Analysis of Roadbed Pavement Designs for Highway Reconstruction and Upgrading

This paper focuses on the route and roadbed pavement design in highway reconstruction and upgrading projects.It discusses the importance of project design for highway reconstruction and upgrading,highlighting key aspects of route design and roadbed pavement design.The analysis reveals that the main design considerations in these projects include controlling factors of route reconstruction,expansion,and upgrading,as well as route plan design and longitudinal section design combined with roadbed pavement.In roadbed pavement design,it is crucial for designers to thoroughly collect existing data and make reasonable use of the current roadbed and pavement to develop a comprehensive design scheme.This analysis aims to provide a reference for the reasonable design of such projects.

Mechanistic-empirical pavement design guide(MEPDG):a bird's-eye view

Past editions of the American Association of State Highway and Transportation Officials （AASHTO） Guide for Design of Pavement Structures have served well for several decades; nevertheless, many serious limitations exist for their continued use as the nation＇s primary pavement design procedures. Researchers are now incorporating the latest advances in pavement design into the new Mechanistic-Empirical Pavement Design Guide （MEPDG）, developed under the National Cooperative Highway Research Program （NCHRP） 1-37A project and adopted and published by AASHTO. The MEPDG procedure offers several dramatic improvements over the current pavement design guide and presents a new paradigm in the way pavement design is performed. However, MEPDG is substantially more complex than the AASHTO Design Guide by considering the input parameters that influence pavement performance, including traffic, climate, pavement structure and material properties, and applying the principles of engineering mechanics to predict critical pavement responses. It requires significantly more input from the designer. Some of the required data are either not tracked previously or are stored in locations not familiar to designers, and many data sets need to be preprocessed for use in the MEPDG. As a result, tremendous research work has been conducted and still more challenges need to be tackled both in federal and state levels for the full implementation of MEPDG. This paper, for the first time, provides a comprehensive bird＇s eye view for the MEPDG procedure, including the evolvement of the design methodology, an overview of the design philosophy and its components, the research conducted during the development, improvement, and implementation phases, and the challenges remained and future developments directions. It is anticipated that the efforts in this paper aid in enhancing the mechanistic-empirical based pavement design for future continuous improvement to keep up with changes in trucking, materials, construction, design concepts, computers, and so on.

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.

Preliminary <i>k</i>-Values of Unbound Natural Quartzitic Gravels for Mechanistic-Empirical Pavement Design

The generalized constitutive model relating the resilient modulus (MR) of flexible pavement layer materials to stress state, adopted by the Mechanistic-Empirical Pavement Design Guide (MEPDG), contains a set of constants known as k-values (k1, k2, and k3) which are associated with the physical state of the layer materials. In Ghana, natural gravels constitute the predominant and sometimes the sole layer materials for most flexible pavements yet representative k-values of gravel materials, have not been determined to permit full application and implementation of the mechanistic-empirical design concept to pavements involving such materials. In this study, k-values characterising typical natural quartzitic gravels used for road construction in the country were derived by regression techniques from MR values determined using laboratory repeated load triaxial test. Using multiple linear regression technique, correlation relationships were then developed between the k-values and the physical properties of the gravels, namely, percentages of materials passing the 9.5 mm (P9.5) and 2.0 mm (P2.0) sieves, liquid limit (LL), maximum dry density (ρdmax), and optimum moisture content (wopt). The regression analysis returned k1 values which ranged between 441 and 958 with a mean of 516;k2 which varied between 0.0636 and 0.2168 with a mean value of 0.1216;and, k3 values which ranged between 0.1257 and 3.1590 with a mean value of 1.723. Contrary to what is mostly reported in literature, the analysis returned positive k3 values for all but one gravel material, suggesting stress hardening under octahedral shear stress for those materials. While an expanded sample base is required to fully characterize the whole gamut of natural gravels used in pavement construction in the country, this study on limited quartzitic gravel samples has given a good indication of strong linear correlations between the k-values and the index properties of the gravels, to permit estimates of the constants for such gravels be made where capability and opportunity for conducting resilient modulus tests do not exist.However, further work is recommended to fully characterise the exact nature of k3 values for quartzitic gravels in the country.

Hierarchical methodology to evaluate the quality of disparate axle load data sources for pavement design

Axle load data are an essential input for pavement design,yet for most North American agencies,there is uncertainty about the quality of axle load data obtained from weigh-inmotion(WIM)systems,the applicability of these data for pavement design,and potential opportunities to integrate axle load data from disparate sources.This article presents a novel and practical methodology to evaluate the quality of axle load data from WIM systems and roadside weigh scales through a series of hierarchical analyses designed to test data validity.When applied using data from Manitoba,Canada,the methodology quantified the uncertainty of axle loads measured at the weigh scales and piezo-quartz WIM,concluding that both could be used for pavement design applications.Data collected at piezo-polymer WIM sites exhibited poorer data validity;however,application of site-specific temperature correction factors significantly improved data validity at these sites.The article describes how other data quality dimensions,including spatial coverage,temporal coverage,and long-term data availability,could be considered when determining the suitability of disparate axle load data sources for pavement design.Application of the methodology enables a pragmatic evaluation of the quality and limitations of commonlyavailable axle load data,revealing uncertainties and data needs relevant for pavement design practice.

