Abstract

During the course of the past decade a somewhat revolutionary approach to geotechnical engineering design has appeared, in the form of the design code EN-1997 Geotechnical Design, popularly known as Eurocode 7, or EC7. This article reviews the development of EC7 and the basis of the design philosophy it embraces, namely Limit State Design (LSD), before going on to show how LSD is currently implemented within EC7. Following this, the key issues of applying LSD to rock engineering design are explored, before closing with a review of how the forthcoming revision of EC7 - planned for 2020 - will display improved applicability to rock engineering design. Throughout these Sections, areas where customary rock engineering design practice will need to evolve in order to be compliant with the principles of LSD are highlighted.

1.
Introduction

In a number of countries around the world, and particularly those countries forming the European Union, a new design code for geotechnical engineering design has recently been adopted. This code is properly known as EN-1997 Geotechnical Design (CEN, 2004), but is often informally referred to as Eurocode 7 or EC7. It implements Limit State Design, often abbreviated to LSD.

The application of EC7 to geotechnical engineering design in general, and rock engineering design in particular, is proving to be somewhat problematic. There seem to be many reasons for this but, as this article attempts to show, in the context of rock engineering it seems that the principal ones are (i) a lack of understanding of LSD, and (ii) a divergence between customary rock engineering design practice and LSD.

The Sections that follow begin with reviews of the development of EC7 and the basis of LSD, before going on to showing how LSD is currently implemented within EC7. Following this, the key issues of applying LSD to rock engineering design by calculation are explored, before closing with a review of how the forthcoming revision of EC7 will display improved applicability to rock engineering design. Throughout these Sections, areas where customary rock engineering design practice will need to evolve in order to be compliant with the principles of LSD are highlighted.

2.
Historical development of Eurocode 7

Eurocode 7 is one of a suite of nine highly integrated codes that together form the Structural Eurocodes (Fig. 1). As Table 1 shows, genesis of the Structural Eurocodes is inextricably bound up with the political development of the EU, can arguably be traced to the Treaty of Rome, but tangibly can be taken as 1975. From 1975 to 2018 means that EC7 is thus 43 years old: it is not new, despite many in the rock mechanics and rock engineering community learning of its existence comparatively recently.

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