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Terms and definitions of Jet Grouting

Terms and definitions of Jet Grouting

Jet Grouting

The jet grouting process consists of the disaggregation of the soil or weak rock and its mixing with,

and partial replacement by, a cementing agent; the disaggregation is achieved by means of a high energy jet

of a fluid which can be the cementing agent itself .

Jet Grouted Elements

A volume of soil treated through a single borehole. The most common elements are :

_ jet grouted column : a cylindrical jet grouted element ;

_ jet grouted panel : a planar jet grouted element .

Jet Grouted Structures

An assembly of jet grouted elements which are partially or fully interlocked. The most common structures formed are :

_ Jet grouted diaphragm : a wall structure  ;

_ Jet grouted slab : a horizontal structure formed by essentially vertical jet grouting  ;

_ Jet grouted canopy : a structure formed by horizontal jet grouting  ;

_ Jet grouted block : a three-dimensional structure. 

single system

The jet grouting process in which the disaggregation and cementation of soil are achieved by a high energy jet of

a single fluid, usually a cement grout .

Double (air) System

The jet grouting process in which the disaggregation and the cementation of soil are achieved by one high energy fluid

(usually a cement grout) assisted by an air jet shroud as a second fluid .

Double (water) System

The jet grouting process in which the disaggregation of the soil is achieved by a high energy water jet and its cementing

is simultaneously obtained by a separate grout jet .

Triple System

The jet grouting process in which the disaggregation of the soil is achieved by a high energy water jet assisted by an air jet shroud,

and its cementing is simultaneously obtained by a separate grout jet .

NOTE : In special cases the water can be substituted for other appropriate liquids or suspensions .

Horizontal Jet Grouting

treatment performed from a horizontal or sub-horizontal borehole (within ± ۲۰° from the horizontal plane) .

Jet Grouting Rig

Rotary rig able to automatically regulate the rotation and translation of the jet grouting string and tool .

Jet Grouting String

Jointed rods, with simple, double or triple inner conduit, which convey the jet grouting fluid(s) to the monitor .

Monitor

The tool mounted at the end of the jet grouting string, to enable jetting of the fluids into the ground .

Nozzle

A specially manufactured device fitted into the monitor and designed to transform the high pressure fluid flow in the

string into the high speed jet directed at the soil .

Radius of Influence

Effective distance of disaggregation of soil by the jet, measured from the axis of the monitor .

Spoil Return

The surplus mixture of soil particles and introduced fluids arising from the jet grouting process, and normally flowing

to the ground surface via the annulus of the jetting borehole .

Jet Grouting Parameters

The jet grouting parameters are defined :

_ pressure of the fluid(s) within the jet grouting string ;

_ flow rate of the fluid(s) within the jet grouting string ;

_ grout composition ;

_ rotation speed of the jet grouting string ;

_ rate of withdrawal or insertion of the jet grouting string .

Prejetting

The method in which the jet grouting of an element is facilitated by a preliminary disaggregation phase, with a jet of

water and/or other fluids.

NOTE : Prejetting is also widely known as prewashing or precutting .

Fresh-In-Fresh Sequence

The sequence of work in which the jet grouted elements are constructed successively without waiting for the grout

to harden in the overlapping elements .

Primary-Secondary Sequence

The sequence of work in which the execution of an overlapping element cannot commence before a specified hardening time

or achievement of predetermined strength of the adjacent elements previously constructed .

Jet Grouted Material

The material which constitutes the body of a jet grouted element .

Reinforced Jet Grouting

Jet grouted columns reinforced by steel or other high strength material .