延边地区公路沿线边坡失稳试验分析

延边地区公路沿线分布着大量软岩，其岩性具有强膨胀性，致使这一地区公路边坡出现了多处滑坡现象。为了合理地处理这一工程地质问题，需要认真研究该种软岩的膨胀特性。选取滑坡体软岩为研究对象，定量分析了其自由膨胀率、无荷膨胀率和有荷膨胀率，并具体测定了其膨胀力，探讨了其膨胀率和膨胀力的变化规律，揭示了研究区软岩的膨胀特性，为公路建设中软岩边坡加固参数的选取提供了科学的依据。     

Development of heat transfer and evaporation model of LNG covered by Hi-Ex foam

Natural gas is a kind of clean, efficient green energy source, which is used widely. Liquefied natural gas (LNG) is produced by cooling natural gas to −161 °C, at which it becomes the liquid. Once LNG was released, fire or explosion would happen when ignition source existed nearby. The high expansion foam (Hi-Ex foam) is believed to quickly blanket on the top of LNG spillage pool and warm the LNG vapor to lower the vapor cloud density at the ground level and raising vapor buoyancy. To identify the physical structure after it contacted with LN₂ and to develop heat transfer model, the small-scale field test with liquid nitrogen (LN₂) was designed. In experiment, three layers including frozen ice layer, frozen Hi-Ex layer and soft layer of Hi-Ex foam were observed at the steady state. By characterizing physical structure of the foam, formulas for calculating the surface of single foam bubble and counting foam film thickness were deduced. The micro heat transfer and evaporation model between cryogenic liquid and Hi-Ex foam was established. Indicating the physical structure of the frozen ice layer, there were a certain number of icicles below it. The heat transfer and evaporation mathematical model between the frozen ice layer and LNG was derived. Combining models above with the heat transfer between LNG, ground and cofferdam, the heat transfer and evaporation mathematical model of LNG covered by Hi-Ex foam was developed eventually. Finally, LN₂ evaporation rate calculated by this model was compared with the measured evaporation rate. The calculated results are 1.2–2.1 times of experimental results, which were acceptable in engineering and proved the model was reliable.     

基于改进粒子群算法和元胞自动机的城市扩张模拟——以南京为例

为合理利用多智能体算法解决城市扩张动态模拟问题,基于地理学理论和社会学规律对粒子群算法进行有针对性的改进,提出分段式粒子群算法(SPSO),并结合元胞自动机模拟复杂时空过程的能力,构建出适用于城市扩张模拟的地理元胞自动机SPSO-CA。在SPSO-CA中我们利用多时像的土地利用数据、交通路网数据和地形数据,挖掘出1995~2000年南京城市扩张的土地转换规则。再由此规则实现1995~2008年的南京市城市扩张过程的动态模拟。最后对比SPSO-CA、PSOCA及NULL模型结果得:SPSO-CA总精度86.3%,Kappa系数为0.792,Moran’s I为0.078,PSO-CA总精度83.6%,Kappa系数为0.755,Moran’s I为0.054,NULL模型总精度81.9%,Kappa系数为0.741,真实的Moran’s I为0.072。这表明无论是总精度还是空间一致性,SPSO-CA都优于PSO-CA和NULL模型,即用SPSO-CA模拟城市扩张是可行的。     

含污泥坑生活垃圾填埋场竖向扩容工程稳定沉降分析

为减少生活垃圾填埋场内污泥坑的存在给填埋场后期竖向扩容工程带来的难度,以辽宁省某含污泥坑生活垃圾填埋场为例,对其竖向扩容工程进行了工艺设计和验证分析。根据工程目标和相关规范,合理确定了扩容后填埋场整体平面布置和填埋堆高等参数,选用原位固化技术对污泥进行了加固处理,并确定了处理后污泥的力学参数设计值。使用Geo-Slope软件,建立了扩容后填埋场堆体边坡的计算模型,并分析和评价了3种不同工况边坡抗滑稳定性的影响。基于理正岩土软件,对填埋场垃圾堆体进行了沉降计算,并根据沉降分析结果进一步确定了防渗系统设计方案。结果表明：污泥坑加固处理后,各工况下的垃圾堆体边坡抗滑稳定安全系数均满足规范要求;固化处理后污泥的相关强度等指标均满足垃圾堆体竖向扩容设计要求;防渗系统最大伸长率为0.4%,满足规范要求;防渗结构中设置了抗沉降加筋层,可抵抗垃圾堆体的不均匀沉降。本研究成果可为国内同类型生活垃圾填埋场的竖向扩容工程工艺设计提供参考和借鉴。     

