Grouting involves the injection of a pumpable material (slurry or grout), to fill the voids between soil grains in order to strengthen the soil mass or to reduce its permeability. If the grout material can fill the voids between the soil particles without appreciable movement of the surrounding material the process is referred to as permeation grouting.
This technique is generally used to reduce the permeability and/or to strengthen and stiffen the ground. It can be used to control groundwater during excavations and is therefore particularly suited for the construction of basements. It is also useful for treating soils prior to tunnelling, settlement control and temporary strengthening of soils below structures.
HOW IT WORKS
Permeation grouting works through the installation of Tube a Manchette (TaM) pipes into the area requiring treatment. Built into the TaM are rubber sleeves, which cover the grouting holes and adjacent to these are packers. Grout is then pumped into the TaM and forced through the holes and out past the rubber sleeve into the grouting zone.
Grout is injected on a primary and secondary basis. The secondary injections involve using a finer grout mix and the scope is determined from the results of the primary grouting. The injections are computer controlled ensuring not only accuracy but to aid efficiency and avoid waste.
The system drives the vast amount of data required for each grouting operation, at every level of production: the setting-up stage (borehole geometry and the calculations of the volumes of grout needed) the acquisition and injection settings, controlling the grouting plant (monitoring the pumps, acquiring flowrate and injection-pressure data), and tracking quality and production.
Capability: Depending upon ground conditions, on average, borehole depths are approximately 20m, but this varies depending on the scope of works. Borehole diameters range between 90mm and 150mm. Pressures to suit the ground conditions and requirements of specification.
Advantages:It forms a strong bond that is both waterproof and permanent. Clean and non-intrusive. Improves the bearing capacity of soil and can help with settlement control.