方钢管混凝土柱-钢梁平面框架耐火性能研究

建立了局部火灾下多层多跨矩形钢管混凝土柱-钢梁平面框架温度场和力学性能分析的有限元模型。在考虑楼板影响的基础上,研究了保护层厚度不同时钢管混凝土框架结构的温度场分布规律。研究了不同受火工况条件下钢管混凝土框架结构的变形和破坏规律、耐火极限状态、受火梁的内力状态以及结构耐火极限的规律。分析表明,梁保护层厚度影响钢梁温度分布形式;火灾下,框架结构发生了受火梁的整体屈曲破坏。     

建筑围护结构节能与防火体系构建

从围护结构节能与防火一体化思路出发,提倡钢筋混凝土结构保温一体化建筑体系和砌体结构保温一体化建筑体系;尤其主张在我国建筑工业化全面升级的基础上大力开发与推广保温型混凝土预制装配化技术,统一建筑模数,实现标准化与多样化;针对预制装配化保温型混凝土在梁、构造柱等容易出现的冷、热桥问题的部位,创新式提出以相变储能材料与建筑结构相融合来提高建这些部位的热工性能,减少温度梯度;从系统上做到保温与建筑同寿命、免维护、工序少,工期短、耐火等,从而真正实现低碳,构建建筑围护结构节能防火一体化建筑体系。     

地下城市综合管廊的抗火构造与消防设计

综合管廊作为现代化城市的基础设施,能够从根本上解决管线埋设或架立引起的挖掘道路、影响交通、破坏景观等问题。提高道路和公用管线的管理水平,有效利用地下空间,提高防灾能力,是现代化都市的必然要求。本文从管廊的构造、抗火设计要求、管线布置、消防系统等方面出发,对地下城市综合管廊的设计提出了一些具体的建议。     

Forest cover change assessment in conflict-affected areas of northwest Pakistan: the case of swat and shangla districts

This study examines the spatial and temporal forest cover changes in Swat and Shangla districts to understand the deforestation pattern in context of the recent security conflict in these districts. We used multi-resolution satellite images to assess the long term deforestation from 2001 to 2009 and also to identify episodic forest cutting areas appeared during the conflict period of Oct. 2007 - Oct. 2008. There are only 58 ha of deforestation identified during the conflict period while 1268 ha of gross annual deforestation were assessed during last eight years. Most of the deforestation patches persist around the administrative boundaries at sub-district levels (tehsils) which can be attributed to ambiguity in unclear jurisdiction between the forest official. The results highlight that the forest cutting appeared in Swat and Shangla during the conflict period is not as significant when compared with the long term deforestation pattern in the area. On the one side the results of the study are supportive to the picture that emerges from international studies which report high rate of deforestation in the country and on the other side it negates any relation between the security situation and the increasing deforestation in the north western Pakistan. The study concludes that deforestation assessments require verification by independent sources of data, such as satellite imagery to improve our understanding of deforestation processes.     

单层带支撑异形柱框架的高温性能研究

针对单层异形柱框架,通过高温数值分析,考察了支撑设置和受火位置对结构高温变形及内力的影响。研究结果表明：对于单层多跨异形柱框架,当只有一端有支撑跨时,会在一定程度上增大另一端的边节点水平位移和边柱侧向变形,对结构整体抗火不利;当左、右两端均有支撑跨时,非支撑跨在火灾作用下的梁轴力比很大,升温后期可能因梁跨中竖向位移急剧增大而发生破坏。基于上述研究结果,给出了4类单层带支撑异形柱框架火灾行为的初步判定方法。     

铁路隧道火灾中烟气逆流层长度的研究

以狮子洋隧道为工程背景,对不同火源热释放速率、不同通风风速、不同坡度及不同断面当量直径情况下的火灾进行了数值模拟。分析了隧道烟气逆流层长度的变化规律,并对模拟数据进行了拟合。结果表明,隧道烟气逆流层长度与通风风速、火源热释放速率、隧道断面当量直径的自然对数值拟合均符合直线关系,呈递增或递减变化;坡度对烟气逆流层长度的影响随通风风速的增大而减弱。在分析烟气逆流层长度变化规律的基础上,建立了烟气逆流层长度与火源热释放速率、通风风速及断面当量直径的关系式,通过对数据拟合获得了烟气逆流层长度公式,该公式推导合理,并有所创新。     

