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.
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.
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Common uses
- Re-level structures
- Stabilise and mitigate the settlement of overlying structures during tunnelling
Advantages
- 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
Quality assurance
Keller can provide complete solutions which combine fracture grouting with real-time monitoring of affected structures.
Extensive experience has allowed us to develop advanced drilling and computerised grouting systems that integrate the grouting injection process and real time monitoring. Grout injection data is plotted against time and summarised in three dimensional plots and reports.
Related techniques
Related projects
Infrastructure
Crossrail C310
Crossrail was in its day the largest construction project in Europe. It involved the construction of 42km of twin underground railway tunnels and 10 new stations across 40 construction sites.
Infrastructure
Crossrail C300/C410
Crossrail is the largest construction project in Europe. It involves the construction of 42km of twin underground railway tunnels and 10 new stations across 40 construction sites.