocean Engineering》2008,35(17-18):1826-1841

In designing the coastal structures, the accurate estimation of the wave forces on them is of great importance. In this paper, the influences of the phase difference on wave pressure acting on a composite breakwater installed in the three-dimensional (3-D) wave field are studied numerically. We extend the earlier model [Hur, D.S., Mizutani, N., 2003. Coastal Engineering 47, 329–345] to simulate 3-D wave fields by introducing 3-D Navier–Stokes solver with the Smagorinsky's sub-grid scale (SGS) model. For the validation of the model, the wave field around a 3-D asymmetrical structure installed on a submerged breakwater, in which the complex wave deformations generate, is simulated, and the numerical solutions are compared to the experimental data reported by Hur, Mizutani, Kim [2004. Coastal Engineering (51, 407–420)]. The model is then adopted to investigate 3-D characteristics of wave pressure and force on a caisson of composite breakwater, and the numerical solutions were discussed with respect to the phase difference between harbor and seaward sides induced by the transmitted wave through the rubble mound or the diffraction. The numerical results reveal that wave forces acting on the composite breakwater are significantly different at each cross-section under influence of wave diffraction that is important parameter on 3-D wave interaction with coastal structures.  相似文献   

我国南方MCC的涡度、水汽和热量收支平衡   总被引：4，自引：8，他引：4  

康凤琴  肖稳安 《高原气象》2001,20(3):333-339

采用合成分析方法 ,将我国南方中尺度对流复合体的生命史划分为 7个子阶段 ,详细探讨MCC演变过程中的涡度、水汽和热量收支平衡演变特征 ,着重分析了中小尺度系统在MCC过程中的作用。结果表明 :( 1)在MCC过程中 ,中γ尺度和中 β尺度系统活动是引起涡度不平衡的重要原因。( 2 )在MCC初始阶段有中小尺度对流系统消耗MCC的水汽、热量而积极活动 ,造成MCC的视热汇、视水汽汇。成熟阶段的源区域表明有中小尺度系统的活动造成MCC的视热源、视水汽源 ,这是MCC具有长生命史的原因。MCC后期 ,中小尺度对流系统活动造成的视水汽汇和视热汇 ,与有利的大尺度天气条件的逐渐消亡 ,使MCC渐渐消失。 ( 3 )MCC的形成和启动受大尺度环境场的控制 ;一旦MCC开始活动 ,对流层低层、中层的中尺度对流系统活动对MCC的发展与持续过程有十分重要的作用 ;在MCC前期 ,中小尺度对流活动消耗MCC的总能量而启动 ;在成熟阶段中小尺度对流活动释放总能量造成了MCC的长生命史 ;MCC后期 ,大形势发生改变 (如位势不稳定度的变化等 ) ,积云对流活动和(或 )中尺度对流活动的作用与大尺度形势趋势一致 ,致使MCC消亡。 ( 4 )在MCC前期 ,潜热释放是主要加热因子 ;而后对流垂直输送水汽和热量的作用比对流凝结加热的作用大。  相似文献   

工业CT在复合材料孔隙率分析中的应用   总被引：1，自引：0，他引：1  

曹玉玲  孙玲霞 《CT理论与应用研究》2001,10(4):14-17

目的：研究应用高分辨率工业CT系统对陶瓷基复合材料的孔隙率进行分析的方法，材料和方法：采用俄罗斯INDINTRO公司的BT－50高分辨工业CT系统对陶瓷基复合材料试样进行CT扫描，用自行编制的后处理软件对得到的CT图像进行分析，得出材料的孔隙率，结果：通过此方法得出的结果与超声检测结果相符，说明用高分辨率工业CT系统测定复合材料的孔隙率是可行的，同时对材料进行缺陷检测，密度分析等。  相似文献   

地图信息度量方法的研究   总被引：2，自引：0，他引：2  

刘宏林 《测绘学院学报》1992,(3)

概率统计方法是最早用于确定地图信息量的方法。但是,由于它的种种不适宜性而受到越来越多的怀疑。本文通过对概率统计方法的分析评价,试图跳出概率统计方法的框框,寻找一种更为有效的测度地图信息量的方法——综合指数法。试验结果表明,这种尝试是十分有效的。  相似文献   