西藏公路建设过程中的生态保护

针对西藏独特的高原生态环境特征，分析了公路建设的生态影响，提出了不同生态系统类型的生态恢复和保护措施。     

试论高速公路营运管理中的环境保护

高速公路的发展为改善交通环境和拉动所在地区的经济建设做出了重大贡献,但不论是在建设阶段,还是在运营阶段,高速公路都会不可避免地对周围的自然生态环境产生直接或间接的影响,并带来一系列的环境污染问题。文章对高速公路营运管理的环境保护中存在的问题作了比较深入地分析与探讨,并初步提出了营运期环境保护工作的重点与措施。     

高速公路对沿途土地利用及景观格局的影响——以内蒙古省道103线蒲滩木刀口到城壕段为例

利用2002年和2006年公路建设前后的两期遥感数据,分析了公路对沿线土地利用和景观格局的影响。结果表明：公路建设使公路用地面积增加了4.10km^2,主要由侵占农业用地和沙地所导致;居民区、森林面积分别增加了1.12km^2和0.08km^2,其余土地利用类型面积有所减少;道路、居民区和森林的景观破碎化指数增加,农田、草地、灌木、沙地和水域下降;景观多样性指数增加,景观优势度降低。     

公路建设项目声环境后评价方法研究及其应用

通过对公路建设项目声环境后评价的概念和目的的讨论，对声环境后评价的主要内容作了较系统的研究，提出了公路建设项目声环境后评价的方法，重点介绍了声环境后评价的监测与调查和验证分析的方法，并将其应用到深汕西高速公路的环境影响后评价之中。     

水资源约束下西北干旱区城市扩张特征与变动趋势分析——以西陇海兰新经济带城市为例

论文以西北干旱区陇海兰新经济带城市为例,分析了城市水资源利用状况及其短缺程度,认为绝大多数城市“缺水又费水”,城市发展具有明显的“旱生性”。在水资源约束下,西陇海兰新经济带城市的发育程度远远落后于东部地区城市,也落后于全国城市平均水平,略好于西部地区城市,但明显好于西北地区城市,城市扩张的总体特征表现为以总量扩张为主,“农转非”空间和用地拓展空间大,以高耗低效扩张为主,水土资源投入产出效益普遍低下,城市发展处在主要依靠资源开发拉动经济增长的低级阶段,扩张质量有待提高。城市发展具有明显的外部推动性。未来20a,在水资源短缺的继续约束下,经济带城市扩张步伐将比较缓慢,扩张幅度将不会有大的变化。表现为将净增城市非农业人口6.31×106人,城市化水平将提高到35.97%,20a共净增7.21%,特大城市数量将保持西安、兰州和乌鲁木齐3个不变;大城市从无到有,将建成宝鸡、咸阳、铜川、天水、石河子和库尔勒6个;中等城市数量将会显著增加,由2000年的10个增加到2020年的14个,在不考虑“县改市”的前提下,小城市的数量将会进一步减少。为了确保经济带沿线城市的有序扩张,建议在城市建设过程中以人为本,以水为生命线,以经济发展为动力,以城市规划为法定依据。     

Efficacies of roadway safety improvements across functional subclasses of rural two-lane highways

Introduction

Highway crash occurrence is a leading cause of unnatural deaths, and highway agencies continually seek to identify engineering measures to reduce crashes and to assess the efficacy of such measures. Most past studies on the effectiveness of roadway improvements in terms of crash reduction considered all rural two-lane sections as a single category of roads. However, it may be hypothesized that the differences in the mobility and accessibility characteristics that are reflected in (and due to) the different design standards between different functional subclasses in the rural two-lane highway system can lead to differences in efficacies of safety improvements at these subclasses. This paper investigates the efficacy of roadway improvements, in terms of crash reduction, at the various subclasses of rural two-lane highways.

Methods

An empirical analysis of safety performance at each of the three subclasses of rural two-lane highways was carried out using the negative binomial modeling technique. For each subclass, crash prediction models were developed separately for the three levels of crash severity: property-damage only, injury, and fatal/injury. The crash factors that were considered include lane width, shoulder width, pavement surface friction, pavement condition, and horizontal and vertical alignments. After having developed the safety performance functions, the effectiveness (in terms of the extent of crash reduction, for different levels of crash severity) of highway safety enhancements at each highway subclass were determined using the theoretical concepts established in past literature. These enhancements include widening lanes, widening shoulders, enhancing pavement surface friction, and improving the vertical or horizontal alignment.

Results and Conclusion

The study found that there is empirical evidence to justify the decomposition of the family of rural two-lane roads into its constituent subclasses for purposes of analyzing the effectiveness of safety enhancement projects and thus to avoid underestimation or overestimation of benefits of safety improvements at this class of highways.