Compensation or fracture grouting is the injection of a cement slurry grout into the soil creating and filling fractures that then lift the overlying soil and structures.

Typical applications

  • Re-level structures
  • Stabilise and mitigate the settlement of overlying structures during tunnelling

Process

A pipe with rubber sleeves covering ports is inserted into a pre-drilled hole beneath a structure and grout injected under pressure at strategic locations through the ports.

Once the hydrofracture pressure of the soil is exceeded, fractures open in the soil and are immediately expanded by the influx of grout. This results in the controlled heave of the overlying soils and structures.

Key benefits

  • Unobtrusive, as it can be done from shafts or tunnels without access to affected buildings.
  • Precise control and reporting when linked to an effective monitoring system.