Managing risk and achieving reliable geotechnical designs using Eurocode 7 - Risk and Reliability in Geotechnical Engineering - page 389

Table 10.1 Geotechnical Categories related to geotechnical complexity and risk levels
Factors to be
considered affecting
design complexity

Geotechnical Categories

GC1 GC2 GC3

Hazards Low Moderate High

No difficult ground
conditions. Ground
conditions and
properties can be
determined from
routine investigations
and tests

Unusual or exceptionally
difficult ground
conditions

Ground conditions Known from comparable

local experience to be
sufficiently
straightforward. Not
involving soft, loose or
collapsible soil, or loose
ill

Groundwater
situation

No excavation below the
water table, except
where comparable local
experience indicates this
will be straightforward

No risk of damage,
without prior warning,
to structures due to
groundwater lowering
or drainage. No
exceptional water
tightness requirements

High groundwater
pressures and
exceptional
groundwater conditions,
for example, multi-
layered strata with
variability permeability

Regional seismicity Areas with no or very

low earthquake hazard

Moderate earthquake
hazard where seismic
design code (Eurocode
8) may be used

Highly seismic areas and
areas of high earthquake
hazard

Influence of the
environment

Negligible risk of
problems due to surface
water, subsidence,
hazardous chemicals, etc.

Environmental factors
covered by routine
design methods. No
exceptional loading
conditions

Complex or difficult
environmental factors
requiring special design
methods

Vulnerability

Low Moderate High

Nature and size of
the structure and its
elements

Small and relatively simple
structures or
construction. Insensitive
structures in seismic
areas

Conventional types of
structures with no
exceptional risks

Very large or unusual
structures, structures
involving abnormal risks,
and unusual or
exceptionally difficult
loading conditions

Surroundings Negligible risk of damage

to or from neighboring
structures or services
and negligible risk for
loss of human life

No exceptional risk of
damage to neighboring
structures or services
due, for example, to
excavation or piling
and no exceptional
risk for loss of
human life

High risk of damage to
neighboring structures
or services and high risk
for loss of human life

Risk Negligible Not exceptional High

geotechnical investigations and tests, the design procedures and construction control
checks, and the expertise of the designer. These are related to the Geotechnical Category,
as indicated in Table 10.2 , also adapted from Orr and Farrell (1999). The Geotechnical
Categories provide a framework for assessing the suitability of a site with respect to
the proposed construction and the level of acceptable risks since §2.8(3) states that the
Geotechnical Design Report, which is described in Section 10.3.2, should normally
include a statement on this.