黄土高原典型小流域道路特征及影响因素

通过GPS野外实测黄土高原纸坊沟小流域的道路特征,在GIS空间分析等方法支持下研究了流域内各级道路的分布规律。研究表明:黄土高原道路可分为4级,2级以下的土路是小流域的代表路型。各级别道路总长度都随级别增大而增加且累计总长度与道路级别线性相关,道路平均长度和密度则随级别增大而减小。道路网系和流域水系在结构规律上具有一定的相似性。不同级别道路分布范围受地形特征影响不同。爬坡道路坡度与地表坡度之间存在线性回归关系,且次级道路分布受主路控制;典型爬坡路在大于25°坡度范围内多呈"之"字形弯曲,随坡度的减小道路弯曲跨度和与等高线夹角增大。研究结果有助于定量模拟黄土高原地区道路分布特征,并为土壤侵蚀模型中道路影响因子的确定提供参考。     

山区道路泥石流工程防治原则与模式

绕行（避让）或穿越是道路面对泥石流灾区两种传统的处理方式。绕行就是远离灾区,穿越有从流通区或从堆积淤埋区通过两种模式。在淤埋区通过包括地上桥梁（忌用涵洞）和地下隧道两种模式。地上模式中还有从扇顶、扇腰或扇缘通过三种模式可供选择。这些原则与模式均与泥石流性质、规模和公路级别息患相关。本文对这些模式进行了对比研究,最后提出了道路泥石流工程防治的原则与模式。     

Investigations in Kenya and Malawi using as-dug laterite as bases for bituminous surfaced roads

Summary In Kenya 1974/5 and in Malawi 1984/5 trial sections of bituminous-surfaced low volume roads were constructed using as-dug laterite in place of stone or stabilized material as a base course.The laterite did not conform with any accepted specifications but performed equally well when compared with adjoining sections of road using stone or stabilized material as a base.The construction procedures employed are described. A period of 4–6 weeks between the compaction of the base and its surfacing is considered essential if the road is to perform satisfactorily. During this period it is exposed to the weather and traffic or to periodic watering and rolling. This treatment fills any cracks with dust or mud and closes them by the kneading action of rubber-tyred traffic. The bituminous surfacing is applied where the base has dried out to about half the optimum moisture content and is extended about 1.5 m beyond each edge of the carriageway.In 1984, $40000 US per km was saved in Malawi in this way, approximately 70% being in convertible currency without incurring additional maintenance or vehicle operating costs.     

Quantifying the altered hydrologic connectivity of forest roads resulting from decommissioning and relocation

The decommissioning of roads is occurring in many forest environments with the aim of reducing the negative impacts of road runoff on water quality and aquatic habitat. Works associated with decommissioning are expensive so prior assessment of the outcomes of various options is merited. This paper presents a method of quantifying the degree to which a road is hydrologically connected to the stream network and thus the likely impacts of constructing a road of different configurations upon water quality. The method permits comparisons between different road network management options and is useful for assessing the likely result of decommissioning works. Emphasis is placed on quantifying the uncertainty of key performance measures. The procedures developed here are an extension of the probabilistic ‘volume to breakthrough’ model recently formulated by Australian water quality researchers and allow the quantification of road/stream connectivity without the need for extensive parameterization. To demonstrate its utility, the model was applied to an actual road decommissioning and replacement project in southeast Australia. Road areas and drainage outlets were surveyed in the field and flow paths to streams derived from a 1 metre resolution LiDAR based digital elevation model. The results demonstrate that the actual road decommissioning examined in this case was unlikely to reduce runoff to the stream network and that the overall impact of the works in conditions of design storms are likely to result in a net reduction in stream water quality. Copyright © 2007 John Wiley & Sons, Ltd.     

基于路段重要度评价的道路网自动制图综合研究

道路网自动综合是GIS研究的重要基础理论问题。顾及道路重要性对路网制图综合的影响,采用基于对偶拓扑的复杂网络理论构建城市路网对偶拓扑模型,并基于该路网模型建立路段重要度评价方法,进而提出一种基于路段重要度评价的路网自动制图综合方法。实验表明,该方法能够有效地完成不同比例尺下路网的自动综合。     

Influences of forest roads on the spatial patterns of human- and lightning-caused wildfire ignitions

