The purpose of injections is to fill voids, improve the mechanical strength and/or decrease the permeability of the soil by injecting special, pumpable products that solidify in the soil and/or fill cavities. The injection soil improvement technique occurs either by gravity, or under pressure, or repetitively (multi step process) and most often occurs by performing boreholes in the soil to be treated, according to a pre-established grid.

Construction sequence

Most often, the injection is done in successive phases:

  • Micro perforation type of drilling technique and injection equipment adapted to the type of soil
  • Drilling units using strings equipped with an injection system
  • The injection procedure itself is done using various consolidation additives (cement, premix, polyurethane) depending on the purpose of the application
  • Also the pressure and the mode of injection [“unitary and global” under low pressure or I.G.U. mode (« Injection Globale et Unitaire ») or multi-step “repetitive and selective” under high pressure or I.R.S. mode (“Injection Répétitive et Sélective”)] depend on the expected result and the technical specifications

1. First phase of the drilling and injection according to the spacing of grout holes in the 'primary grid' pattern

2. Subsequent, second drilling phase in line with the 'secondary grid' pattern or half-size grid with a tighter mesh pattern, according to the nature of the soil and the project-specific requirements

In advance set up of continuous electronic monitoring of the various grout injection parameters, to be verified from the very start of the project and eventually to be refined in function thereof.  

Construction chart

Injections grid

Fields of application

• Filling of cavities

• Consolidation of the soil: increasing the mechanical resistance of the injected areas

• Permeability: lowering the water permeability of the soil

Environmental impact

• Vibration-free

• Removal of spoil (drilling mud)

• Limited noise pollution

• Monitoring of adjacent buildings.

Technical specifications

• Wide range of drilling techniques tailored to adapt to various types of soil to be treated

• Wide range of injection grouts according to the purpose and the desirable effect of the injection, e.g. consolidation or permeability.

Related projects for this technique

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