Reduced weed growth with different paving constructions

The recent phaseout of herbicide use on public pavements in Flanders has triggered the development of alternative weed control strategies. Besides the search for effective non‐chemical curative methods, there is also a need for strategies that prevent or reduce weed growth on pavements. In this study a paving experiment was set up under a rain shelter to investigate the effects of four construction factors on weed growth: joint filling material, joint width, organic pollution of the joint filling material and type of bedding layer. Paving mini‐plots were oversown with a mixture of dominant, hard‐to‐control weed species found on pavements. The inhibitory effect on weeds was determined by examining initial weed density and weed coverage over a 2‐year period. More weed growth was found in pavings with wide joints and organically polluted joint filling materials. High permeability of the bedding layer resulted in higher weed cover. The coarse‐grained filling materials and the sodium silicate‐enriched sand Dansand^® were associated with less weed cover than the fine‐grained filling materials. Our results show there is potential for preventing weed growth using suitable paving materials and appropriate high‐standard construction and maintenance of pavements.     

Optimal Selecting Model of Uncertainty Measurement for Asphalt Pavement Structure

Scientific method was necessary for road decision maker to select high cost effect ratio pavement structure scheme. According to the fact that many uncertain knowledge and information existed in the process of evaluating the expressway asphaltpavement structure schemes, an evaluation model of pavement structure schemes based on uncertainty measurement was put forward;This method implemented ordered division of assessment space,and could recognize and rank different schemes by comprehensive measurement matrix of multiple indexes. three typical design programs of expressway asphalt pavement structure were evaluated by that model.It is shown that the assessment can objectively reflect the comprehensive performance of asphalt pavement structure ,which provides a new method and way for evaluation of pavement structure schemes.     

Study on Mechanical Properties of Cement Concrete Pavements

The study of the mechanical properties of cement concrete pavements is the base of the structural design of pavement. The existing mechanical models, such as elastic plate system, layered elastic system and so on, are systematically presented. The limitations and merits of various mechanical models are discussed at the same time. The development process of the solution methods for the study on mechanical properties of cement concrete pavements is also presented. The development trend of the study on pavement mechanical properties is given in the end.     

刚性路面板单体性热屈曲的几何非线性分析

从几何非线性理论出发，建立了混凝土路面板单体性热屈曲的非线性方程，并以椭圆积分的形式给出了路面板的轴力、位移、热应力与变温之间的关系，并对如何准确地定义临界铺设温差作出了建议。文中最后给出了一个算例。     

Determining treatment frequency for controlling weeds on traffic islands using chemical and non‐chemical weed control

Many public authorities rely on the use of non‐chemical weed control methods, due to stringent restrictions on herbicide use in urban areas. However, these methods usually require more repeated treatments than chemical weed management, resulting in increased costs of weed management. In order to investigate the efficacy of four non‐chemical weed control methods and glyphosate treatment, experiments were carried out on traffic islands in the growing seasons 2005 and 2006. Three trial sites were each divided into six treatment areas, which were either treated with glyphosate, flame, steam, hot air/flame, hot water or left untreated. The treatments were carried out at regular, predetermined intervals throughout the growing season in 2004, whereas in 2005 and 2006 how many treatments that were required to keep weed cover below a predetermined acceptance level of 2% were investigated. Percentage weed cover was measured every second week using a 75 cm × 75 cm quadrat divided into 100 squares. On the control areas, a rapid increase in weed cover was observed, whereas weed cover could be kept below 2% by 2–7 treatments per year, depending on control method. On average, the following numbers of treatments per year were required: glyphosate 2.5, hot water 3, flames 5, hot air/flames 5.5 and steam 5.5 treatments. The results demonstrate that the weed control should be adjusted to the prescribed quality for the traffic islands by regularly assessing the need for weed control. They also show that tailored treatments can reduce the number of required non‐chemical treatments per year.     

注浆技术在水泥混凝土路面改造中的应用

本文针对国道G318吴江段水泥混凝土路面改造工程,对水泥混凝土路面脱空板形成的原因进行分析,用弯沉法检测判定脱空板;分析注浆技术处理脱空板的加固机理,并阐述施工工艺和质量检测。     

刚性路面板下脱空的封堵治理

本通过对３０１国道哈尔滨－阿城段改造项目６７２处路面板下和２０座桥头搭板及明涵台背下脱空的封堵治理施工，综合分析研究了灌浆封堵方法治理板下脱空问题，达到充实板底、加固基层、增强支撑、防止地表水入渗冲刷，使之均匀传递荷载的目的，从而大大延长刚路面的使用寿命。通过室内，现场试验与施工研究，提出板下脱空的检测方法，浆的配合比及施工艺。     

冰雪路面车速预估模型的建立

通过冰雪路况对车辆运行速度影响的分析，建立冰睡面对稳态车速的影响系数，采用理论分析与试验验证相结合的方法，修正冰雪路面下世界银行公路建设贷款模型的车速预估模型。     

路面结构极限承载能力分析

针对某公路路面的早期损坏,进行了超载车辆的轴重及其轮胎接地面积和压力的调查.基于实际轴载的作用图式,分别应用弹性层状体系理论和弹性薄板理论有限元法分析了重荷载作用下,该公路沥青路面和水泥混凝土路面结构的力学响应.按照起决定作用的各结构层材料抗拉强度确定两种路面结构类型的极限承载能力,初步建立了分析路面结构极限承载能力的方法.分析结果表明,沥青路面早期损坏的根本原因是过大轴载对路面结构的一次性加载破坏,而不是轴载重复作用的疲劳破坏,按现行规范设计确定的水泥混凝土路面结构的极限承载能力明显高于沥青路面结构的极限承载能力.     

对南京玉兰路水泥混凝土路面结构设计的评价

玉兰路为南京雨花区2002年第三、四季度设计施工的一条水泥混凝土路面。本文结合新的《公路水泥混凝土路面设计规范》(JTG D-2002)对玉兰路路面进行了结构设计评价。