Environmental Engineering Reference
In-Depth Information
Managing risk and achieving reliable
geotechnical designs using eurocode 7
Trevor L.L. Orr
10.1 IntroDuCtIon
Eurocode 7, published by CEN, the European Committee for Standardization, as EN 1997
with two parts, Part 1: General Rules (CEN, 2004), hereafter referred to as Eurocode 7,
and Part 2: Ground Investigation and Testing (CEN, 2007), is the new European stan-
dard for geotechnical design. Since 2010, Eurocode 7 has superseded the existing national
standards for geotechnical design in all the CEN member countries. Eurocode 7 aims to
achieve geotechnical designs with appropriate degrees of reliability using the limit state
design method as set out in the head Eurocode, EN 1990 (CEN, 2002), which gener-
ally involves calculations with partial factors applied to characteristic parameter values.
Until the introduction of Eurocode 7, there had been little experience in Europe in the
use of the limit state design method for geotechnical design. Hence, its introduction has
caused considerable debate and some resistance, often due to misunderstandings about
how Eurocode 7 has adapted the limit state method in EN 1990 for geotechnical design.
This chapter reviews how the important aspects of risk and reliability in geotechnical
design are addressed in Eurocode 7. In particular, it explains how geotechnical designs
with appropriate degrees of reliability are achieved by using calculations with partial fac-
tors applied to appropriately selected characteristic parameter values and quality manage-
ment measures related to the different stages of a geotechnical design project which are
ground investigation, design calculations, construction, and monitoring and maintenance
after construction.
10.2 geoteChnICal CoMPleXItY anD rISk
10.2.1 Factors affecting complexity
All civil engineering involves risk, but geotechnical designs generally involve more risk than
other areas of civil engineering due to the complexity of the ground and uncertainties about
its properties. Hence, Eurocode 7 provides a methodology for managing risk in geotechni-
cal design. As the first stage in this methodology, Eurocode 7 states in §2.1(8)P that the
complexity of the geotechnical design shall be identified, together with the associated risks,
in order to establish the minimum requirements for the extent and content of geotechnical
investigations, calculations, and construction control checks, and the expertise required of
those involved in the different aspects. Note that the symbol § indicates a clause, that is, a
paragraph in the standard and the letter P indicates that the clause is a Principle and hence
a code requirement.
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