Research on the Fatigue Flexural Performance of RC Beams Attacked by Salt Spray

The fatigue flexural performance of RC beams attacked by salt spray was studied. A testing method involving electro osmosis, electrical accelerated corrosion and salt spray was proposed. This corrosion process method effectively simulates real-world salt spray and fatigue loading exerted by RC components on sea bridges. Four RC beams that have different stress amplitudes were tested. It is found that deterioration by corrosion and fatigue loading reduces the fatigue life of the RC and decreases the ability of deformation. The fatigue life and deflection ability could be reduced by increasing the stress amplitude and the corrosion duration time. The test result demonstrates that this experimental method can couple corrosion deterioration and fatigue loading reasonably. This procedure may be applied to evaluate the fatigue life and concrete durability of RC components located in a natural salt spray environment.     

中华山岩体的谱系单位划分及基本特征

中华山岩体形成于中三叠世,可划分出大段、沙田、竹坡、光石岩、光坡脚等5个单元。岩性均国灶云母二长花岗岩,但岩石结构、矿物成分、岩石化学成分、微量元素和稀土元素地球化学有明显差异和演化趋势,为一同源岩浆序列,经区域对比对立中华山超单元;花岗岩属壳源物质熔融型;岩体兼具主动和被动两种就位方式。     

Bedform migration and bed-load transport in some rivers and tidal environments

Reliable field data obtained by directly measuring bed-load transport of fine- to coarse-grained bed material are extremely scarce, mainly because of the difficulty of sampling accurately. Therefore, the verification of bed-load transport formulae is largely based on flume experiments, which refer to unrealistic shallow-water conditions. In this study, some bed-load transport formulae were tested against data from natural environments. As an alternative to ascertaining the bed-load transport rate by sampling the bed-load, the transport rate was deduced from data on bedform height and bedform celerity. For this purpose, 43 sets of data from rivers, representing a wide range of bed material, bedform dimensions and hydraulic conditions were collected as were some sets of data from tidal settings. Two formulae were used for the prediction of the bed-load transport: the formula of Van Rijn (1981) and the Kalinske (1947) formula as approximated by Elzerman & Frijlink (1951) (and, in the present study, slightly modified for application to tidal waters). Both the bed-load function of Van Rijn and the modified formula of Kalinske-Frijlink require data which are easily obtained and that can be measured accurately. At those stages of the flow when bed-load transport was high the Van Rijn function tended to overestimate that transport. For flow stages when bed-load transport was low the opposite was true. The modified Kalinske-Frijlink function gave consistently good results: 86% of the transport rates predicted using the river data were within 0·5–2·0 times the values actually measured.     

Ground-penetrating radar as a tool to detect rock heterogeneities (channels, cemented layers and fractures) in the Luxembourg Sandstone Formation (Grand-Duchy of Luxembourg)

A combined study of radar profiles and thin section analysis supported by modelling of synthetic radar traces reveals that ground-penetrating radar (GPR) reflections generated in diagenetically altered sandstones cannot always be interpreted unequivocally. This is illustrated in the Luxembourg Sandstone Formation, which has been altered diagenetically by selective carbonate cementation and fracturing. Cemented lenses and concretions developed along the bedding planes, especially at places with high primary carbonate content. Cementation resulted in the alternation of cemented carbonate-rich sandy layers (thickness 30–50 cm and variable length) and uncemented carbonate-poor sandstone layers. The ability of GPR to detect the geometry of these lenses and vertical fractures with centimetre apertures has been tested at several antenna frequencies (100, 200, 250 and 500 MHz). Relative dielectric permittivity calculations were carried out to assess variations of this electric property within the cemented and uncemented layers as a function of porosity, calcite and water content in the pores. Two-dimensional full waveform modelling was also carried out to study the effect of conductivity in the sandstones and the effect of interlayer clay seams. At the penetration depth of the radar (7 m with 250 MHz), cemented lenses and concretions could only be detected with GPR when the porosity contrast was sufficiently high, which is not always the case. This conclusion is supported by the modelling. The data also proved the ability of radar to detect large open vertical fractures along which sandstones are weathered. The study has implications for investigations which will use GPR to detect three-dimensional distribution of diagenetic pore filling precipitates as well as secondary porosity development along fractures.     

