Soils often need treating to support the weight of a building or to withstand the loads imposed by a piece of infrastructure. This can mean improving the ground or putting in foundations to transfer the loads to deeper more competent layers.
- Increase bearing capacity
- Reduce settlement and permeability
- Mitigate liquefaction
- Increase slope stability
- Collapse / fill voids, stabilize mines / karst
- Accelerate settlement
- Treat expansive soils
- Stabilize soft ground
The mechanism of achieving ground improvement varies by technique and soil conditions. Densification by means of vibration or displacement is an effective means of improving granular soils. Reinforcement involves constructing or inserting stiff elements within a soil mass to create an improved composite material. Soil can be improved by adding cementitious materials by either permeation in granular soils or mixing in all soil types. The insertion of vertical drains decreases the amount of time it takes soils to settle and strengthen when subjected to a surcharge load.
Voids can cause overlying structures to settle. Compaction grouting, cement grouting, polyurethane grouting, and other specialized grouting techniques permanently fill voids. Keller has experience with the full range of void filling techniques to stop mine subsidence and stabilize sinkholes.
Heave due to expansive clay soils is a common problem in some areas of the US. Injection systems treat expansive clays beneath buildings and landfills with the pressure injection of an aqueous solution of water, lime or lime/flyash slurry, or potassium chloride. Water injection pre-swells expansive clays prior to construction. Lime injection fills the desiccation pattern of expansive clay with slurry and stabilizes the surface of the pad for workability, for building pads, streets, parking lots, and runways. Lime/flyash injection improves low-strength soils to improve bearing capacity and/or trafficability of runways, landfills, and bridge approaches. Potassium chloride injection arrests heave occurring beneath existing structures by limiting the amount of water underlying clays can absorb. Keller has experience with the full range of ground improvement techniques.