Comparison between responses of reinforced and unreinforced embankments due to road widening

The objective of this work is to compare the responses of geosynthetically-reinforced embankment and unreinforced embankment due to road widening by using the centrifuge model tests and a two-dimensional(2D) finite element(FE) model. The measured and calculated responses of the embankment and foundation exposed to road widening include the settlement,horizontal displacement,pore water pressure,and shear stresses. It is found that the road widening changed the transverse slope of the original pavement surface resulting from the nonuniform settlements. The maximum horizontal movement is found to be located at the shoulder of the original embankment. Although the difference is small,it is clearly seen that the geosynthetic reinforcement reduces the nonuniform settlements and horizontal movements due to road widening. Thus the reinforcement reduces the potential of pavement cracking and increases the stability of the embankment on soft ground in road widening.

Response mechanism for widened pavement structure subjected to ground differential settlement

By the use of a large-scale ground differential settlement simulator, a full-size model test is performed to study the strain response and the deformation behavior of both the wearing course of asphalt cement and the base course of cement-stabilized gravel. Moreover, with the differential settlement at the bottom of the pavement structure as the constraint condition, a plane finite element model is established, which is used to study the stress variation of different pavement layers in response to the differential settlement of varying magnitudes. It shows that, under the effects of the ground differential settlement, the wearing course is subjected to the tensile stress while the base course to the compressive stress and the maximum additional tensile stress and compressive stress occur in the area of 1 m from the splicing joint between the new and the old subgrade. Plastic deformation develops in both layers when the ground differential settlement reaches 14 cm. When the differential settlement at the bottom of the pavement goes up to 1 cm, the maximum additional stress in the surface of the base course will reach 0. 28 MPa, which surpasses 0.276 MPa that is specified in the current specifications as the maximum splitting tensile strength for cement-stabilized base material.

Stress and deformation due to embankment widening with different treatment techniques

A two-dimensional(2-D) finite element(FE) model was developed to analyze the deformation and stress of embankment on soft ground due to widening with different treatment techniques.It is found that the embankment widening induces transverse gradient change due to differential settlements and horizontal outward movements at the shoulder of the existing embankment.Embankment widening also increases the shear stress along the slope of the existing embankment,especially at the foot of slope.The failure potential due to embankment widening may increase with the increase of widening width when the widening width is smaller than 8.5 m,but may decrease with the increase of widening width as the widening width is greater than 8.5 m.The effectiveness of four ground and embankment treatment techniques,including geosynthetic reinforcement,light-weight embankment,deep mixed columns,and separating wall were compared.The results indicate that these treatments reduce the differential settlements and improve the stability.The light-weight embankment has the most effectiveness among four treatments.By using the fly-ash backfill material in widening,the transverse gradient change decreases from 0.5%-1.3% to 0.26%-0.8% and the maximum horizontal displacement decreases from 2.76 cm to 1.44 cm.

Settlement patterns of mountainous half-filled and half-cut widened subgrade with retaining wall

The settlement of widened highway subgrade in mountainous area is not only affected by the interaction between new and existing subgrade, but also seriously restricted by the external retaining wall. Based on the practical engineering of half-filled and half-cut widened mountainous highway subgrade with external balance weight retaining wall(BWRW), a sophisticated finite element numerical model is established. The evolution law of subgrade settlement is revealed during the whole process of new subgrade filling and BWRW inclination after construction. The settlement component of subgrade is clarified considering whether the existing pavement continues to be used. The results show that the additional settlement caused by the BWRW inclination after construction cannot be ignored in the widening and reconstruction of mountainous highway subgrade. In addition, pursuant to the comprehensive design of subgrade and pavement, the component of subgrade settlement should be determined according to whether the existing pavement continues to be used, while considering the influence of BWRW inclination after construction. When the existing pavement continues to be used, the settlement of the existing subgrade is caused by the new subgrade filling and the BWRW inclination after construction. On the contrary, the settlement is only caused by the BWRW inclination after construction.

Analysis of Control Measures for Settlement of Differences on the Problems of Highway Subgrade Widening

The study mainly discusses the issues of the settlement of differences that occurs in the process of highway subgrade widening. Firstly, it briefly introduces the settlement of difference and its harms;then it analyzes the mechanism of settlement of differences in the process of difference widening, including four aspects: the new and old roadbeds themselves, design, construction and other links;finally, based on the above analysis of the mechanism, it discusses the corresponding control measures, mainly proposing these suggestions as followings: the use of lightweight materials, the foundation treatment, the cut slope excavation steps, and the strict control of the degree of compaction, etc. The paper is expected to provide some theoretical basis for the control measures of highway subgrade widening settlement of difference.

