基于红外热成像技术烃类火灾下沉管隧道开裂分析*

为了研究烃类火灾下沉管隧道的开裂深度,建造沉管隧道缩尺模型,采用HCinc升温曲线在沉管隧道左、右两侧孔内同时开展明火试验。在沉管隧道火灾试验过程中,利用热电偶和红外热像仪测量沉管隧道的温度场变化,利用红外热像仪对混凝土裂缝位置的温度变化进行监测。基于混凝土内水分迁移原理,结合混凝土裂缝中水和水蒸气的温度变化及混凝土内温度场分布,推断出在点火95 min时,混凝土裂缝开展深度超过150 mm。研究结果表明:在沉管隧道内部发生火灾的情况下,受火侧受热膨胀容易导致沉管隧道外侧混凝土受拉开裂,在沉管隧道抗火设计中,建议考虑内外侧温差导致的混凝土开裂问题。     

Identification of non-value adding (NVA) activities in precast concrete installation sites to achieve low-carbon installation

The lean production philosophy has been applied in the construction industry to reduce waste and increase efficiency. It is until recently that the lean philosophy has proven to be effective to meet the challenges of sustainable development. Many studies have shown that lean philosophy can be applied in precast concrete factories to lower inventory, reduce waste and increase efficiency. However, the precast concrete installation cycle should not be overlooked following a life cycle perspective. This study adopts a weighted factor model comprising 30 contractors in the Singapore construction industry and a case study. Construction site layout management practices are investigated using the weighted factor model. Strategies to improve the construction site layout are presented in a case study. The results indicated that there are many non-value adding activities in the site layout management practices that contribute to an increase in the carbon emissions level. Little consideration of green building materials, improper specifications of the precast concrete products, lack of an uninterrupted workflow, and inaccurate estimation of seem to be the most important ones. The results provide good practice guidance and can be used as a checklist for contractors to identify the NVA activities in the installation sites to achieve low-carbon installation. The results will also be useful for regulatory agencies to provide recommendations for contractors to improve the installation procedure and reduce carbon emissions.     

Non-point source analysis of a railway bridge area using statistical method：Case study of a concrete road-bed

In an effort to protect the quality of the water system, interest in non-point source pollution is increasing. Recently, studies of non-point sources pollution are continuing in relation to various land- use areas, but such studies have not been fully conducted in railway facility sites. Using monitoring data of railway bridge area with concrete road-bed, the runoff characteristics, pollutant unit loads, and first flush criteria were assessed. Railway bridge area with concrete road-bed typically show the first flush effect, and the pollutant unit load was determined to be higher than other public facilities areas. Further, the first flush criteria show an effective rainfall amount of 7 mm. In other words, from the runoff of railway facilities, considerable amounts of non-point source pollutants are occurred, indicating the need to create best management practices which are adequate for railway facility sites.     

海洋混凝土结构表面防护涂料环境适应性评价研究进展

综述了岛礁混凝土结构表面防护涂料海洋环境适应性评价（老化）研究进展,对表面防护涂料海洋环境适应性评价中试验设计、控制因子设定、试验方法选择、评价指标确定等环节中存在的问题进行了讨论,认为只有在认真梳理单环境因子对涂料作用机理的基础上,对它们进行合理设定,才能有效提高加速试验结果和自然暴晒老化试验结果的相关性。     

极端降雨条件下透水水泥混凝土路面削流除污试验研究

通过试验,对极端降雨条件下透水水泥混凝土路面在削减洪峰流量、径流总量以及去除污染物的效果进行研究。试验表明,在降雨历时60 min,降雨量为110,135,163 mm的情况下,透水水泥混凝土路面削减径流总量为55%~69%,削减洪峰流量为55%~63%;对SS、COD、TN、TP的去除率分别为82%~95%、58%~78%、31%~74%、59%~80%。结果表明,在极端降雨情况下,透水水泥混凝土路面在削流除污方面的效果较好,且与一般降雨条件下的除污效果相近,因此在暴雨情况下,也可产生较好的环境效益,表明其具有气候普适性,是一种良好的海绵城市建设技术。     

某桥墩承台病害分析与处理

桥墩病害的正确分析处理,事关桥梁的安危。介绍了某桥墩承台病害,分析了产生病害的主要原因是混凝土碱骨料反应。据碱骨料反应产生的条件,提出了桥墩承台病害采用优料加大截面隔绝法的处理方案,经由实施,使桥梁重获新生。所提桥墩承台病害处理方案正确,处理效果良好,对类似桥墩的分析处理具借鉴意义。     

爆炸荷载作用下方钢管混凝土柱的动力响应及破坏机理

方钢管混凝土柱是被广泛采用的组合构件之一.爆炸发生时产生的爆炸冲击波可能会对框架结构内部的方钢管混凝土拄造成严重破坏,然而目前对其动力响应及破坏机理的研究成果相对较少.本文采用有限元分析软件ANSYS/LS-DYNA对爆炸荷载作用下方钢管混凝土柱的动力响应和破坏机理进行了研究分析.建立了方钢管混凝土拄实体有限元模型,其...     

圆钢管轻集料混凝土梁与混凝土桥墩连接节点试验研究

为了解决圆钢管轻集料混凝土梁与混凝土桥墩的整体连接问题,共设计了穿心钢筋、穿心钢筋加弯矩传递板和穿心工字钢3种节点连接形式,采用拟静力试验研究了刚节点在低周反复荷载作用下的抗震耗能性能。试验结果表明,3种节点都具有良好的抗震耗能性能,等效粘滞阻尼系数都超过了钢筋混凝土结构要求的0.1,延性系数都大于规范规定的2;在节点屈服以后,3种节点仍然具有一定的承载力,其中穿心钢筋和穿心工字钢节点的延性系数和等效粘滞阻尼系数基本相同,穿心钢筋加弯矩传递板较其他2种刚节点稍差。     

建筑垃圾再生骨料生产工艺及应用研究

采用进口移动式破碎-磁选-筛分设备,将混凝土类建筑垃圾加工成再生骨料,并掺入制备混凝土、干混砂浆、道路无机混合料。检测结果表明,再生制品性能可满足使用要求,再生骨料替代天然骨料比例可达到50%以上。     

乌鲁木齐地区再生骨料混凝土的应用初探

再生骨料混凝土的研究和应用能解决日益发展的建筑业带来的环境问题,通过对乌鲁木齐地区建筑业进行调研,具体分析了乌鲁木齐地区废弃混凝土的现状,提出其再生骨料混凝土技术在乌鲁木齐地区推广应用中存在的问题,进行了再生骨料混凝土应用的技术经济可行性分析,并对乌鲁木齐地区再生骨料混凝土的应用提出相应对策。