美姑河断裂活动性研究及对水电工程影响评价

美姑河断裂带穿越拟建的美姑河瓦洛水电站，其展布及活动性直接影响工程建设。通过地貌、第四系、地质构造及地震等野外地质调查和断裂带石英形貌扫描、ESR测年等方法综合研究表明，美姑河断裂带是由3条断层组成的叠瓦断层带，在中更新世（Q2）以来已不具活动性，不属于活动断层，亦不具有诱发地震的能力，因此断裂带活动性对工程建设影响不大。     

Fluid Evolution during HP and UHP Metamorphism in Dabie Shan, China: Constraints from Mineral Chemistry, Fluid Inclusions and Stable Isotopes

The Dabie Shan ultrahigh-pressure (UHP) metamorphic terraneis located in the eastern part of the east–west-strikingQinling–Dabie orogenic belt in China. A major mylonitizedcontact zone of 200–300 m width divides Dabie Shan intothe South Dabie Terrane (SDT) and the North Dabie Complex (NDC).Combined investigation of major and trace element geochemistry,fluid inclusions, and oxygen and hydrogen isotopes constrainsthe fluid history during the metamorphic evolution of the twometamorphic belts, which differ in their fluid and metamorphicevolution. Fluid inclusions in rocks from the SDT are mainlyaqueous with varying salinities, whereas those from the NDCare dominated by CO₂. Low     

支撑向量机及其遥感影像空间特征提取和分类的应用研究

提出了基于支撑向量机（SVM）的遥感影像空间特征提取的新方法，并以SPOT全色波段影像上城市特征信息的提取为应用实例，并与人工神经网络（ANN）等特征提取方法进行综合比较，认为SVM方法不但能够获得比较高的分类精度，而且在学习速度、自适应能力、特征空间高维不限制、可表达性等方面具有优势。     

上海软土人工冻结热力学性质研究

冻土是一种特殊土类,针对理论研究和冻结工程的实际需要,本文对上海地区三种典型软土人工地层冻结后未冻水含量与含冰量、冻胀特性、无侧限抗压强度、三轴剪切强度、弹性模量及泊松比等主要热力学参数和指标进行了测定分析,并提出了几点结论和看法.     

豫西宜洛盆地上二叠统-下三叠统泥质岩地球化学特征与物源分析

宜洛盆地晚二叠世—三叠纪沉积充填演化是秦岭造山带与华北克拉通共同作用的结果,物源分析是揭示盆山耦合的重要手段之一。论文采用沉积地球化学分析的方法对宜洛盆地上二叠统—下三叠统泥质岩地球化学特征与物源进行了研究,结果表明:宜洛盆地泥质岩稀土元素球粒陨石标准化曲线显示轻稀土元素富集,重稀土亏损,为右倾式曲线,元素Eu中度负异常,元素Ce轻微亏损,符合上地壳稀土元素分布特征。泥质岩源区源岩属性判别图解显示,宜洛盆地物源以长英质岩为主,主要来自于上地壳,孙家沟组后期有少量古老基底杂岩混入。构造背景判别图解显示,研究区物源经历了被动大陆边缘为主(孙家沟组下段)—活动大陆边缘为主(孙家沟组上段和刘家沟组)—大陆岛弧为主(和尚沟组)的演化;华北克拉通和秦岭造山带是宜洛盆地重要物源区,华北地台北部内蒙古隆起可能提供了一定量的物源。孙家沟组早期以克拉通内部物源为主,孙家沟组土门段之后秦岭微地块物源供给明显,体现了华北克拉通南缘基底隆升,由被动大陆边缘向秦岭初始"弧-陆"碰撞隆升的构造演化过程。这对深入揭示南华北盆地与周围造山带之间的耦合关系具有重要意义。