一种新型山区道路拓宽方案研究

针对山区低等级道路拓宽工程,尤其是一侧高路堑、另一侧高陡崖或高陡路基的路段,提出一种外侧枕梁支撑、内侧锚杆拉结的悬臂承载梁新型拓宽方案,以某路基拓宽工程为例,介绍其结构型式,并进行承载性能研究。结果表明:新型拓宽方案结构合理,强度、刚度及稳定性满足相关规范要求;适当加深外侧枕梁深度,可明显提高承载稳定性,较差的岩体建议采用地下连续墙或桩基础;内侧预应力锚杆强度及其与承载梁的连接尤为重要,是控制承载梁在外侧偏载作用下结构稳定的关键;限位装置是确保整体稳定、防震、防止承载梁不滑脱、锚杆不受剪的关键。

乡村水泥路面拼接窄长加宽板受力特性分析

福建省农村公路水泥路面多为4.5m×5m的单板单车道,随着交通量的增加,多加宽2m成为双车道。建立有限元模型,研究新旧板缝间摩擦系数、拉杆间距、土基模量等参数下水泥板加宽2m前后的受力变化,发现新旧路基模量差对板底拉应力影响最大,拉杆间距影响不大,但对板缝两侧弯沉差影响最大。

软土条件下的公路拓宽工程路基沉降控制技术

针对软土路基在公路拓宽施工中遇到的问题,从土质分析入手,探讨了路基、路面沉降的原因和影响因素,及不同控制路基沉降技术手段的优缺点。通过实验研究,提出利用水泥搅拌桩加固方式实现对路基沉降的控制,通过有限元法分析不同搅拌桩参数对于沉降效果的影响,仿真结果证明,搅拌桩的长度、间距、模量以及路堤的填土速率等,均会对路基的沉降产生影响,需要在实际的施工工艺中,对参数和工期、成本等加以权衡,以保证获得最好的路基沉降控制水平。

高速公路涉路拼宽施工对驾驶员心率增长率的影响

文中以浙江甬台温高速温州东—塘下段拼宽涉路工程为依托开展实车试验.利用Physiolab无线心理仪采集驾驶员心生理数据,研究驾驶员心率增长率指标变化特征.结果表明:涉路工程作业区路段比一般路段的驾驶员心率增长率均值和变化区间长度分别提高了16.34%、20%,并基于突变理论得到心率增长率安全水平阈值为35%,由此确定基于驾驶员心生理影响的涉路施工作业区风险路段.为驶入涉路工程作业区路段前200 m和驶出作业区后120 m.通过对涉路工程作业区六个区段的驾驶员心率增长率均值和标准差进行分析比较发现驾驶员心率增长率在工作区、上游过渡区、以及警告区变化更明显,均值较安全水平阈值分别高出18.56%、4.81%、3.52%.

单向双车道立交匝道路面加宽理论计算及仿真分析

为确定不同条件下单向双车道立交匝道的加宽值,本文对比分析了中国、日本及美国规范中关于加宽值的计算思路,提出较为合理的单向双车道匝道加宽计算方法,并分析设计速度和曲线半径对加宽值的影响,对立交细则中Ⅱ型匝道加宽值进行了修正,使用仿真软件Vissim分析不同交通环境下行车道宽度对通行情况的影响,最后结合工程实践,详细介绍了加宽计算方法,可为单向双车道立交匝道路面加宽提供参考。

城市道路拓宽改造横断面选型要点分析

以辽宁省大连市高新园区城市主干路红凌路拓宽工程为例,针对道路拥堵严重的问题,采用通行能力分析的方法,并考虑用地限制、避让管线、保留树木等因素,研究城市道路拓宽横断面的选型,并给出了具体示例。道路拓宽根据实际情况分路段选择最适宜的横断面形式,能够在较好地改善道路交通拥堵问题的同时,降低工程难度,提高工程经济性,达到可持续发展的目标。

道路旧路拓宽新旧路基变形协调综合处治技术

公路作为现代交通运输的重要组成部分,对国家经济发展和人民生活起着至关重要的作用。然而在道路旧路拓宽过程中,常常会出现一系列由于各种原因造成的路面下部结构损坏或失效的现象,包括路基塌陷、路基沉降、路基侧滑等.严重影响了公路的使用寿命和安全性。为了确保公路的长久运行和安全,必须深入了解这些病害的成因,并采取相应的预防对策。基于此,本文结合工程实例,首先对道路旧路拓宽过程中常见的路基病害进行分析,并总结了常用的路基病害预防对策,希望能对该问题的解决起到一定帮助。

