Study on the Construction Technology of Subgrade Pavement in Road and Bridge Settlement Section

With the continuous development of China’s economy,the construction of roads and bridges work has put forward higher requirements.Due to various factors,the long-term use of roads and bridges will produce a settlement phenomenon.Therefore,it is crucial to address settlement issues during the construction of roads and bridges to ensure that the quality of subgrade and pavement construction meets national regulations.This paper introduces the harm of subgrade pavement subsidence,analyzes the causes of subgrade pavement deformation,and discusses the technical points of subgrade pavement construction,hoping to provide some reference for relevant practitioners.

Landscape fragmentation associated with the Qingzang Highway and its influencing factors-A comparison study on road sections and buffers

Many studies have examined the effect of roads on landscape fragmentation.Yet they rarely considered local characteristics of the road and road buffer widths.Therefore,this study that took place in the Qingzang Highway(QH)examined the variations in road buffers and road sections of landscape fragmentation.The QH was divided into 32 sections with 23 buffer areas.Based on the indicators of landscape fragmentation from 1980 to 2018,we found significant spatial heterogeneity between sections and buffers.Generally,landscape fragmentation de-creased with increasing buffer distance to the QH.For different sections,the coefficients of variation between buffers were rather high and significantly different.Therefore,fixed-width buffers may overestimate or underes-timate the spatial scope and influence intensity of a road.The impacts of road sections around provincial capitals,prefecture-level cities and main counties on landscape fragmentation were relatively extensive and formed clus-ters of highly fragmented areas.Geodetector results indicated that natural and anthropogenic factors,such as altitude,climate,distance to major settlements and socioeconomic conditions,could well explain the spatiotem-poral characteristics of landscape fragmentation.Altitude,precipitation and the distance to major settlements had higher explanatory power for landscape fragmentation in permafrost regions,whereas slope and socioeconomic condition had higher explanatory power for non-permafrost regions in Xizang Autonomous Region.

Cellular automation model for analyzing capacity of branch road section

In order to reduce the traffic pressure of urban arterial road with the rational utilization of the branch road,the vehicle meeting behavior on the branch road without divided lane was described,and the cellular automation (CA) model was put forward by introducing meeting behavior to reflect the relation between safe meeting speed and road width.The numerical simulation results depict several relation curves between road section capacity,speed and road width under different directional distributions of traffic flow,as well as the curves between the major and minor direction saturation flow,speed and road width.These relation characteristics indicate that except the one-way road section capacity and speed remaining unchanged,other road section capacities and speeds under different directional distributions increase with the increase of road width.On narrow road,the two-way traffic capacity and speed are less than those of one-way traffic;on wide road,the two-way traffic capacity doubles that of one-way traffic,but their speeds are almost the same.As the directional distribution moves to an even distribution of 50/50,the major direction saturation flows and speeds as well as the minor direction speeds tend to decease,while the minor direction saturation flow tends to increase.

Subgrade and Pavement Design Strategies for Different Road Settlement Sections

The quality of road engineering construction largely determines the road operation safety and driving comfort. However, in road engineering construction, the settlement of subgrade and pavement has always been an insurmountable problem. Therefore, in road construction practice, targeted treatment should be carried out for the sections prone to settlement, and subgrade and pavement design strategies for these settlement sections should be carried out, so as to reduce the risk of settlement and ensure the improvement of road engineering quality and safety.

Technical Analysis of Subgrade and Pavement Construction in Settlement Section of Municipal Road and Bridge Engineering

The construction of municipal roads and bridges is an important foundation for the smooth traveling and transportation.However,if there a reduction in the subgrade and pavement part,the safety and the comfort of the driver will be seriously affected,therefore,reasonable measures should be taken on time to tackle the related issues.The significance of subgrade and pavement construction in the subsidence section,the key points of the construction,and the appropriate control measures that are should be taken in the actual construction,was discussed in this paper.Further,this paper analyzes the availability of the subgrade and pavement construction technology for the municipal roads and bridges,to provide a reference for engineers.

弯道路段货车复杂运动惯性荷载特性与机制研究

弯道路段货车运动惯性荷载具有显著的振荡冲击特性,基于车辆多体系统TruckSim动力学仿真方法结合货车荷载现场试验,定义了5类标准弯道类型和荷载特性表征参数,重点对弯道类型、半径、车速和驾驶行为等因素组合对运动惯性荷载的影响开展了研究。研究显示弯道路段货车运动惯性荷载具有分岔、多种运动模式和振荡效应等复杂特性以及偏载、荷载多向组合和冲击基本特性。分岔特性是弯道路段最重要的荷载特性,与车辆速度、弯道半径和超高存在复杂的耦合关系,且具有临界速度效应。弯道路段车辆存在侧向运动、侧倾运动和横摆运动等多种运动模式,并通过悬架弹簧诱发产生复合运动惯性冲击荷载,对于S型、同向型、反向型和广义型弯道存在纵向加减速、制动运动以及多次摇摆运动,且在出弯后荷载具有振荡效应。分岔行为、偏载和过大惯性冲击是诱发弯道路段过早复杂破坏模式和磨损的主要成因,并给出了荷载分岔计算方法、偏载、竖向和水平侧向冲击系数值域,以期为路面设计和管理提供支持。

