考虑扰动影响的土体小应变硬化模型参数试验研究及其在基坑工程中的应用

天然结构性土体容易受到各类施工扰动,导致土体物理力学性质改变,进而影响工程稳定、变形以及邻近环境。针对宁波两种典型土体,分别对原状土和轻、重扰动土以及重塑土开展了三轴试验及一维压缩试验,分析了扰动度对小应变硬化模型(HS-small model,简称HSS模型)主要参数的影响规律,并将其应用于宁波某基坑工程,利用Plaxis3D分析了考虑周边土体扰动影响的坑后土体水平位移变化。研究结果表明,扰动会使土体的强度及刚度参数降低。对于淤泥质黏土,轻扰动试样的参考切线模量E_oed^ref 、参考割线模量E₅₀^ref及参考加卸载模量E_ur^ref值分别降低14%、10%、2%,重扰动试样三参数分别降低43%、14%、15%,粉质黏土三参数也呈现相似降低趋势。在考虑土体扰动影响的情况下,基坑周边两个测斜孔的最大水平位移值分别增大13%、15%,更加接近实测值。研究结果可为小应变硬化模型的参数取值以及考虑扰动影响的基坑工程分析计算提供指导。     

Experimental Research on Supercritical Carbon Dioxide Fracturing of Sedimentary Rock: A Critical Review

Supercritical carbon dioxide(ScCO₂) fracturing has great advantages and prospects in both shale gas exploitation and CO₂ storage. This paper reviews current laboratory experimental methods and results for sedimentary rocks fractured by ScCO₂. The breakdown pressure, fracture parameters, mineral composition, bedding plane angle and permeability are discussed. We also compare the differences between sedimentary rock and granite fractured by ScCO₂, ultima...     

天津市超高层建筑暖通空调设计气象参数评估

利用255m天津气象塔数据定量评估了建筑暖通空调设计气象参数随高度的变化及其对设计负荷的影响,建立了一种气温垂直模型,明确了该模型可推算超高层建筑室外气温,基于此推算超高层建筑暖通空调室外设计气象参数。结果表明:在5—200m处,供暖设计温度、冬季空调室外设计温度和夏季空调室外设计干球温度均随高度降低,200m与5m高度处相比,分别降低2.0℃、1.4℃和2.8℃,导致供暖和冬季空调设计负荷分别增加5.78%和1.36%,而夏季空调设计负荷减少5.85%。基于气温垂直模型得到的200—500m气温数据计算气象参数,发现从200m到500m,供暖设计温度、冬季空调室外设计温度和夏季空调室外设计干球温度均随高度降低,降幅分别为0.52℃/100m、0.50℃/100m和0.66℃/100m。本研究表明,基于地面2m高观测数据计算的建筑暖通空调设计气象参数无法满足超高层建筑暖通空调设计需求,应充分考虑气象参数的垂直变化,选择合理的气象参数,为超高层建筑暖通空调设计提供基础,以保证室内热舒适环境达标,达到降低建筑能耗的目的。     

Characterizing the influence of tide on the physico-chemical parameters and nutrient variability in the coastal surface water of the northern Bay of Bengal during the winter season

