A typical use of stabilisation injection is to give temporary support to a structure, shaft or heading. Alternatively, the material can be used to fill voids, or to stop fast leaks of water or flowing sand.
For temporary works or to stabilise flowing sand, polyurethane (PU) is injected into the ground around a heading or shaft. The area can then be dug out, considerable reducing the risk of collapse. As an example, this process has successfully been applied in creating temporary piles under a scoured out bridge foundation to give time for the main strengthening works.
The PU can also be injected through a hollow bar creating a mini pile. Due to the small size of the pumps, this allows access where it is not possible for a drilling rig to attend.
Another technique is to use an acrylic resin, which is fire retardant . This allows for a hole to be cut out of the secant piling using a gas axe without the material catching fire.
Fast leak injection uses similar material injected to form a plug behind the leaking area.
Void filling can be carried out by either using PU material only, or a mixture of structural polystyrene and PU only filling in gaps to the soffit. The expanded material is inert and can be removed easily if required. During injection, there is no need for structural shuttering as the material is self-supporting.
- Can be easily removed
- Can be fireproof
- Can use high or low pressure (site dependent)
- Good chemical resistance against road salts
- All quantities can be measured and recorded
- All work from below or above
- Retaining walls
- Steel piles for cutting out
- Stopping fast leaks
Health & Safety / Environmental
- Solvent free
- Good chemical resistance
- No special PPE required
- No specific storage or containment required
- Hiams Road bridge, Cambridge Council
- Denmark Road tunnel, Nomenca
- Ogden Reservoir, Yorkshire Water, J.N.Bentley
- DSJV for CrossRail Crossover 13, fast leaks
- Qatar Doha: Qatar Rail, Gold Line, Red Line South. Repairs of fast leak due to local geology and head interventions.
- Acrylic resin > TamAcryl 2000
- Polyurethane > TamPur 117/ TamPur 110
Application Conditions & Limitations
- The acrylic resins have permanent open times until an accelerator is added, giving maximum flexibility.
- Polyurethane is injected at the same time as the catalyst, and will set in minutes/ seconds, depending on the amount of catalyst added.
- All the acrylic and polyurethanes are affected by low temperatures, which usually slow down the reaction time.
- Any structure with missing pointing or cracking likely requires either surface repair or waterproofing with the thicker polyurethane, to avoid the material running out.
- There is a risk of jacking
Previous Site Environments
- Confined space
- Over a water course with EA approval
- Tunnel under a reservoir
- Unrestricted traffic
- In a pit formed for a tunnel boring machine