26
Geotechnical News • June 2019
THE GROUT LINE
Introduction
53
rd
episode and for this issue an
article written by me about jet grout-
ing with a challenging project in
cobbly/bouldery soils. I hope you will
enjoy reading.
News from the grouting industry. I just
read an excellent document that I think
should be on every grouting practitio-
ner’s bookshelf. The document was
prepared by a UK association based in
London, CIRIA (Construction Industry
Research and Information Associa-
tion): Grouting for reservoir dams - a
guide to good practice. The report is
called C774 and can be ordered on
line
To Shadow or not to Shadow
Is it a real problem in Jet Grouting?
A case history that shows that it is not
Introduction
Shadowing is a word used very often
in jet grouting. The question is: ”how
can shadowing be created (or occur)
in this specialized area of soil treat-
ment?”
The Cambridge dictionary defines
a shadow as: “an area of darkness
caused by light being blocked by
something”. Translated to the lan-
guage of jet grouting, shadowing can
happen when the jet/s of the disaggre-
gated fluid/s (water or grout mix +/-
air) are blocked by something such as
cobbles, boulders or the presence of
other objects in the soil.
It is clear that the designer and/or
specialty contractor should know
if one of these conditions exists,
especially man-made obstructions,
and consequently be able to take
the appropriate action. If there are
known obstructions it is quite easy
to adapt the geometry and arrive at
the scope of work for the jet grout-
ing. A very interesting case history is
a project of jet grouting done at the
Seawall in Seattle where jet grout-
ing was “sudoku-ed” between old
timber piles. But what should be done
in case of erratic and unpredictable
cobbles/boulders? Discard the tech-
nology? Or?
The case history described in this
article will provide some possible
Figure 1: The site.
