The injection
of a suitable fluid grout, designed to permeate the 'problem' ground to increase
load carrying capacity or reduce or stop water flow.
The grout can consist of
various materials from the more usual cement : sand : pfa grouts to those incorporating
bentonite, microfine cements and those wholly consisting of proprietary chemical
constituents as well as sodium silicates, resins and polyurethanes.
Injection can be undertaken
to a variety of patterns and an array of depths dependent on the problem to be
overcome. The most common means of injection are 'through the lance' and from
'tube-a-manchette' The former involves drilling a casing to the appropriate depth
and grouting through the casing which is retracted as a volume or pressure is
achieved.
'Tube-a-manchette' are sleeved
ducts installed in a predrilled hole with grouting taking place through discrete
ports located at set intervals allowing the phased permeation treatment of the
particular ground at the horizon the problem has occured.