丝绸之路河西段聚落空间结构特征与优化策略研究

丝绸之路沿线乡村聚落受到特殊地理环境和多元文化的双重影响,具有重要的文化遗产价值。文章选取典型的丝绸之路河西段肃南县马蹄藏族乡的芭蕉湾村、南城子村、石峰村为研究对象,基于人类聚居学理论,从三维和二维角度运用量化的数理分析方法对样本聚落的空间格局进行系统梳理与分析,总结其形态特征与空间组织规律,发现发展中存在的问题。以此为基础,针对乡村人居环境不断改善提升的需求,有针对性地从“遗传”和“修复”两个层面、“面—线—点”三个层级提出聚落空间结构优化思路。

公铁混合布置大跨度斜拉桥主梁断面形式研究--以赣江公铁大桥西支主桥设计为例

以赣江公铁两用大桥西支主桥设计为例,研究一种适应上层8车道公路、下层对称双线铁路+4车道公路混合布置的主梁断面形式。提出带挑臂双索面箱桁组合断面、带挑臂单索面箱桁组合断面、矩形箱桁组合断面、矩形钢桁梁断面4种主梁断面方案,采用有限元软件分析各方案静动力性能及受力特点,综合考虑方案构造特点、技术指标、工程数量、公铁运营安全、景观效果等,确定该桥选用带挑臂双索面箱桁组合断面。该桥斜拉索最大索力16000 kN,锚固在下层钢箱梁两侧,通过有限元实体分析对锚拉板和钢锚箱式两种索梁锚固形式进行比选研究,钢锚箱形式受力合理、应力水平低、经济性好,设计采用钢锚箱形式。带挑臂双索面箱桁组合断面桥面空间布置合理、下层公铁行车干扰小、梁端竖向变形最小、经济性好,是一种适应公铁混合布置大跨度斜拉桥主梁断面形式。

占道施工影响下区域路网容量计算与关键路段识别方法

为研究占道施工事件对区域路网络容量的影响,基于双层规划理论,构建了考虑路段通行能力约束的区域路网络容量计算模型,并设计了求解算法。通过VISSIM仿真软件,确定了施工区段通行能力基准值,对实际通行能力与各影响因素之间的定量关系进行分析,给出了占道施工条件下实际通行能力计算方法。结合交通流分配结果、边介值、蓄意破坏前后路网效率变化率给出了占道施工期区域关键路段识别方法。最后以哈尔滨市阿城区的路网为案例,通过手机信令数据获取得到出行需求分布,计算占道施工前后的路网容量,并对占道施工期阿城区路网进行了重要度排序。研究表明:初始条件下区域路网络容量为38 445 pcu/h,施工时为36 865 pcu/h,路网络容量值减少了4.1%。

基于行驶舒适性的路桥过渡段差异沉降控制阈值

为解决传统路面结构路桥过渡段差异沉降过大和二次跳车问题,结合路桥工程实践,通过将桥头搭板放置一定深度和设置两级枕梁,并将桥头搭板与枕梁现浇在一起的方式,提出一种刚柔连续过渡的桥头搭板结构,用以改善桥头路基的应力分布及变形;同时为研究不同等级公路的路桥过渡段差异沉降控制阈值,给出量化指标,通过分析桥头跳车作用机理,根据车辆振动系统输入激励与输出响应的关系,建立二维五自由度车辆振动模型,并根据不同等级公路的路桥过渡段处治情况,建立相应的计算模型,编写程序求解人体加权加速度均方根值,根据人体舒适程度分级情况确定不同等级公路的路桥过渡段差异沉降控制阈值。结果表明:高速公路一级公路、二级公路和三级公路的路桥过渡段差异沉降控制阈值为将容许搭板纵坡变化值控制在0.30%~0.40%、0.40%~0.55%、0.50%~0.75%和0.95%~1.35%,四级公路的路桥过渡段差异沉降控制阈值为台阶高度控制在0.05m以内。

道路桥梁过渡段路基路面施工要点分析

针对当前道路桥梁过渡段路基路面施工存在的不足,研究总结了相关的施工要点,并分析了道路桥梁过渡段路基路面施工的必要性及存在的问题。根据分析结果,提出了道路桥梁过渡段路基路面施工的优化措施,包括路基路面的挖掘和压实、路基路面的维护保养、桥梁墩台裂缝加固、建筑隔板增强等。

基于后注浆工艺纵横交错双向预应力装配式道路施工关键技术研究

为了提升我国公路工程装配化建造水平,基于后注浆法对预应力装配式道路设计与施工开展研究工作。从装配化道路结构创新设计、优化工艺流程、质量控制、提高结构耐久性、缩短建造工期、环境保护及推进行业转型发展等方面深化研究,建立了基于后注浆工艺纵横交错双向预应力装配式道路结构技术体系,采用了“纵横双向格构梁设计,双向交叉预应力,叠合板倒置支承工艺,后注浆法封孔”技术方案,整体遵循“模块化设计,分区段吊装,双向预应力张拉与封锚,后注浆施工”原则,技术方案经专家论证,可行有效,对推动我国公路工程装配化施工具有显著应用价值。