夏季高原大气热源的气候特征以及与高原低涡生成的关系   总被引：4，自引：1，他引：3  

刘云丰  李国平 《大气科学》2016,40(4):864-876

利用NCEP/NCAR再分析资料和基于此再分析资料的高原低涡统计数据集,采用线性趋势、Morlet小波、EOF分解、合成分析等方法,分析了1981～2010年夏季高原大气热源气候特征以及与高原低涡生成的联系。结果表明:夏季高原大气热源平均强度为105 W m-2,随时间有减弱趋势,具有明显的年代际变化,存在显著的准3年周期振荡。高原低涡高发年,高原大气热源强度明显高于气候态,主要表现为高原大气热源的水平分布差异。在低涡高发年,涡度平流的空间分布和大气经向垂直环流结构显示:高原沿东南向西北存在500 hPa正涡度平流带,为高原低涡生成提供了有利的涡度场。同时,高原大气热源异常的水平分布促使高原上空产生上升气流,有助于高原上形成低层辐合、气旋式环流,整层上升运动,高层辐散、反气旋式环流的三维流场,促进高原低涡在低层生成,此时高原主体低空为正涡度区。并且,大气热源在垂直方向的变化也影响低涡的生成。最后,根据本文结果和我们前期的相关研究,从热成风原理和高原大气热力适应理论两方面对高原大气热源与高原低涡生成频数的统计结果给出了机理解释。  相似文献   

复合酶制剂对中国对虾消化率的影响   总被引：3，自引：0，他引：3  

仲军  王键鹏 《海洋科学》1995,19(1):57-59

添加复合酶制剂，可以提高对虾内源酶的活性，增强肝胰脏的消化作用。 对虾饲料中添加１％。复合酶制剂可使对虾总消化率和蛋白质消化率分别提高 ４．８１％和２．４６％。  相似文献   

Wave-induced pore pressure around a composite breakwater     

D. S. Jeng  D. H. Cha  Y. S. Lin  P. S. Hu 《Ocean Engineering》2001,28(10)

The interaction between wave, seabed and marine structure is a vital issue in coastal engineering, as well as marine geotechnical engineering. However, most previous investigations have been focused on the wave forces acting on the structure from the aspect of hydrodynamics. In this study, we will examine the problem of wave-seabed-caisson interaction from the aspect of marine geotechnical engineering. Based on Biot's poro-elastic theory (Biot, M.A., 1941. General theory of three-dimensional consolidation. Journal of Applied Physics 12, 155–164), a two-dimensional finite element model is proposed to investigate the wave-induced soil response in the vicinity of a caisson. Based on the numerical model, the water wave driven pore pressure around a caisson will be examined through a parametric analysis.  相似文献   

Natural frequencies of a vibrating repaired panel in an ocean structure     

D.H. FelixD.V. Bambill  C.A. RossitR.E. Rossi  P.A.A. Laura 《Ocean Engineering》2003,30(8):955-963

The present work arose from the need of repairing steel plates badly damaged by corrosion in a portion of the structural element of the naval vehicle. The possibility of removing the portion and replacing it by a patch of a composite material was considered. Its dynamic behavior is altered by the introduction of the patch and the prediction of its new behavior is of great interest in many situations. This condition would appear in other real-life situations like as a localized orthotropic effect caused in the panel by a welding procedure or a metallurgical process. The first four natural frequency coefficients of the composite repaired panel with different types of boundary conditions are determined by means of a variational approach. The displacement function is approximated making use of complete sets of beam functions. The eigenvalues have been computed from (225×225) secular determinants. An independent solution is obtained using the finite element method and a reasonably good agreement with the analytical solution is encountered.  相似文献   

Earth2014: 1 arc-min shape,topography, bedrock and ice-sheet models – Available as gridded data and degree-10,800 spherical harmonics     

《International Journal of Applied Earth Observation and Geoinformation》2015

Since the release of the ETOPO1 global Earth topography model through the US NOAA in 2009, new or significantly improved topographic data sets have become available over Antarctica, Greenland and parts of the oceans. Here, we present a suite of new 1′ (arc-min) models of Earth’s topography, bedrock and ice-sheets constructed as a composite from up-to-date topography models: Earth2014. Our model suite relies on SRTM30_PLUS v9 bathymetry for the base layer, merged with SRTM v4.1 topography over the continents, Bedmap2 over Antarctica and the new Greenland bedrock topography (GBT v3). As such, Earth2014 provides substantially improved information of bedrock and topography over Earth’s major ice sheets, and more recent bathymetric depth data over the oceans, all merged into readily usable global grids. To satisfy multiple applications of global elevation data, Earth2014 provides different representations of Earth’s relief. These are grids of (1) the physical surface, (2) bedrock (Earth’s relief without water and ice masses), (3) bedrock and ice (Earth without water masses), (4) ice sheet thicknesses, (5) rock-equivalent topography (ice and water masses condensed to layers of rock) as mass representation. These models have been transformed into ultra-high degree spherical harmonics, yielding degree 10,800 series expansions of the Earth2014 grids as input for spectral modelling techniques. As further variants, planetary shape models were constructed, providing distances between relief points and the geocenter. The paper describes the input data sets, the development procedures applied, the resulting gridded and spectral representations of Earth2014, external validation results and possible applications. The Earth2014 model suite is freely available via http://ddfe.curtin.edu.au/models/Earth2014/.  相似文献