Understanding the spatial patterns of fire ignitions and fire sizes is essential for understanding fire regimes. Although previous studies have documented associations of human-caused fire ignitions with road corridors, less consideration has been given to understanding the multiple influences of roads on the fire regime at a broader landscape-scale. Therefore, we examined the difference between lightning- and human-caused fire ignitions in relation to forest road corridors and other anthropogenic and biophysical factors in the eastern Cascade Mountains of Washington State. We used geographical information systems and case-control logistic regression models to assess the relative importance of these explanatory variables that influence the locations of lightning versus human-caused ignitions.We found that human-caused ignitions were concentrated close to roads, in high road density areas, and near the wildland-urban interface (WUI). In contrast, lightning-caused ignitions were concentrated in low road density areas, away from WUI, and in low population density areas. Lightning-caused ignitions were also associated with fuels and climatic and topographic factors. A weak but significant relationship between lightning-caused fire and proximity to gravel roads may be related to fuels near roads or to bias in detection and reporting of lightning-caused fires near roads. Although most small fires occurred in roaded areas, they accounted for only a small proportion of the total burned area. In contrast, the large fires in roadless and wilderness areas accounted for most of the burned area. Thus, from the standpoint of the total area burned, the effect of forest roads on restricting fire size is likely greater than the impact of roads on increasing fire ignitions. The results of our study suggest that roads and their edge effect area should be more widely acknowledged as a unique type of landscape effect in fire research and management.     

Optimization strategies for sediment reduction practices on roads in steep,forested terrain

Many forested steeplands in the western United States display a legacy of disturbances due to timber harvest, mining or wildfires, for example. Such disturbances have caused accelerated hillslope erosion, leading to increased sedimentation in fish‐bearing streams. Several restoration techniques have been implemented to address these problems in mountain catchments, many of which involve the removal of abandoned roads and re‐establishing drainage networks across road prisms. With limited restoration funds to be applied across large catchments, land managers are faced with deciding which areas and problems should be treated first, and by which technique, in order to design the most effective and cost‐effective sediment reduction strategy. Currently most restoration is conducted on a site‐specific scale according to uniform treatment policies. To create catchment‐scale policies for restoration, we developed two optimization models – dynamic programming and genetic algorithms – to determine the most cost‐effective treatment level for roads and stream crossings in a pilot study basin with approximately 700 road segments and crossings. These models considered the trade‐offs between the cost and effectiveness of different restoration strategies to minimize the predicted erosion from all forest roads within a catchment, while meeting a specified budget constraint. The optimal sediment reduction strategies developed by these models performed much better than two strategies of uniform erosion control which are commonly applied to road erosion problems by land managers, with sediment savings increased by an additional 48 to 80 per cent. These optimization models can be used to formulate the most cost‐effective restoration policy for sediment reduction on a catchment scale. Thus, cost savings can be applied to further restoration work within the catchment. Nevertheless, the models are based on erosion rates measured on past restoration sites, and need to be updated as additional monitoring studies evaluate long‐term basin response to erosion control treatments. Copyright © 2006 John Wiley & Sons, Ltd.     

The effects of logging on frequency and distribution of landslides in three watersheds on Vancouver Island, British Columbia

Three hundred and sixty three landslides in three watersheds that totaled 382 km² were identified from air photographs, beginning at a date that preceded logging to the present. The three watersheds all lie on Vancouver Island; however, they have different precipitation regimes, topography, and amounts logged. Landslide areas in the watersheds varied in size from 200 m² to more than 1 ha. Nearly 80% of the landslides were debris slides; 15% were debris flows, and the remainder primarily rock falls. Following logging, the number of landslides increased substantially in all watersheds although the amount of increase was variable: approximately 11, 3, and 16 times in Macktush Creek, Artlish River, and Nahwitti River, respectively. Other analyses of changes in landslide density also produced highly variable results, with the number of landslides increasing between 2.4 and 24 times. Further, 2–12 times more landslides reached streams following logging activities. Densities for landslides impacting streams increased for the period of record from 1.5 to 10 times following logging activities. The densities were substantially greater where only landslides that reached streams since development began in a watershed were considered. Roads had the greatest spatial impact in the watersheds (compared to their total area), with frequencies determined to have increased by 27, 12, and 94 times for Macktush, Artlish, and Nahwitti, respectively. The results highlight the relative impact of roads and their role in slope stability.     

城市道路设计中关于“人-车-路-环境”信息交互的思考

过去的城市道路设计,人们普遍关注车与路的关系,而经常忽视人与环境这两个因素.本文从城市道路网,平、纵、横设计,道路排水,公交设施,道路景观等方面,在设计中综合考虑"人-车-路-环境"这个大系统.     

压密注浆加固水泥混凝土路面脱空施工工艺与评价方法

文章通过城市地区旧道路的注浆前后弯沉检测分析,说明通过注浆加固可以解决路面脱空,有效提高旧水泥混凝土路面承载能力。同时通过工程实践总结出一套可供工程使用的压密注浆参数、控制和检测措施。