Dawson Water in Road Structures

Movement, Drainage & Effects
1. Auflage 2008
ISBN: 978-1-4020-8562-8
Verlag: Springer Netherland
Format: PDF
Kopierschutz: 1 - PDF Watermark

E-Book, Englisch, 438 Seiten, Web PDF

Reihe: Earth and Environmental Science

Background This book is the most obvious outcome of the “COST 351, WATMOVE” project (see www. watmove. org). For most readers these terms probably mean little so some explanation is called for. In 2001/2002 a small group led by Kent Gustafson of the Swedish Road and Traf c Institute (VTI) made a proposal to the European programme on “Co-operation in Science and Technology” (COST). They proposed that a pan-European team be set up to study the issue of “Water Movements in Road Pavements and Embankments” (acronym = WATMOVE). The COST organisation agreed the proposal and the study formally began in December 2003 with the s- port of COST. Due to ill-health, Kent was not able to lead the project and I was asked by the Management Committee to chair the project team. Scope of the Book This book is NOT about “Water and Roads”, nor on “Water on Roads”. There are other books which deal with surface water drainage in great detail and there are other source materials that deal with the impact of roads on water in the general environment. To cover every aspect of the interaction between water and highways would have required a much greater effort and a much thicker book. So this book seeks to limit itself to: (i) Water inside the road construction and the underlying subgrade soils and rocks; 1 (ii) Water from the surface down to the phreatic surface, and (iii) Water in the road and ground between the fence-lines of the highway.

Zielgruppe

Professional/practitioner

Autoren/Hrsg.

Dawson, Andrew

Inhaltsverzeichnis

Water Flow Theory for Saturated and Unsaturated Pavement Material.- Measurement Techniques for Water Flow.- Heat Transfer in Soils.- Water in the Pavement Surfacing.- Sources and Fate of Water Contaminants in Roads.- Contaminant Sampling and Analysis.- Water Influence on Bearing Capacity and Pavement Performance: Field Observations.- Water Influence on Mechanical Behaviour of Pavements: Constitutive Modelling.- Water Influence on Mechanical Behaviour of Pavements: Experimental Investigation.- Modelling Coupled Mechanics, Moisture and Heat in Pavement Structures.- Pollution Mitigation.- Control of Pavement Water and Pollution Prevention.

Leseproben

Abstract This introduction provides a brief review of the history of highway subdrainage before setting out the aims and organisation of the book of which it forms the first chapter. It gives an overview of the subjects to be covered in the following chapters, introduces the key topics including definitions of subgrade and pavement layers, their classification from a drainage point-of-view together with a brief coverage of the principle of effective stress, suction, leaching and water movement due to evaporation and frost-heave. It outlines the way in which pavements and the hydrological environment interact before introducing the reader to the varieties of climate in which highways and pavements have to operate – a task that is likely to become more onerous in the light of climate change effects.

Keywords Introduction · history · definition · drainage classification of pavements · alternative materials · drainage systems · climate

1.1 Some History

In Europe road construction may date back as far as 3,500 years ago. These early roads were probably largely for ceremonial purposes, over short distances, and may have carried little, if any, wheeled traffic. It was not until the growth of the Roman Empire that a large network of engineered pavements was first constructed (Fig. 1.1). Such was the desire to secure the Empire against enemies and to enhance trade that, at the peak time, about 0.5 km was being built daily. Although foot and hoof traffic probably predominated, those roads were certainly used for wheeled vehicles too.

The engineers responsible for these pavements understood some important truths about pavement drainage – truths which, in practice, sometimes are still not recognised today. Figure 1.2 shows a cross section of a high quality Roman road. It illustrates that its designer:

- provided cross-fall to help shed surface water to the margins rather than to soak in,

- raised the pavement well above the groundwater level of the surrounding ground so as to keep the amount of water in the embankment low and the effective stress (and, hence, soil strength) high,

- provided lateral ditches to prevent water table rise in wet periods and to convey draining water away from the construction.

Only a small proportion of pavements were built as illustrated, more generally a two layer pavement, comprising nucleus and rudus as explained in the notes to the Figure, was constructed on an embankment (agger – see Fig. 1.2). Despite the economizing on materials, the aim of keeping the construction well-drained remained unaltered.

It was not until the late 1700s and early 1800s that a similar understanding was once again developed. Figure 1.3 shows a cross-section of a main coach pavement as designed by Thomas Telford, the Scottish engineer who worked in the UK and other European countries between about 1800 and 1830. In this design an effort has been made to provide a relatively impermeable surface to prevent water infiltration and a drainable foundation, but the route to lateral drains from these is not well developed.