对岛状融区房建冻害的几点认识——以沱沱河兵站楼房为例

座落在岛状融区中的青藏高原沱沱河兵站楼房,由于跨年度施工,楼房各部位季节冻深和融化速度不一,引起不均匀下沉,致使墙体产生严重裂缝。岛状融区是工程地质环境敏感区。在太阳辐射强烈的青藏高原,现行建筑规范中房屋采暖对冻深的影响系数偏小,建议对北外墙中段和角端应比规范规定系数分别增大0.2和0.3。     

青藏高原的隆起,沙漠和黄土的形成,人类的起源与演化

青藏高原大幅度的隆起,地质历史由第三纪进入第四纪。西域组(或玉门组)底的不整合面应代表我国第四系的下限,约3.00Ma B.P.。随青藏高原的抬升,气候日趋干燥,塔克拉玛干沙漠形成。黄土是由北部戈壁、沙漠中细粒物质被风吹至南部,后经季雨冲洗堆积在盆地中形成的。青藏高原上不存在第四纪大冰盖。人类的起源和发展与青藏高原隆起关系密切,西瓦古猿在向北迁移中灭绝,其旁枝在高原东部形成真正的人属,然后再向北、东迁移,最终演化为智人。     

基于R语言的NetCDF文件分析和可视化应用

气象领域目前有多种广泛应用的气象数据分析和可视化工具集,包括GrADS、NCL、CDO和IDL等。R语言是一种由统计学家开发的统计计算和绘图的语言和环境,具有大数据处理的能力。R语言数量众多的扩展包为R语言用于海量气象数据分析和可视化提供了强有力的支持。基于R语言对NCEP发布的数据集进行了统计分析和可视化,展示了R语言在气象数据处理和可视化方面的应用。结合R语言提供的贝叶斯统计扩展包和高性能并行计算扩展包探讨了R语言在气象数据处理和可视化应用方面的广泛前景。     

华南（东）变质基底特征、古构造型式及铀、金矿化远景

华南（东）变质基底由杨子及华夏两块不同特征的地质体组成，中元古代之后，该地区分别经过了碰撞对接、拉开、再拼贴的演化过程。碰撞对接带和在古裂谷系基础上成型的陆内推覆及平移、剪切型拼贴带构成了本区基底构造主要型式。铀及金矿远景与基底特征关系密切，铀矿主要产于基底裂隆带部位，金则主要产于裂凹（裂陷）带部位。古基底构造交叉部位是中新生代构造活动活跃部位，受其控制的早期横向火山裂谷盆地，在晚期拉张条件下形成的岩浆杂岩带是铀、金、多金属成矿最佳远景区。     

运用STOMP数值模拟器进行多空介质中尿素水解以及方解石沉淀数值模拟

遍布于美国能源部所辖野外场地的地下放射性核素和痕量金属污染对美国能源部的长期监管职能提出了最严峻的挑战。目前较有前景的一个原地固化污染物方法是利用尿素酶催化尿素水解,进而推动方解石沉淀及与之共同沉淀。运用STOMP数值模拟器实施一系列反应性溶质数值模拟来研究系统中水流、运移、反应与反应导致的介质性质变化之间的紧密的非线性耦合,并在研究中系统性增加反应系统的复杂度和物理-化学的非均质性以考察模拟效果。通过调整反应速率表达式中尿素酶浓度和沉淀反应常数,对尿素水解和方解石沉淀速率进行了敏感度分析。结果显示:尿素水解速率是矿物沉淀总量的决定性因素,沉淀物的空间分布既取决于水解速率也取决于沉淀速率;在一维水流柱6个空隙体积的时间段模拟中,观察到了5%的最大空隙度减少;当二维模拟中考虑一个低渗透性包裹体时,被改变的流场重新对生成的沉淀组成物进行了分布,形成了扭曲的反应锋面。模拟结果也显示沉淀在低渗透性区域边界上形成,这说明位于这个区域里面的污染物可能被囊裹而从流线中被隔离起来。     