高速公路路桥过渡段施工技术研究

高速公路路桥过渡段的差异沉降严重影响行车安全性和舒适性,所以深厚软土路段路桥过渡段的工后沉降山处理尤为重要。针对软基处理软土区软基深、难度大、造价高的特点,文章根据辽宁省大连市甘井子区某沿海高速公路建设工程实例,对高速公路路桥过渡段的施工技术展开研究,基于MIDASGTSNX软件建立有限元模型,分别阐述刚性过渡、柔性过渡和刚柔结合过渡3种差异沉降控制方案,有限元模型计算结果显示,软基处理技术指标方面,刚性过渡方案和刚–柔结合过渡方案具有工期短、沉降小,地基承载力强的特点,但另一方面,柔性过渡方案存在建设工期较长、地基承载力不稳定、沉降大、隐性因素较多的显著特点;造价分析方面,按照工程造价从高到低排序为刚性过渡方案>刚-柔结合过渡方案>柔性过渡方案,所以柔性过渡在造价上优势更为显著。

基于三维线形的轻型高速公路纵断面指标研究

为了探究轻型高速公路路线纵断面设计关键参数,基于Carsim/Trucksim软件搭建了人-车-路耦合系统,根据普遍性和不利性原则,选取轿车、面包车和轻型货车作为轻型车辆的代表性车型,开展了代表性车型在直坡路段和弯坡组合路段的行驶仿真。根据轻型车辆在纵断面和弯坡组合路段运行特征,确定了轻型高速公路的控制车型以及路线纵断面的坡度、坡长参数。结果表明:轻型高速公路纵断面设计参数应以轻型货车和面包车作为控制车型;高速行驶下,车辆在弯坡组合路段的速度衰减比在单纵坡路段更为剧烈;根据速度衰减特性和允许速度降幅,轻型高速公路设计速度为100km/h时,若允许轻型货车通行,应以比功率为25W/kg的轻型货车作为控制车辆,路线纵断面最大纵坡为5%,最大坡长为750m,若不允许轻型货车通行,路线纵断面最大纵坡为6%,可不限制最大坡长;设计速度为120km/h和140km/h时,应以比功率为35W/kg的面包车作为控制车辆,路线纵断面最大纵坡分别为6%和5%,对应的最大坡长均为1200m。

高速公路路-桥过渡段桥头搭板受力研究

布设桥头搭板可有效解决路-桥过渡段差异沉降引起的桥头跳车问题。文章采用梁和地基支承刚度统一计算的有限元法确定搭板的设计参数,基于数值模拟方法研究了搭板在不同布设方案中的受力情况,确定了桥头搭板最易破坏的位置,明确了搭板的最优布设方案。结果表明:随着搭板厚度和长度的增加,搭板所受最大弯矩值增大,搭板末端越易产生集中应力,导致二次跳车问题,即搭板厚度和长度存在最优尺寸,搭板长度为10 m时,最佳厚度为0.35~0.45 m,而当搭板厚度为0.35 m时,其最佳长度为8 m;搭板与桥台铰接且深埋搭板有利于搭板的长期稳定;采用搭板可以有效避免桥头跳车问题,与常规搭板布设方案相比,深埋搭板布设方案所受的竖向压力、弯矩和挠度均有显著降低;搭板上部回填材料为水泥稳定级配碎石时,可以有效地改善搭板的承载性能。

高速公路运营风险分析及突发事件预警系统

分析了运营高速公路高风险路段的风险特征,针对风险路段常见风险场景,开发一种风险识别预警系统,可对管控路段的突发事件进行快速识别、信息上报,并通过发布预警信息辅助驾驶员感知风险及通知相关部门对现场进行安全管控。该系统实现了高速公路突发事件快速识别与现场管控,为提升高速公路风险路段运营安全提供了技术保障。

高危路段线形设计研究

随着交通网络的日益完善,因道路线形问题而导致的交通事故逐渐增加,尤其是在高危道路路段,线形设计不合理或设计指标应用不当极易引发交通事故。为探究高危路段线形设计对道路安全的影响,文章深入研究了高危路段的线形特征和线形设计要点,从改善弯道陡坡路段线形、线形视距控制设计、纵坡坡度和坡长设计三方面提出改进对策,以减少高危路段的安全隐患。

路桥工程中路基路面沉降段设计分析

为切实提升当前路桥工程整体施工质量,降低路桥工程的路基路面沉降问题的出现概率,最大限度地推动我国路桥建设领域的发展速度,本文将对路桥工程中路基路面沉降段设计进行分析与研讨。文章首先对其路基路面沉降段设计的重要性进行阐述;其次对其设计原则及设计因素进行解析;再次对其路桥工程沉降段出现沉降的原因进行简述;最后对其路基路面沉降段设计要点进行分析,以供参考与借鉴。