Preface

Granular materials are present in numerous sectors of economic activity outside civil engineering, from agriculture and agro-industry to pharmaceutical and chemical industries, mining industry, etc. It is estimated that more than two-thirds of raw materials used by world industries are in the form of granular materials, involving gigantic quantities, about 10 billion tons each year, of which processing and transport represent about 10% of energy consumption worldwide [DUR 96]. However, most often, the methods for their process remain rather traditional and lack optimization.

Regarding geomaterials, sand for the construction industry is the second most consumed natural resource after water [LEH 018], and its extraction represents serious environmental issues in certain areas, (including the disappearance of beaches and retreat of shoreline).

Construction of large civil engineering infrastructures commonly involves large volumes of earthfills and rockfills, constituted by sand, gravel, and rock blocks, sometimes up to tens of millions of cubic meters or even more, as in highways or railway platforms, marine infrastructures or large rockfill dams (see Figure 1). Examples of these include the Grand-Maison Dam in France (height 160 m, volume 14 hm3) with a central compacted clay core, or the Campos Novos Dam in Brazil (202 m, 13 hm3) with an impervious concrete slab on the upstream face, which will be discussed in Chapter 10.

For this last type of dams, which has become dominant in dam construction today, a major part of the design methods is based on the empirical extrapolation of the standard ones used (in the past) for lower dams. This empirical approach, based on experience, has led to serious technical accidents during commissioning on very high dams in the mid-2000s. As a consequence, concern in the profession has arisen, prompting a return to more rational approaches in design, and particularly Granular Geomaterials Dissipative Mechanics engineering approaches, through structural analysis and relevant material testing as should be the case for any large civil engineering structure. This highlights the need to improve our knowledge of the behavior of the granular geomaterials constituting these infrastructures, as well as of the behavior of these large structures. A way for such improvement may be sought in the integration of physical local phenomena within the materials, up to the scale of the engineering structures.

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Figure 1. Large earth and rockfill infrastructures in civil engineering. (a) High-speed railway infrastructures. (b) Marine works. (c) Rockfill dams (Grand-Maison Dam – photo EDF). For a color version of the figure, please see www.iste.co.uk/frossard/geomaterials.zip

This book, resulting from a long-term work into the physics of granular materials as well as engineering of large civil works, is an attempt to relevantly move forward proposing a new vision of mechanical behavior of these granular geomaterials, through an original dissipative approach.

After an introductory section on background and key assumptions, the book begins on the main theoretical features of dissipative structures induced by elementary contact friction associated with specific statistical mechanics properties within granular materials in slow motion, and their multi-scale expression into key tensor relations, Chapters 1 and 2.

These dissipation relations and related features constitute the backbone of practical applications developed further in this book, starting in Chapter 3 focusing on strain localization and shear band detailed features, leading to the process of failure lines generation.

Then, Chapters 4–8 develop practical applications of the main macroscopic energy-dissipation equation and related features to a large set of key properties of great relevance in geotechnical and civil engineering, mainly:

Chapter 6 is focused on a wide set of experimental data collected worldwide, covering most of the experimental apparatuses, which thoroughly validate the dissipative approach of the mechanical behavior.

Although a major part of the book is focused on features induced by contact friction, the last part, Chapters 9 and 10, presents the key results on practical features resulting from particle breakage, the other main dissipative process after contact friction. These results include explicit incidences of size effects in shear strength, slope stability and safety factors, deformations and settlements in rockfill embankment dams.

Etienne FROSSARD

August 2018