Underground Investigation
and Risk Management
Managing geotechnical risk without being afraid
By Masoud Manzari, P.Eng. and Mark Tigchelaar, P. Eng., GeoSolv Design/Build
In the last article, we covered the relationship between
projects and risk.
In this is the third and final installment, we will discuss
the right way to manage geotechnical risk as it pertains to
high-risk projects.
The first item that should be discussed is the geotechnical
investigation itself – which should be done first (or at least
early) on any planned construction project.
Standard Penetration Test (SPT) investigation methods
are a “tried-and-true,” 100-year-old technology which
have been, and should be, the backbone of most geotechnical
investigations. Unfortunately, more often than not, SPT
becomes the sole method of investigating for all soil conditions,
regardless of the size or complexity of the project. It’s
TECHNICAL
PPAARRTT 33
true that SPT is indeed an excellent way to collect some soil
samples, check lithology and provide qualitative strength
data. However, SPT does come with some rather significant
limitations with regard to specific soil types, and is often
fraught with potential machine and human error including
drilling method errors, hammer efficiency errors, soil sampling
disturbance errors, drill type errors, mathematics or
interpretation errors, to list a few.
There are numerous investigation methods that need to
be applied correctly to ensure a project’s investigative stage
is conducted in the most thorough and risk-adverse way possible
based on the unique geotechnical conditions of the area
(e.g. soft soil versus hard soil) and complexity of the project
(e.g. low-rise building versus bridge). There are methods such
CONTINUED ON PAGE 69
GEFUFNA/123RF
Unfortunately, more often
than not, SPT becomes the sole
method of investigating for all
soil conditions, regardless of the
size or complexity of the project.
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