January 30, 2021
It is a kind of drilling tool used to transport mass such as slurry night, compressed air, and water. Under the working conditions of high pressure, it can ensure continuous dynamic density and static density. According to the different hole formation and use methods, it is divided into a single rotary jet, double rotary jet, and triple rotary jet.
Main components: The jet drilling rig is mainly composed of a drill pipe, distributor, bit, anti-loosening device, cushion fork, and variable diameter joint.
In many places of the world, soil improvement methods like jet-grouting are employed. It entails combining in-situ soil with water-cement grout, which is then injected into the soil using specialized equipment at high speeds of over 200 m/s (656 ft/s) and high pressures ranging from 30 to 60 MPa (4500 to 9000 psi). After being introduced to British Columbia in 2004, jet-grouting has since been used effectively in the Lower Mainland for a number of temporary and long-term soil enhancement applications.
The technology was historically created in Japan in the middle of the 1970s and imported into Europe in the decade that followed. This technology spread fast throughout Europe, especially in northern Italy (due to soil conditions particularly suitable for jet-grouting, made up of alluvial soil with sand and gravel). The use of jet-grouting has increased recently in North America as well. Papers on jet-grouting technology were the main topic of discussion at the most recent grouting conference, which took place in 2003 in New Orleans and is held every ten years.
Introduction to the technology of jet grouting
As previously indicated, grout is pumped into the ground using a jet grouting technique at extremely high pressure and speed. The jet, which is produced at the base of the drilling rods, simultaneously infuses a water-cement mixture into the soil while eroding the native soil matrix. The jetting starts once the drilling rod has been lowered to the necessary depth in the earth. The rod is then raised while rotating and moving at a steady speed.
The result is a series of grout columns resembling structures.
The typical size and shape of a built-in jet-grouted column are influenced by a number of factors. These are chosen by the designer and managed in the field.
The jetting technique used will determine the grout mix pressure, air and water pressure, diameter and number of nozzles (placed on the drilling rod), the composition of the grout mix, rod withdrawal rate, and rotation speed.
Types of jet-grouting
Three basic system types are typically employed in jet grouting.
Single fluid
In this procedure, the same grout mix is used to disaggregate the soil and mix it with the grout.
Double fluids
For this technique, the grout mix immediately disaggregates the soil and mixes it with the grout mix, with the help of coaxial air jetting to boost the delivery energy.
Triple fluids
Soil disaggregation for triple-fluid systems is accomplished directly by high-speed water pressure and coaxial air jetting. The grout mixture is injected at a lower jet pressure from a nozzle beneath the air/water nozzle to generate the mixture. The grout mixture is injected into the already-eroded soil in this manner.