煤田火区环境影响综合评价指标体系与评价方法

在研究煤田火区对自然-社会经济系统影响的基础上,提出了煤田火区环境影响综合评价指标体系的构建思路,建立了煤田火区环境影响评价的一般性指标体系,包括5级32个指标。以内蒙古乌达煤田火区为实例,论述了煤火环境影响综合评价的实施过程。根据煤田火区特征,在一般指标体系框架内确定了23个评价指标,采用层次分析法与综合指数法相结合,建立了火区环境影响综合评价公式。评价结果表明,乌达煤田火区对环境的影响为较严重水平,与定性分析结果相符。     

中国园林叠山的传承与发展——北京奥林匹克森林公园叠山之探讨

我国造园叠石世家“山石韩”已传承百余年,其第四代传承人韩建中创办了北京南山石韩园林绿化工程有限公司并完成了北京奥林匹克森林公园“林泉高致”和“天境”两大主要假山景观工程的设计与施工。本文介绍了这两处假山景观的设计立意和营造技巧,从实例出发体现出我国园林叠山的传承与发展。     

How green was my valley: forest canopy density in relation to topography and anthropogenic effects in Manipur valley,India

Forest canopy density (FCD) is a major factor in the evaluation of forest status and is an important indicator of possible management interventions. The study uses the FCD model with Landsat TM and Landsat 8 OLI images to assess canopy density in India’s Manipur valley and surrounding hills. Normalized difference built-up index (NDBI) was used to extract built-up areas and population density was retrieved from LandScan data, while elevation and slope were obtained from ASTER DEMs (30 m). Four types of canopy density were delineated with crown cover above 71%, 41–70%, 11–40%, below 10% and areas with no canopy cover, that is 0%. A sharp decline in forest area occurred during 1989–2016 at a rate of loss of 2.9 % year-1 with an average rate of deforestation of 3051 ha year-1. Dense forests exhibited remarkable degradation, especially towards the central valley. The variation in the topographical (elevation and slope) gradient resulted in significant differences in the canopy density over the study area barring some hill slopes. Population pressure and various developmental activities in recent decades led to forest degradation in this fragile yet rich Eastern Himalaya biodiversity hotspot.     

Forest Fire Alert System: a Geo Web GIS prioritization model considering land susceptibility and hotspots – a case study in the Carajás National Forest,Brazilian Amazon

To increase the monitoring potential of forest fires, an alert classification methodology using satellite-mapped hotspots has been established to help forest managers in the prioritization of which hotspot to be verified in the field, thus potentially improving the distribution of fire-fighting resources. A computer application was developed based on web-distributed geographical information technology whose main function is to interact automatically generated satellite hotspots and risk areas indicated in fire-susceptibility maps and classify them into five alert levels. The location of the hotspots is available continuously every 4 h, and a susceptibility map is produced daily through map algebra algorithm, which uses static (topography, vegetation and land use) and dynamic (weather) variables. Every process runs through automated geoprocessing routines. The methodology was tested during the dry period of 2007 in the Carajás National Forest, in the Brazilian Amazon, within an area of 400,000 ha. It is a critical area constantly threatened by fires caused by invasions and deforestation owing to intense agribusiness advances and mining activities in its surroundings. This situation results in observations of many hotspots inside the study area for the same day and almost the same time period, in places of extreme opposites, demanding complex rapid analysis and hindering the decision of the displacement of fire-fighting teams. Further, a major mining company operates within the National Forest area, maintaining actions of protection as part of its environmental mining license. Results are presented under three aspects: (i) the credibility of the daily susceptibility map (algorithm), which showed strong correlation between areas of greatest risks and the confirmed forest fires; (ii) the reliability of hotspots (alert levels), confirming 71% of fires; (iii) accuracy in the decision of which hotspot to be checked, which revealed the same number of verifications at different alert levels, 82% confirmed alert 5 hotspots (maximum) and only 50% from alert 1 (minimum), resulting in faster fire-fighting actions, minimizing burned areas and, in some cases, allowing fire control before its spreading. Therefore, the methodology demonstrated that GIS routines are able to determine the relationship between a reality-based, interpreted susceptibility map of the area and satellite-generated hotspots, highlighting the ones of highest hazard level through the alert classification, becoming an important tool to help decisions from the fire-control center, especially for high-risk regions. The methodology may be extrapolated to other forested areas.