Estimation of the Equivalent Design Temperature of a Pavement in Burkina Faso

The bituminous pavements of the city of Ouagadougou(Burkina Faso)are made using old design methods which take into account the climate from the notion of equivalent temperature.Thus an equivalent temperature of 30°C is often used for the design of bituminous pavements.The observation that has been made is that this temperature does not currently make it possible to reduce the problems of early degradation of the pavements linked to meteorological fluctuations.The objective of this article is to propose a numerical approach for determining the equivalent temperature from temperature measurements taken at the surface of the pavement.This approach consists in jointly using the Alizé-Lcpc sizing software and the Comsol Multiphysics software using the finite element method.For a four-layer bituminous pavement,located at 12.38°North and 1.48°West,in Ouagadougou,consisting of a surface course of bituminous concrete of 8 cm and a base course of gravel bitumen of 16 cm,an equivalent temperature of 35°C was obtained.

Multi-gene genetic programming extension of AASHTO M-E for design oflow-volume concrete pavements

The American Association of State Highway and Transportation Officials Mechanistic-Empirical Pavement DesignGuide (AASHTO M-E) offers an opportunity to design more economical and sustainable high-volume rigid pavementscompared to conventional design guidelines. It is achieved through optimizing pavement structural andthickness design under specified climate and traffic conditions using advanced M-E principles, thereby minimizingeconomic costs and environmental impact. However, the implementation of AASHTO M-E design for low-volumeconcrete pavements using AASHTOWare Pavement ME Design (Pavement ME) software is often overly conservative.This is because Pavement ME specifies the minimum design thickness of concrete slab as 152.4 mm (6 in.). Thispaper introduces a novel extension of the AASHTO M-E framework for the design of low-volume joint plain concretepavements (JPCPs) without modification of Pavement ME. It utilizes multi-gene genetic programming (MGGP)-based computational models to obtain rapid solutions for JPCP damage accumulation and long-term performanceanalyses. The developed MGGP models simulate the fatigue damage and differential energy accumulations. Thispermits the prediction of transverse cracking and joint faulting for a wide range of design input parameters and axlespectrum. The developed MGGP-based models match Pavement ME-predicted cracking and faulting for rigidpavements with conventional concrete slab thicknesses and enable rational extrapolation of performance predictionfor thinner JPCPs. This paper demonstrates how the developed computational model enables sustainable lowvolumepavement design using optimized ME solutions for Pittsburgh, PA, conditions.

A systematic review of steel bridge deck pavement in China

As an important part of steel bridge deck,the engineering quality and service condition of steel bridge deck pavement(SBDP)directly affects the capacity and operational efficiency of the bridge.This paper reviews the history of the development of SBDP in China over the past 20 years from the exploration stage,rapid development stage and prosperity stage.The development and application of SBDP at different stages are discussed in terms of materials,structure,design,performance evaluation,maintenance and rehabilitation,respectively.The advantages and disadvantages of different pavement materials and structures,and the application of different research methods are summarized.The review shows that the improvement of pavement materials and structures and the development of new materials should be further studied on the multi-scale to enhance the durability of pavement materials,so as to extend the service life of pavements.The design method of SBDP related to the synergistic effect of vehicle,pavement and bridge should be established,and the design concept and method standard of rigid base pavement structure should be improved and formulate a complete design standard.In addition,multi-disease intelligent identification system and equipment should be studied to track the entire course of disease development in real time.And it is necessary to develop appropriate algorithms to select and classify the complex data of disease and maintenance history.

A review on the best practices in concrete pavement design and materials in wet-freeze climates similar to Michigan

The research presented in this paper aims to identify best practices of design and materials for concrete pavements in wet-freeze climates similar to the Michigan State. For the purposes of this paper, a best practice is a procedure that has been shown by field-validated research or experience to produce improved results and that is established or proposed as a standard suitable for widespread implementation. The local wet-freeze climate makes the requirements for Michigan's pavement system different from many other regions. Wetfreeze climates can result in various concrete pavement distress mechanisms such as thermally-induced cracking, freeze-thaw deterioration, accelerated cracking due to loss of support, frost heave, and material degradation. Therefore, appropriate procedures for design and material selection need to be selected to withstand high precipitation and freezing winter temperatures. Failure to take into account the climatic conditions may lead to inadequate or reduced pavement performance. However, utilizing appropriate techniques and materials could potentially improve the quality and increase the service life of the concrete pavement. Three design methods and five materials have been identified, and examples of their successful performance in wet-freeze climates are provided. In addition, the reasons that give them the superior performance in wet-freeze climates are discussed in detail.

OPTIMUM DESIGN OF FLEXIBLE PAVEMENT STRUCTURE BY FLEXIPLEX TOLERANCE METHOD

The optimum design for flexible pavement structure is studied by using themethod of mathematical programming.The mathematical model is founded on the basisof“Design Code of Highway Flexible Pavement”issued by the Ministry of Communica-tions of China.The objective function is the cost of pavement structure.The optimal solu-tions of the mathematical model were searched successfully by flexiplex tolerance method.The relevant program has been developed on DPS-8 and IBM-PC computers.And thecalculated results show good convergence and accuracy for engineering applications.

