Grouting
Grouting is just one of the major techniques that Menard Bachy is able to offer in the complex field of ground improvement. The main categories of injection grouting available are:
Permeation Grouting
The principal purposes of permeation grouting are for waterproofing and strengthening the soil or rock. Permeation Grouting relies on impregnating the voids within a soil or rock mass and thereby displacing water and air from the voids and replacing it with grout, without displacing the soil particles or widening the existing fissures in the rock. Grouts are required to have high levels of fluidity and stability and in the case of high penetration particular grouts, contain extremely fine particles.
Permeation Grouting is strictly a low pressure operation aimed at impregnation of the soil or rock. Elevated pressures that exceed the lowest principal stress at the point of injection in the soil cause 'Claquage', where a fissure in the soil is opened in a plane perpendicular to the minimum principal stress defeating the objective of impregnation. In rock, elevated pressure in grout will encourage destabilisation and segregation, resulting in decreased effectiveness of the grouting process. Pressures must be carefully contained to avoid this phenomenon.
Compensation Grouting
Compansation grouting is an active technique to mitigate settlement arising from other engineering works (such as tunnel excavation) in order to provide protection to existing structures. Compensation grouting can take the form of permeation, compaction, or hydro fracture grouting depending on the local conditions of the given project. This is done concurrently with the progress of the tunnel and grouting parameters are continually adjusted with reference to measured movements of the ground and surface structures, to keep settlement and deformations within specified limits.
Compaction Grouting
The injection of stiff mortar or paste instead of fluid grout to displace laterally and compact the soil in situ, thus improving its engineering characteristics.
Hydro Fracture Grouting
Involves the deliberate fracturing of the soil or rock by grout under pressure. The resulting compaction and stiffening of the rock or soil mass can, in appropriate conditions, provide ground improvement where permeation grouting is not practicable.
Rock Grouting
Grout infilling of discontinuities, fissures, fractures or joints in mass rock with the intention of reducing permeability and increasing the competence of the mass rock. This technique is frequently employed for dam construction and tunnelling.
Cavity Grouting
Cavity Grouting is most commonly, though not exclusively, used for backfilling abandoned mine workings to avoid the development of settlement or worse, sink holes, at the ground surface, attributable to collapse of large underground voids. The process involves drilling into the cavity then pumping grout to either fill the void in part or in full as the design demands.
The injection methods that can be employed for the above techniques range from packer injection via a Tube a Manchette (TaM), packer injection direct into rock, descending / assecending stage grouting, grout injection direct via drilling tools (end of casing grouting), lancing or via surface strand pipe.
