某桥梁载荷试验表面裂纹处理探讨

某桥梁竣工的质量检验采用载荷试验,试验过程中,桥梁梁底出现了细小裂纹。经分析,该细小裂纹不影响桥梁的结构安全,经采用粘贴碳纤维修补加固,结果表明效果良好,达到了预期目的。     

京、津、冀累年月平均5cm地温场的估算

采用两种方法，对河北，北京及天津地区１月，４月，７月和１０月累年平均５ｃｍ地湿场进行了估算。一是采用以纬度，经度和海拔高度为因子的多元线性回归模型进行估算；二是利用Ｋｒｉｇｉｎｇ最优内插法对所选站点实测地湿资料进行内插估算。结果表明，以地理位置坐标为因子的多元线性回归估算模型的剩余标准差为０．４－０．７℃，Ｋｒｉｎｇｉｎｇ内插估算的剩余标准差为０．２－０．３℃。此外，回归分析表明，各月累年平均５ｃ     

导向钻进用于管棚支护工程

导向钻进铺管技术一般用于中小直径管线的穿路,穿河铺设工程,最近,地矿部勘探技术研究所非开挖工程公司将这一技术成功地用于穿越高填土铁路的管棚以护工作。     

筑堤工程中任意位置堤基宽度测设方法

通常可以将大坝填方、河堤修筑、道路路基填方等工程称为筑堤工程。这类工程有以下共同特点：第一,分层填料和压实,并且每层厚度必须控制在一定范围内,层层推进,直至设计高程;第二,由于设计的要求和排水的考虑,施工面往往不是一个平面,而是单向或双向坡的斜面,在这种情况下,施工面的堤基宽度与施工面为平面的情况有所不同,这种差异会随着施工面坡度的增大而增大;     

真空联合堆载预压技术在某软土路基处理中的应用

本文详细介绍了真空联合堆载预压机理并以广肇高速公路K54＋350－K54＋560段软弱路基真空联合堆载预压处理为例，详细介绍其施工工艺及监测情况。测试结果表明，该方法是有效的，可在类似工程中推广应用。     

Heat flux apportionment to heterogeneous surfaces using flux footprint analysis

Heat flux data collected from the Baiyangdian Heterogeneous Field Experiment were analyzed using the footprint method. High resolution （25 m） Landsat-5 satellite imaging was used to determine the land cover as one of four surface types： farmland, lake, wetland, or village. Data from two observation sites in September 2005 were used. One site （Wangjiazhai） was characterized by highly heterogeneous surfaces in the central area of the Baiyangdian： lake/wetland. The other site （Xiongxian） was on land with more uniform surface cover. An improved Eulerian analytical flux footprint model was used to determine “source areas” of the heat fluxes measured at towers located at each site from surrounding landscapes of mixed surface types. In relative terms results show that wetland and lake areas generally contributed most to the observed heat flux at Wangjiazhai, while farmland contributed most at Xiongxian. Given the areal distribution of surface type contributions, calculations were made to obtain the magnitudes of the heat flux from lake, wetland and farmland to the total observed flux and apportioned contributions of each surface type to the sensible and latent heat fluxes. Results show that on average the sensible heat flux from wetland and farmland were comparable over the diurnal cycle, while the latent heat flux from farmland was somewhat larger by about 30-50 W m-2 during daytime. The latent and sensible fluxes from the lake source in daytime were about 50 W m-2 and 100 W m-2 less, respectively, than from wetland and farmland. The results are judged reasonable and serve to demonstrate the potential for flux apportionment over heterogeneous surfaces.     

严谨求实 不断创新——中国科学院青藏铁路重大项目2002年年会记实

中国科学院知识创新工程重大项目“青藏铁路工程与多年冻土相互作用及其环境效应”2002年年会于2002年12月23～27日在兰州召开.来自中国科学院寒区旱区环境与工程研究所、铁道第一勘测设计院、中国气象局国家气候中心、同济大学、北京理工大学、中国矿业大学、中国科学院武汉岩土研究所、中国科学院工程热物理研究所、中国科学院高原生物研究所、甘肃省气象局、青海省气象局等十余家科研机构的160位有关项目的科研人员参加了大会,其中有64篇研究论文进行了大会交流.     

古尔班通古特沙漠短命植物分布及其沙面稳定意义

Based on systematically monitoring plants on dune ridges in the southern part of the Gurbantunggut Desert in 2002, this paper, from the angle of dune stabilization by vegetation,describes the temporal and spatial distribution patterns of ephemeral plants on isolated sand dunes,analyses the natural invasion processes of ephemeral plants on human-disturbed sand surface and expounds the importance of ephemeral plants in stabilizing sand dune surface. A total of 45 plant species were identified in the study area, 29 of which are ephemeral plants. Ephemeral plants sprouted in early April and completed their life-circle within about two months. Just as aeolian sand activities came to the strongest stage from April to June in desert regions of northern Xinjiang, the total coverage of trees, shrubs and herbs of long vegetational period on most dune ridges was less than 10%, while the mean coverage of ephemeral plants reached 13.9% in April, 40.2% in May and 14.1% in June. Therefore ephemeral plants acted as the major contributor to dune surface stabilization in the Gurbantunggut Desert.Investigations of vegetation restoration on engineering-disturbed dune surface show that ephemeral plants first recolonized the disturbed dune surface.     

Distribution of Organic Matter, Iron, Mangenese in Surface Sediments in the Nansha Islands Sea Area, South China Sea

Concentrations of organic matter, iron and manganese in the deep sea surface sediments in the Nansha Islands sea area, South China Sea are measured, Horizontal and vertical distributions of iron and manganese are discussed. The vertical distribution of iron and manganese in the sediments results from reduction, diffusion, and redeposition of manganese (or iron) oxide and hydroxide in the sediment. There are the maxima of iron and manganese in solid phase in the top of the sediment, which is caused by the penetration of O2 and the upward flux of Mn^2 ( or Fe^2 ). Manganese bacteria play a very important role in the cycle of solid-phase iron and manganese in the ocean environment. Manganese bacteria oxidize Mn^2 ( or Fe^2 ) in dissolved state to Mn^4 ( or Fe^3 ) in oxidized state under the aerobic condition, whereas they reduce iron and manganese in anaerobic conditions.     

Development of a new index for integrating landscape patterns with ecological processes at watershed scale

Understanding the relationship between landscape patterns and ecological processes has been a central yet challenging research theme in landscape ecology. Over the past decades, many landscape metrics have been proposed but few directly incorporated ecological processes. In this paper, we developed a landscape index, namely, location-weighted landscape index (LWLI) to highlight the role of landscape type in ecological processes, such as nutrient losses and soil erosion. Within the framework of the Lorenz curve theory, we develop this index by integrating landscape pattern and point-based measurements at a watershed scale. The index can be used to characterize the contribution of landscape pattern to ecological processes (e.g. nutrient losses) with respect to a specific monitoring point in a watershed. Through a case study on nutrient losses in an agricultural area in northeastern China, we found that nutrient losses tended to be higher for a watershed with a higher LWLI value, and vice versa. It implied that LWLI can be used to evaluate the potential risk of nutrient losses or soil erosion by comparing their values across watersheds. In addition, this index can be extended to characterize ecological processes, such as the effect of landscape pattern on wildlife inhabitation and urban heat island effect. Finally, we discuss several problems that should be paid attention to when applying this index to a heterogeneous landscape site.