城市道路圆曲线加宽设计的计算方法及参数优化

在城市道路路线规划设计中,由于机动车在圆曲线道路行驶时机动车前后车轮、内外半径各不相同,前轮外侧圆曲线半径最大,而后轮内侧半径最小且逐渐向内弯曲。为此,文章分析了城市道路圆曲线加宽设计中的3种具体情况:加宽后内侧车道中心线与之前道路中心线不重叠、加宽后车道两边道路曲线不协调、加宽后车道过渡路段车道不顺利衔接过渡问题,从而更加科学合理地计算规律、优化其参数,为相关设计提供解决问题更优方法。

拓宽公路差异沉降问题的研究现状与成果综述

为系统地了解拓宽公路工程中差异沉降问题的研究现状和成果,有序梳理1997—2021年间的576篇相关文献,总结拓宽公路差异沉降问题研究的发展历程、主要研究内容和实际工程案例。归纳拓宽公路差异沉降的影响因素,提出按照内因、外因、直接因素和间接因素进行分类的方法;整合各因素对差异沉降曲线的影响规律和特征,建立差异沉降双向变化型、单向局部变化型和单向整体变化型三种曲线概化模型;总结差异沉降对路面结构层应力的影响规律;确定新旧路面拉应力的控制层位置,建立差异沉降控制标准计算的概化思路;整理差异沉降减控技术的种类,比较各减控技术的适用性和优缺点。基于研究现状,展望新旧路基顶面差异沉降的研究方向。

公路市政化改造与路桥拓宽技术应用

随着城市化进程的加快和汽车保有量的急剧增长,原有的公路和桥梁设施已经不能满足当前的交通需求,道路拥堵、交通事故和城市的环境问题日益凸显,严重制约了城市的经济社会发展。而公路市政化改造和路桥拓宽不仅是提高城市道路通行能力、解决交通拥堵的有效手段,还关乎城市的可持续发展、生态环境保护及居民的生活质量,掌握先进的技术方法,可以为这些改造工程提供科学、合理的指导,提高工程效益,降低施工成本和风险。本文就针对公路市政化改造及路桥拓宽技术展开论述,以供参考。

市政道路路基拓宽施工技术分析

为解决现代建筑业发展难题,本文将以市政道路工程为背景,围绕路基拓宽施工展开研究,首先阐述市政道路路基工程施工特点,然后论述市政道路路基拓宽的施工技术应用策略,最后从多方面出发,提出关于提高市政道路路基拓宽施工质量的有效举措,旨在发挥施工技术优势,完善市政道路路基施工模式,持续优化路基拓宽施工效果。

市政道路路基拓宽施工技术

市政道路路基拓宽施工的难度较大,为达到施工效果,相关人员需准确把握路基拓宽施工的特点,优选技术,合理控制施工操作。未来的市政道路建设中需继续研究路基拓宽的新技术,构建科学的施工技术体系。基于此,本文重点分析了市政道路路基拓宽技术的类型及要点,以期为同类型项目提供指导与借鉴。

公路改扩建为城市道路的横断面设计探讨

针对公路改扩建为城市道路需要考虑众多因素的问题,以广州市南沙区番中公路改造为市政路的断面选择为工程实例,对横断面设计的思路进行了探讨。同时,结合项目实际,分别对道路与公路的使用功能差异,以及现状道路、绿化、市政管线等控制要素进行了方案比选论证,为公路改扩建为城市道路的横断面设计提供参考。

市政道路改造拓宽中的基础施工技术分析

实施拓宽改造是提升市政道路性能的有效举措,也是解决城市交通拥挤问题的重要手段。文章以某市政道路项目为例,对道路改造拓宽项目的关键技术展开讨论,总结市政道路改扩建项目施工经验。根据道路后期运行情况,道路改造拓宽施工技术的应用能有效提升市政道路性能,具有较高的推广价值。

拓宽道路工后差异沉降控制标准

为了防止道路拓宽工程中过大的差异沉降引起路面纵向裂缝和路基失稳,以河南安新(安阳—新乡)拓宽道路工程为实体依托工程,采用有限元方法,从路面结构对差异沉降的力学响应、平整度对差异沉降指标的要求、行车荷载对差异沉降指标的要求等方面,研究拓宽道路工后差异沉降控制标准,并对差异沉降进行了分级。结果表明:以路面结构的力学响应考虑差异沉降控制指标较好,并以4 cm作为差异沉降控制标准的低限,以9 cm作为差异沉降控制标准的高限。