Jet Grouting uses high velocity fluid jets to construct cemented soil of varying geometries in the ground.

Jet grouting technique illustration

Common uses

Control of groundwater or excavation of unstable soil (water-bearing or otherwise)
Underpin foundations
Provide excavation support
Seal the bottom of planned excavations

Process

Jet grouting creates in situ geometries of soilcrete (grouted soil), using a grouting monitor attached to the end of a drill stem. The jet grout monitor is advanced to the maximum treatment depth. Then high velocity jets (cement grout with optional water and air) are initiated from ports in the monitor. The jets erode and mix the in situ soil with grout as the drill stem and monitor are rotated and raised.

Depending on the application and types of soils, one of three variations is used: the single fluid system (slurry grout jet), the double fluid system (slurry grout jet surrounded by an air jet) and the triple fluid system (water jet surrounded by an air jet, with a separate grout port). The jet grouting process constructs soilcrete panels, full columns, or partial columns with designed strength and/or permeability.

The soilcrete geometry and physical properties are designed based on the in-situ soils. Because it is an erosion-based system, soil erodibility plays a major role in predicting geometry, quality, and production. Cohesionless soils are typically more erodible by jet grouting than cohesive soils.

Advantages

Effective across the widest range of soil types of any grouting system, including silts and most clays
Ability to construct soilcrete in limited spaces and around subsurface obstacles such as utilities
Low headroom equipment enables construction in limited spaces such as basements
Can target specific soil layers at depth without having to treat soils above
Jet grouting can be combined with other techniques to provide a comprehensive and cost-effective geotechnical solution
Can usually be done without disrupting normal facility operations
Containerized, highly mobile support equipment reduces mobilization and demobilization costs and time

Quality assurance

To meet the intent of the project and ensure that the jet grout program is successful, an in situ test program is generally installed prior to production. Based on review of the project borings, the application, and previous project experience, initial jet grout parameters (or sets of parameters) are established and executed in the field for the test program. The test program will specifically demonstrate the column spacing, overlap, and geometry of the jet grouted elements. The test program will also verify consistency of the grout batching, evaluate the equipment functionality, and confirm the real-time recording and reporting of the jet grout parameters. All of these processes are used to establish a standardized protocol for each specific soil type that is consistent and repeatable for the production columns.

Keller’s proprietary data acquisition (DAQ) system enables us to continuously monitor and record specific jet grout parameters at the rig. The DAQ interface provides real-time information to the drill rig operator, while the column construction data is uploaded wirelessly to a server soon after completion to be used for report generation. These reports can then be reviewed in near real-time by project management and submitted to the client.