The spatial distribution of physico-chemical parameters(sea surface temperature(SST), p H, sea surface salinity(SSS), dissolved oxygen(DO) and Secchi depth) along with filterable nutrients(dissolved inorganic nitrate(DIN),dissolved inorganic phosphate(DIP) and reactive silicate(DSi)) are measured in the winter months of November,December, January and February for four consecutive years from 2009–2010 to 2012–2013 on the shallow continental shelf(20 m bathymetry) of the coastal waters(up to 18 km away from shoreline) of the northern Bay of Bengal(n Bo B) during the highest high tide(HHT) and lowest low tide(LLT) hours for the first time. The variability of the coastal biogeochemical environment is assessed during the HHT and LLT hours and for this purpose, seawater samples are collected from seven different locations of a transect in the coastal region. Physicochemical parameters(except SST) show significant difference in magnitude during the HHT and LLT hours respectively. p H, SSS and DO are found to increase in the HHT hours and vice-versa. The data reveal that during the LLT hours, a relative increase of freshwater input in the n Bo B can have elevated the nutrient concentration compared with that observed during the HHT hours. The ratio of nutrient concentration is found to deviate significantly from the Redfield ratio. The abundance of DIP is much higher compared with that of DIN and DSi.The anthropogenic sources of DIP from the upstream flow(especially the domestic effluent of several metropolises) can be mainly attributed behind such an observation. In order to characterize and establish the trend of such variation in such an important bio-climatic region, long-term and systematic ecosystem monitoring in the coastal water of the n Bo B northern Bay of Bengal should be carried out throughout the year.     

Availability of offloading from an LNG barge

Long-term data sets are discussed for three locations – a southern North Sea location, where sea states are typically dominated by wind-sea conditions, a Northwest Shelf of Australia location, where sea states are often a mix of wind-sea and swell conditions, and a Guinea Gulf location offshore Nigeria, where sea states are dominated by swell. Various types of sea state statistics that have application to availability studies are presented; but databases of these type that also include wind and current data can also be used to estimate response parameters, which can give a more direct assessment of availability, and some example statistics of these are also given. Finally, the availability of offloading an FLNG barge to carrier is evaluated for each of the data sets, for specific operability criteria. Two types of operability criteria are used in the availability evaluations, and the results compared.     

荻在滨海区重盐碱胁迫下的生理响应

滨海地区高盐碱导致生态环境脆弱,与其经济的高速发展极不相适应,故开展耐高盐碱的植物研究刻不容缓。本文采用pH值为8.0、9.0,NaCl盐度在0、5、10、15、20下的溶液对荻进行胁迫处理,通过各项生理响应指标的变化来研究其耐盐碱性。结果表明:随盐碱度增加,荻叶片相对电导率和丙二醛含量呈增加趋势,增加幅度越大荻长势越差;荻体内渗透调节物质脯氨酸的增加趋势不明显,说明荻有耐盐碱性,而可溶性糖含量先降低后升高再降低,且在达峰值后下降明显,说明荻的耐盐碱能力有限;轻微盐碱刺激能促进荻光合色素含量和根系活力的升高,高盐碱抑制其升高。综合分析荻的各种生理表现,认为荻能耐受pH=8.0、盐度0~20和pH=9.0、盐度0~15的较宽盐碱范围,因此荻可作为修复滨海重盐碱地生态景观的备选植物。     

First analysis of eight Algol-type systems: V537 And,GS Boo,AM CrB,V1298 Her,EL Lyn,FW Per,RU Tri,and WW Tri

Analyzing available photometry from the Super WASP and other databases, we performed the very first light curve analysis of eight eclipsing binary systems V537 And, GS Boo, AM CrB, V1298 Her, EL Lyn, FW Per, RU Tri, and WW Tri. All of these systems were found to be detached ones of Algol-type, having the orbital periods of the order of days. 722 new times of minima for these binaries were derived and presented, trying to identify the period variations caused by the third bodies in these systems.     

An updated period analysis for ER Orionis: A definitive solution

An updated period analysis for the overcontact eclipsing binary ER Orionis is presented. Featured is an improved derivation of parameters for the light time effect (LTE) due to the third star (in actuality, a pair of stars) utilising the latest set of eclipse timings. The very good fit between the eclipse timing differences (ETD) plot (otherwise known as an O–C diagram) and the theoretical ETD curve makes possible an improved determination of the rate of mass interchange between the binary pair, dm₁/dt = +1.83(6) × 10⁻⁷ M_ʘ/year. In addition, the mass of the companion system (in actuality, m₃ sin i) and the elements of its orbit were computed. A suggestion is made for a method of future determination of the inclination of the orbit of the companion system.