What is Jet Grouting?

Jet-grouting is a process of creating “soil concrete columns” or jet grouted columns in place with a stabilizing grout mix delivered under high pressure and flow through nozzles  at the end of a monitor inserted in a borehole. The soil concrete column is created by rotating and lifting the monitor at a precalculated slow, smooth, constant speed, cutting the soil with water and/or air while tremie-feeding an engineered grout slurry at high pressures through the base of the monitor to achieve thorough mixing and a consistent geometry and quality soilcrete columns.
The common uses for jet-grouting are to underpin foundation, to seal the bottom of planned excavation and to provide support on the excavation.
Jet-grouting system can stabilize foundations, provide barriers, and gives excavation support.
Jet-grouting ground improvements finds application for the following:

 

●       Horizontal barriers
●       Groundwater control
●       Tunneling
●       Support excavation
●       Underpinning

What are the Advantages of Jet-Grouting?

One of the main advantages of jet-grouting is that it is less dependent on soil type than most other grouting methods. Because it physically mixes the soil with a stable fluid rather than permeating or displacing. It can be utilized in stabilizing most clays, bay mud, peat, silts, sand and some gravely soils.
One of the main advantages of jet-grouting is that it is less dependent on soil type than most other grouting methods. Because it physically mixes the soil with a stable fluid rather than permeating or displacing. It can be utilized in stabilizing most clays, bay mud, peat, silts, sand and some gravely soils.

 

Here are some other advantages of Jet-Grouting:

 

●       Can be accomplished on limited spaces
●       Provides unique design flexibility
●       Can accomplished a high cement grout column without causing an enormous ground disturbance.
●       Can stabilize soil foundations
●       Provide Barriers
●       Rapid installation
●       Increase bearing capacity

 

Variations for jet-grouting depends on the application and type of soil on a certain location. Mainly the available techniques are grouped in three main systems namely:

 

Single Fluid jet grouting
●       Or so called the (slurry grout jet and single fluid system), in this method the grout is injected to the ground through one nozzle. The jetting fluid performs functions of loosening the soil, and excess removing that the material itself becomes viscous to raise towards the ground hole or collar.

 

Double Fluid jet grouting
●       Or so called the (slurry grout surrounded by an air jet), in this method a high velocity jet grout is encased in a cone of air, in which the air improves the removing of the excess in situ soil and lifted it to the collar by air.

 

Triple Fluid jet grouting
●       Or so called the (water jet surrounded by an air jet, with a separate grout port), in this method the soil remolding and the cementation are definitely separated. The soil loosens by a high velocity water, jet and air. The water with cement grout are taken on a different nozzle apparently placed on the lower part of the monitor or nozzle. The main purpose of the grout is to cement the soil that is initially remolded by water jet.
JetGrouting-fluid

Project Design for Jet-Grouting

Design specifications to create soilcrete columns are achieved using proper parameters. The parameters include; grout pressure, rotation and lifting speed, number and diameter of nozzles, c/w ratio and specifications of the site-specific soil. Different soil types must use different jet grouting parameters.

 

Parameter Design Example:

 

Parameter
Range
Typical
Borehole diameter (mm)
76-115
Number of Nozzles
1-3
2
Grout pump pressure (MPa)
30-50
40
Grout slurry (cement/water)
0.5-1,2
1,0
Rotation rate (rev/min)
10-30
20
Withdraw rate (sec/m)
100-250
150
Cement rate (kg/m3)
430-590

Get in touch!

Contact the specialists at Geo Grout Ground Modification Specialist Inc. of Western United States for your jet-grouting project needs. Call us at (650) 241-2400 for complete information on our jet-grout services or email us at sales@www.gggms.com to discuss your Jet-Grouting needs today.

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