CFD modelling of natural displacement ventilation in an enclosure connected to an atrium

Computational fluid dynamics (CFD) is used to investigate buoyancy-driven natural ventilation flows in a single-storey space connected to an atrium. The atrium is taller than the ventilated space and is warmed by heat gains inside the single-storey space which produce a column of warm air in the atrium and drive a ventilation flow. CFD simulations were carried out with and without ventilation openings at the bottom of the atrium, and results were compared with predictions of analytical models and small-scale experiments. The influence of key CFD modelling issues, such as boundary conditions, solution controls, and mesh dependency were investigated. The airflow patterns, temperature distribution and ventilation flow rates predicted by the CFD model agreed favourably with the analytical models and the experiments. The work demonstrates the capability of CFD for predicting buoyancy-driven displacement natural ventilation flows in simple connected spaces.     

基于状态空间模型的“一带一路”遗产 廊道生态旅游承载力研究

基于状态空间模型,综合生态环境、旅游资源和社会经济3个子系统对生态旅游的影响效果,以"一带一路"上的普洱"茶马古道"为例,构建了分层次的遗产廊道生态旅游系统承载力评价模型。针对不同文化遗产类型,采用GIS技术将各影响因子空间化,最后综合得到生态旅游承载力空间分异结果。研究结果表明:普洱市生态旅游承载力较低,仅有14.1%的区域具备强承载力,其余区域为较强承载、中等承载、较弱承载和弱承载等其他等级。研究可为"一带一路"等类似线性文化遗产旅游可持续发展的战略制定奠定理论和方法基础。     

陕西九子沟铜矿成矿要素及成矿模式研究

九子沟铜矿位于铅硐山—铜牌沟铜铅锌成矿带中部。矿区赋矿部位为星红铺地层内灰岩与千枚岩接触面及其附近,此界面两侧岩性能干性相差大。一方面在北东向应力作用下,在二者接触部位容易形成滑脱,为成矿热液向上运移提供通道。另一方面,二者构成"硅钙面",引发流体物理化学条件变化,导致矿质沉淀。矿床矿体主要呈层状、似层状,局部为透镜状。根据矿区成矿地质环境、矿体特征、成矿物质组分、矿石组构、成矿物质来源等特征,初步确定了九子沟铜矿床的成矿要素及成矿模式。     

粉土对砂不稳定性影响的试验研究

通过对净砂和粉砂土（粉土含量为10％，20％）试样进行三轴不排水试验，研究了粉土对砂不稳定性的影响。试验结果表明：如使用粒间孔隙比es，就可以在与砂土相同的框架内描述粉砂土的不稳定特性。     

基坑工程对邻近地铁隧道影响的分析与对策

上海市闸北区大宁商业中心基坑东侧围护体距离已运行地铁隧道的最小净距仅为5.45 m。本文主要介绍了该工程中为控制隧道变形采取的设计技术措施:盆式开挖配合钢管斜坡撑代替大面积支撑、地铁侧坑内被动区采用水泥土搅拌桩加固和遵循时空效应原理的设计开挖工况等。同时针对本工程设计以变形控制为主的特点,采用了三维连续介质有限元法分析了开挖所引起的环境效应,其中土体采用修正剑桥模型模拟。同时采取了不同计算方案对比分析了采用抽条开挖的有效性,为设计和施工提供了有益的参考。     

Experimental study and modelling of Cr (VI) removal from wastewater using Lemna minor

The removal of Cr(VI) from wastewater by Lemna minor was studied both at laboratory and pilot scale. Laboratory tests were conducted under different conditions of initial Cr(VI) concentration (0.5 and 2.0 mg/l) and temperature (285 and 291 K). Batch experiments were carried out during 16 days in which the chromium concentrations, both in the biomass and in wastewater were measured. Data were used to characterize the biouptake capacity of the biomass; results showed that it increases with the temperature and when the initial Cr concentration decreases. The biouptake process could be fitted by an equation, with a correlation coefficient of 0.98. The removal process was assessed using the data of the variation of chromium concentration in the wastewater with respect to time; this allowed obtaining constant parameters which were applied in a mathematical model for the assessment of duckweed systems in a pilot scale plant.     

交通瓶颈对区域土地利用的制约研究

从交通瓶颈入手,把交通瓶颈作为区域交通承载能力的控制点,研究了交通瓶颈对区域土地利用的制约作用。建立了交通反算用地模型,根据关键瓶颈路段的能力余量可预测出区域内每一地块的可开发余量,以此作为市政有关部门和城市规划、交通规划部门控制土地开发的理论依据。     

The impact of urban street layout on local atmospheric environment

The investigation was carried out to reveal the impact of urban street layout on local atmospheric environment through computational fluid dynamics (CFD) numerical simulations using standard k$k$–ε$\epsilon$ turbulence model. Different street canyon configurations are considered and the flow regimes summarized according to the aspect ratio of the leeward building height and the street width H1/W$H1/W$ and the aspect ratio of the leeward building height and the windward building height H1/H2$H1/H2$. Three regimes are defined to denote the vortices and characteristics of pollutant dispersion in street canyons according to the parameters H1/W$H1/W$ and H1/H2$H1/H2$. It is found that the pollutant transport and diffusion is strongly dependent upon the type of flow regime inside the canyon and exchange between canyon and the above roof air. The study indicated that there is a strong influence of the street layout on the wind field and the pollutant dispersion in the street canyon mainly depends on the vortex structure in the canyon. The results are validated against an extensive wind tunnel experimental (Meroney and Rafailidis) [Journal of Wind Engineering and Industrial Aerodynamics, 1996;62:37–56; http://www.mi.uni-hamburg.de] and the simulated results concluded by Sini [Atmospheric Environment 1996;30:2659–77] and Sang [Atmospheric Environment 2002;36:1137–45].     

盾构隧道近接下穿地下大型结构施工影响研究

建立了盾构掘进三维有限元模型,针对不同的盾构推进力和同步注浆未及时起到支撑作用的施工工况,采用数值模拟和室内相似模型试验方法进行了盾构隧道近接下穿地下大型结构施工的影响研究。研究结果表明,盾构掘进对地下结构周围土体扰动有限,不会产生隧道整体漂移。抗拔桩对地下结构的支撑作用明显,使得地下结构底板的拉应力和压应力交替出现,从而减小了应力量值。新建隧道和既有隧道衬砌结构受力是安全的,不需进行特殊设计。建议在近接地下结构之前10m处,调整盾构机姿态,放慢掘进速度,并将推进力控制在10000kN以内,以确保施工的安全进行。     

筏板-桩-土相互作用的三维弹塑性有限元分析

通过无厚度的接触面单元模拟筏板–桩–土之间的非线性接触特性,同时采用Drucker-Prager弹塑性本构模型描述土的非线性特性,对桩筏基础进行了三维弹塑性有限元分析,得到了筏板–桩–土接触表面上法向应力和摩擦应力的分布以及桩周土体塑性变形发展情况。在此基础上,对筏形基础中筏板和桩的承载力分担比进行了分析。计算结果表明,随外荷载的增大,桩的承载力分担比增大,筏板的承载力分担比减小,但两者的变化幅度不大。