Geoscientist Online

WORKING PARTY

The Working Party first met in late 2003, under the Chairmanship of John Charman, who led a multidisciplinary team of desert specialists drawn variously from engineering and geoscience backgrounds and representing commercial, consultancy and academic activities (see online version). An invaluable aspect of the report’s compilation was a thorough process of regular peer review as the chapters took shape. The Working Party had regular face-to-face meetings for five years, where issues were thrashed out and chapter drafts openly discussed and improved. Therefore the whole Working Party is jointly responsible for every chapter in this handbook.

Along the way, the Working Party received help from many acknowledged correspondents and benefited from a dedicated session at the International Association for Engineering Geology Congress in Nottingham in 2006. Once the report/book had been compiled and edited, Professor Sir Ronald Cooke, a renowned geomorphological pioneer in desert regions honoured the Working Party with a Foreword, concluding: "This comprehensive, state-of-the-science review successfully brings together the experience gained over recent years of many engineering geomorphologists and geologists into one volume. It integrates knowledge of the landforms and the processes that have worked on them over time with studies of the nature and behaviour of materials, appropriate techniques of analysis, and guidelines for the choice of engineering designs, construction methods and materials. It should be an essential guide to all who seek to develop land in hot deserts."

When we reached the end of our main ‘face-to-face’ compilation period in 2008, prior to the lengthy process of detailed editing, the Working Party unanimously agreed to dedicate the volume to Peter Fookes. As well as being timely recognition of his tireless support for the Engineering Group and many of its members individually, this was also appropriate because of his unrivalled contribution to the partnership between geologists and engineers in understanding, confronting and ultimately solving the many challenges facing successful construction in hot desert regions.

The handbook can be used as a reference work, aided by a detailed index, an extensive specialised glossary distilled from the various chapters, and extensive reference lists supporting each chapter. However, it can equally be used as a textbook, for work, education or – we hope - just for pleasure! To these ends, following a scene-setting introductory first chapter, the report is structured into three main themes: Geological and geomorphological background (Chapters 2 to 4), Investigation and testing (5 to 7) and Engineering behaviour (8 to 10): (See online for more detail). All chapters are copiously illustrated, including many images and diagrams in colour, courtesy of generous sponsorship from Arup, Fugro and Fugro-Suhaimi.

Professor David Nash leads off in Chapter 2 with a geographical overview, including the distribution of hot deserts, causes of aridity, controls over diversity, and discussion of past and future changes. This review is complemented by an extensive account of desert processes and the landforms they create in Chapter 3, from Professor Jim Griffiths and his team. Processes are presented in four categories: weathering and duricrust formation; wind, sand and dust; fluvial; and subsurface water, salts and aggressive ground.

EARTH SYSTEMS

An important theme of the report was to review, update and apply the existing desert ground models, including those pioneered by Fookes & Knill in 1969 and still widely used. In Chapter 4, after a review of desert models and hazards, an 'Earth Systems' geomodel is proposed, based upon desk study and mapping data, which can be used to devise site-specific models, for further refinement by actual ground investigation. This new scheme is supported by nearly 40 superb colour images. This section of the report could well be used as a field guide to the identification of desert landforms and features.

Three chapters on investigation and testing seek to avoid being a mini ‘site and ground investigation’ textbook, and aim instead to provide particular information and guidance that will be relevant to work in hot desert regions. In Chapter 5, Dr Martin Stokes and his team explain the distinct characteristics and classification of hot desert soils and rocks, including their relationship to the desert model, and propose a scheme based on an extension to the respected Atkinson recommendations.

In Chapter 6, David Shilston explains the adaptation of desk study and phased field evaluation techniques to hot desert conditions, especially relating such investigations to the conceptual ground model. A section on remote sensing is provided by specialist corresponding co-author, Dr Richard Teeuw. All this is helpfully supported by examples of some new techniques and short case histories. Finally, Roger Epps in Chapter 7 describes the application of detailed ground investigation and testing methods to hot desert locations and materials, again including actual examples and case studies, plus a very useful appendix, giving guidance on the ways in which standard tests and/or their interpretations can be affected by hot desert conditions.

CONSTRUCTION MATERIALS

The final three chapters give guidance on the application of the earlier-defined characteristics and models to actual engineering behaviour and applications. Professor Matthew Coop, in Chapter 8, explains the ways in which desert soils can respond to construction activity, including mechanical properties, moisture and saturation issues, variously collapsible, expansive or salt-bearing soils and cemented soils. In Chapter 9, Dr Alan Poole leads on a wide-ranging and well illustrated assessment of construction materials in deserts, including rock, stone and armourstone, aggregates, road-making materials, concrete and mortar, traditional materials including bricks, recycled materials and water. Details are often provided separately in text-boxes, such as an account of alkali-aggregate reaction.

Caption : Typical map cracking of concrete caused by alkali-silica reaction.

Philip Dauncey completes the final part of this theme (Chapter 10), by considering engineering design and construction in hot deserts. Major types of construction are addressed in turn, including earthworks, foundations, roads and pipelines, coastal development (dredging, reclamation & shore protection), concrete structures and traditional construction, such as adobe. This chapter also addresses some of the practical effects of - and responses to - key desert hazards to construction, including flooding and erosion, groundwater changes as a consequence of development, and wind-blown sand.

We believe that this long-awaited handbook has achieved its objectives and should act as a helpful guide and authoritative reference. At some stage, as with previous reports of this type, it is probable that a new Working Party will be formed to revise, amend and improve sections in which understanding has advanced and, above all, add new experience and newly developed techniques. The Engineering Group therefore welcomes any feedback!