Jet Grouting creates in-situ columns of grouted soil using high-pressure grout injection. Grouting is performed by pumping high-velocity jets of grout (or sometimes grout and air or grout, water, and air) through the side of a grout monitor, attached at the end of the drill string. The jets erode and mix the soil as the drill string and the monitor is rotated and withdrawn.
The jet grouting process constructs jet grout panels, full or partial columns with designed strength and permeability. Jet Grout column size is dependent on soil type, soil density, injection pressures and flow rates of the various fluids employed, rotation speed, lift rate and type of system used. This process can also be used to construct seepage barriers or can find its application in ground treatment/modification.
It is the best practice to perform a pre-construction test program to calibrate, adjust and verify jet grout parameters and the design.
Single fluid jet grouting (cement only)
The single fluid system is the simplest. This simplicity is due to exclusive reliance on the high velocity of the jetstream to cut, remove and mix the in-situ soil.
Double fluid jet grouting (cement with air)
The double fluid system simultaneously injects a high-velocity grout stream within a cone of compressed air. The double-fluid system is capable of creating a larger column compared to the single-fluid system.
Triple fluid jet grouting (cement with air and water)
The triple fluid system is the most complicated jet grouting system due to the simultaneous injection of three different fluids, air, water, and grout. The triple fluid system can create the largest diameter of the column among the three types.
Jet-grouting technology is an easy and safe installation process without unwanted disruption to other operations. This often results in reduced construction time and eliminates ground vibration often associated with other soil improvement technologies when compared to alternate and competing systems. This benefit is of particular importance in dense urban environments where unwanted vibration during construction may damage the surrounding facilities.
Jet grouting can be advantageous in the following applications:
- cut-off wall
- shoring (temporary and permanent) & vertical shaft;
- underpinning of existing structures
- tunnel liners.
- Construction of horizontal barriers
- Control of groundwater
- Support for excavation
- difficult logistic conditions
- confined spaces & presence of obstacles to cross
- high-depth treatment with crossing of voids