预应力锚固技术在桥台加固中的应用

预应力锚固技术由于其高效、经济的特点,近年来在各类岩土加固工程中得到了广泛的应用,高家庄2号桥台加固采用了对穿预应力钢筋加固技术,在加固工程施工过程中,为了保持桥台的稳定采取了临时加固措施,通过对这一工程实践特点的分析和论述,在施工程序和方法方面进行了探讨和总结。     

Temporary Migration and the Labour Market in Australia

Australia's labour market is most influenced by international migration among OECD nations, but Australian research on this issue focuses almost exclusively on permanent settlement migration. The present paper, however, demonstrates that non-permanent migration has an important impact on the Australian labour market, although such migrants are not included in standard data collections and research on migrants and the labour market. A number of data sources are utilised to estimate the labour-market impact of Working Holiday Makers, Temporary Business Entrants, Overseas Students, and New Zealand temporary migrants. It is shown that their impact is equivalent to more than 400?000 full-time jobs. However, the effect is magnified because it is concentrated in particular sectors of the economy and in particular communities within Australia. A number of issues relating to temporary migration are discussed, including the nature of its relationship with permanent migration, the effects on job training, and the implications for regional development.     

软着陆保护橡胶支座隔震体系振动台试验研究与比较

本文对一基础隔震模型进行了软着陆保护振动台模拟地震动试验,展示了该隔震体系在发生水平向大变形条件下,在不同后备支座以及滑移面摩擦系数不同情况下,轴压力从承载支座向后备支座转移的情况。结果表明:软着陆隔震保护体系不仅保护了承载支座免遭大变形失稳破坏,同时还能提供摩擦阻尼,将隔震层位移和上部结构层间位移控制在允许范围内。文中对隔震层位移、上部结构最大层间位移及绝对加速度等进行了分析,所得理论曲线与试验拟合曲线吻合较好。具有很大的应用前景。     

广东贵屿土壤Cd、Hg潜在威胁评价

通过表层土壤、深层土壤、水稻样品及水样的采取与分析,结果表明,水俣病的元凶Hg在广东省贵屿镇土壤中具有极高的富集系数,易在酸性条件下向有效形态转化的弱有机结合态Hg占全Hg的17.74%;痛痛病的元凶Cd在部分土壤中的含量已超过环境承受的极限,且最易与生命体发生作用的水溶态Cd和离子交换态Cd占全Cd的比例高达16.2%。Hg、Cd的块金系数均大于70%,具明显的表层富集特征,与家电拆解作坊表层土壤重金属元素同源性较好,说明Cd、Hg的分布、富集受人类活动影响强烈,其对生态环境和居民健康存在极强的潜在威胁,在特定条件下有可能引发各类地方病。     

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2006??8~10???????-???????????????????????????????????????????????30????????????????????2~5 km(????2???????????????????????????????????????????????????μ??????????)?? ????????4?????????????????398??????????λ????????????δ???????????鵽???40?ε??????????????????????????????????????????????????????????????о??????????????????     

高铁大临设施用地复垦利用辅助系统的设计与实现

本文根据复垦利用流程及复垦业务功能需求,结合组件式GIS集成开发技术,基于VS2008与Arc En-gine平台,采用SQL Server 2005数据库设计并开发了高速铁路大临设施用地复垦利用辅助决策系统。该系统实现了复垦方向优化过程的自动分析、复垦利用参数的动态设定、复垦工程量及投资的自动计算,并在京沪高铁江阴制梁场得到应用,取得了良好的效果。     

Automatic mapping of snow cover depletion curves using optical remote sensing data under conditions of frequent cloud cover and temporary snow

Snow cover depletion curves are required for several water management applications of snow hydrology and are often difficult to obtain automatically using optical remote sensing data owing to both frequent cloud cover and temporary snow cover. This study develops a methodology to produce accurate snow cover depletion curves automatically using high temporal resolution optical remote sensing data (e.g. Terra Moderate Resolution Imaging Spectroradiometer (MODIS), Aqua MODIS or National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR)) by snow cover change trajectory analysis. The method consists of four major steps. The first is to reclassify both cloud‐obscured land and snow into more distinct subclasses and to determine their snow cover status (seasonal snow cover or not) based on the snow cover change trajectories over the whole snowmelt season. The second step is to derive rules based on the analysis of snow cover change trajectories. These rules are subsequently used to determine for a given date, the snow cover status of a pixel based on snow cover maps from the beginning of the snowmelt season to that given date. The third step is to apply a decision‐tree‐like processing flow based on these rules to determine the snow cover status of a pixel for a given date and to create daily seasonal snow cover maps. The final step is to produce snow cover depletion curves using these maps. A case study using this method based on Terra MODIS snow cover map products (MOD10A1) was conducted in the lower and middle reaches of the Kaidu River Watershed (19 000 km²) in the Chinese Tien Shan, Xinjiang Uygur Autonomous Region, China. High resolution remote sensing data (charge coupled device (CCD) camera data with 19·5 m resolution of the China and Brazil Environmental and Resources Satellite (CBERS) data (19·5 m resolution), and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data with 15 m resolution of the Terra) were used to validate the results. The study shows that the seasonal snow cover classification was consistent with that determined using a high spatial resolution dataset, with an accuracy of 87–91%. The snow cover depletion curves clearly reflected the impact of the variation of temperature and the appearance of temporary snow cover on seasonal snow cover. The findings from this case study suggest that the approach is successful in generating accurate snow cover depletion curves automatically under conditions of frequent cloud cover and temporary snow cover using high temporal resolution optical remote sensing data. Copyright © 2007 John Wiley & Sons, Ltd.     

曲率半径对临时支护及核心土的受力影响分析

双侧壁导坑方法开挖面积小,能够将大断面隧道简化为几个小跨度的导洞隧道,增加了隧道的整体稳定性,是特大断面大跨度公路隧道推荐采用的开挖方法之一。但目前并没有统一标准的双侧壁导坑断面的设计方法,核心土临时支护曲率半径形式的设计具有较大的主观性。而实践表明,临时支护的曲率形式对于核心土和导洞的稳定性影响至关重要。以广州龙头山双洞8车道公路隧道为依托,在相同的边界条件下,通过数值计算、实测数据和现场实例,深入分析核心土临时支护的合理曲率形式。其结果旨在为大断面大跨度公路隧道设计的优化提供借鉴和参考。     

浅埋大跨度隧道拆撑对初支安全性影响分析

针对浅埋大跨度隧道拆撑对初期支护安全性影响,对厦门东通道（翔安隧道）陆域CRD法施工段采用现场监测和数值模拟两种方法。对比分析表明,两种方法所得结果吻合良好。研究结果表明,在纵向一次性拆撑长度为10 m的情况下,对拱顶下沉的影响在5 %～10 %左右,初期支护安全系数降低约5 %～15 %,初期支护的安全性受临时支护拆除的影响较小,这为实现隧道的信息化施工提供了依据,也为今后的相关工程积累了经验。     

广谱暂堵技术在准中1区砂岩储层的应用研究

根据准噶尔中部1区块三工河组储层特点，在充分考虑油藏孔喉非均质性的情况下，利用广谱屏蔽暂堵技术进行架桥粒子和填充粒子设计，通过室内实验，进行钻井完井液配方的优选。该技术在准噶尔中部1区块使用后效果明显，渗透恢复率达到95%以上，试验井表皮系数均为负值。