Structural Design of Asphalt Pavement for Low Cost Rural Roads

On the basis of the equivalent axle load action frequency, the traffic classifications of rural roads as well as their corresponding types are classified. The asphalt pavement structure, road surface types and thickness of the rural roads are suggested for the various action frequency of the equivalent axle load. Furthermore, the roadbase thickness graphs are provided according to different equivalent axle load action frequency with different roadbed modulus and road surface modulus taken into account.

AC-13C沥青混合料配比设计及性能试验研究

文中基于马歇尔试验的AC-13C设计方法和基于Superpave系统的Sup-13(即Superpave 13 mm)设计方法,对两种不同的沥青混合料配合比设计进行研究,对比各自的特点、优势以及适用性。研究表明,对于两种设计方法所得到的油石比设计指标来说,Superpave法的空隙率和毛体积相对密度表现较好,马歇尔法的矿料间隙率和沥青饱和度表现较好;对于沥青混合料的路用性能来说,Superpave法的高温和水稳定性更好,马歇尔法的低温性能更好。

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。

用于隧道路面检测的照明系统设计

为保证隧道路面检测系统的高检测精度,本研究设计了一款适用于自动路面检测系统的双光源照明系统来实现被测路面的均匀照明。该系统通过9×7矩形LED阵列配以矩形复合抛物面聚光器对5 m×2.2 m的路面进行双光源倾斜照明,两光源之间的距离为1.3 m,向车辆后方及车辆外侧分别倾斜13°和26°。经过不断优化,在1.8 m的照明高度下,该系统的光照均匀度达到84.24%,被测路面的平均光照度达到21 135 lx,光能利用率为58.5%。相较于目前隧道路面检测的照明系统,本文设计的系统稳定性较好、照度较高、照明范围较大,公差要求原则上满足现代加工水平,并且成本较低、寿命较长、结构紧凑、容易装调,可满足隧道路面检测的照明需求。

回弹模量路基参数对公路路面设计的影响研究

为了更科学、精准地完成公路路面设计工作,定量分析回弹模量路基参数与公路路面设计的关系,更精准地测算和衡量路基参数对公路路面设计的影响,全面提升公路设计水准,本文首先从回弹模量概念出发,其次提出了基于回弹模量的路基设计PFWD测试法及参数评估标准,最后采用实际工程的模拟测试实验结果衡量了回弹模量参数变化与公路路面设计之间的关系,从而分析了不同参数下路面设计各层级稳定性的变化。

市政道路改扩建工程中路基路面设计优化策略分析

研究了市政道路改扩建工程中路基路面设计优化策略,在明确改扩建道路工程病害及主要原因的基础上,从总体方案设计、软基处理设计、路基拼接设计、路面结构设计、道路排水设计等方面出发,分析了路基路面优化设计的有效措施,有利于改善新旧道路的结合效果,解决改扩建工程设计的重难点问题。

低噪声柔性加固基层沥青路面结构设计研究

为减少沥青路面的不平整度,提升路面结构承载性能与行车舒适性,开展低噪声柔性加固基层沥青路面结构设计研究。首先,根据设计目标和工程需求,确定合理的级配范围;其次,基于路面结构层厚度力学分析结果,设计路面结构层厚度;最后,利用低噪声柔性加固基层技术设计沥青路面的各个层次结构。应用分析结果表明,应用文章提出的设计方法后,路面平整度均方差始终较低,可以有效改善沥青路面的平整度,保证路面性能与行车舒适性。

Theoretical Development and Engineering Practice of Pavements in China

This paper presents a comprehensive review of historical theory development and current construction practice of pavement engineering in China. Mechanical models, design guides, construction techniques, evaluation methods and maintenance standards are elaborated for Portland cement concrete （PCC） pavements methodology among pavements of rural highways, urban roads and asphalt concrete （AC） pavements. Differences in design and airport fields are discussed based on service requirements. Lessons and experiences based on the past 20 years＇ construction practice and pavement performance are summarized. Current research areas in pavement engineering associated with unconventional geological and/or landscaping in China＇s highway construction and national strategic plan for pavement engineering are also covered.

长大纵坡沥青路面车辙发展规律与轴载换算修正系数研究

现有设计规范未对长大纵坡路面做出特殊设计规定,直接套用设计规范忽略了其受力特点,不能较好地保证路面使用性能及寿命。为实现特殊路段路面结构差异化设计,该文基于实测沥青混合料动态模量、全年交通量及温度数据,利用自主开发的温度-轴载分析软件,将真实交通量转换为标准轴载。采用Abaqus软件,建立实测轴载与温度耦合作用下的车辙模型,分析长大纵坡对车辙发展规律的影响。研究表明:坡度增大导致速度降低,容易引发长大纵坡路段沥青路面车辙病害的发生。基于车辙等效原理,提出不同坡度及坡长下的轴载换算修正系数,为长大纵坡路段沥青路面的差异化设计提供理论依据。