车载作用下箱形截面梁振动特性的瞬态动力学分析

论文根据磁浮交通道岔梁的结构及受力特点,通过建立合理的瞬态动力学数值模型,把列车作为高速运行的荷载动态作用于道岔梁上。采用瞬态拟动力学方法模拟钢结构梁动力响应特性。研究了道岔梁上关键点位置相应的振幅、反应加速度及其时效特性。通过计算比较精确地获得工程实际中最为关注的梁的最大振动位移和加速度。研究成果可为高速磁浮实际工程设计提供借鉴。     

Geomorphic Evidence for and Rate of Sinistral Strike-slip Movement Along Northwest-trending Faults in Chaoshan Plain

Two sets of active faults,northwest-and northeast-trending faults,are developed in the Chao-shan Plain of East Guangdong.After detailed interpretation of aerophotos,we have found outthat there is the clear phenomenon of sinistral dislocation of drainage system on the Huang-gang-shui fault and part of Fengshun-Shantou fault.Field investigation confirmed that the geo-morphic bodies along the two faults have undergone displacement.Large-scale topographicmapping was made at three displaced sites and samples for age dating were collected from thegeomorphic booies.Calculation indicates that the average rate of sinistral strike-slip movementin the Holocene time amounts to 1.11±0.09～2.69±0.24mm/a along the Huanggangshuifault and 3.26±0.26mm/a along the Fengshun-Shantou fault.These two more active NW-trending faults extend into sea area,where they intersect the NE-trending strongly active Nius-han Island-Xiongdi Isle-Nanpeng Isles fault at a depth of 40～50m in water.The intersection isa location favorable fo     

Trophic Assessment in Chinese coastal systems-review of methods and application to the Changjiang (Yangtze) Estuary and Jiaozhou Bay

Coastal eutrophication has become one of the main threats to Chinese coastal areas during the last two decades. High nutrient loads from human activities have modified the natural background water quality in coastal water bodies, resulting in a range of undesirable effects. There is a need to assess the eutrophic level in coastal systems and to identify the extent of this impact to guide development of appropriate management efforts. Traditional Chinese assessment methods are discussed and compared with other currently-used methods, such as the Oslo-Paris Convention for the Protection of the North Sea (OSPAR) Comprehensive Procedure and Assessment of Estuarine Trophic Status (ASSETS). The ASSETS method and two Chinese methods were tested on two Chinese systems: the Changjiang (Yangtze) Estuary and Jiaozhou Bay. ASSETS is process based, and uses a pressure-state-response model based on three main indices: Influencing Factors, Overall Eutrophic Condition, and Future Outlook. The traditional methods are based on a nutrient index. ASSETS was successfully applied to both systems, classifying the Changjiang Estuary as Bad (high eutrophication) and Jiaozhou Bay as High (low eutrophication). The traditional methods led to ambiguous results, particularly for Jiaozhou Bay, due to the high spatial variability of data and a failure to assess the role of shellfish aquaculture in nutrient control. An overview of the Chinese coastal zone identifies 50 estuaries and bays that should form part of a national assessment. A comparison of methods and results suggests that ASSETS is a promising tool for evaluating the eutrophication status of these systems.     

An empirical relation for parameter mi in the Hoek–Brown criterion of anisotropic intact rocks with consideration of the minor principal stress and stress-to-weak-plane angle

Acta Geotechnica - The parameter mi accounts for the anisotropy of rock strength, and the accurate determination of mi is a primary requirement of the Hoek–Brown (H–B) strength...     

Flood hydrograph coincidence analysis of the upper Yangtze River and Dongting Lake,China

Natural Hazards - In hydrological research, flood events can be analyzed by flood hydrograph coincidence. The duration of the flood hydrograph is a key variable to calculate the flood hydrograph...