Construction Technology of High-Pressure Jet Grouting Pile

Process Principles and Design Requirements

1. Reinforcement Principle

The high-pressure jet grouting method uses the drilling rig to drill the grouting pipe with the nozzle into the predetermined position of the soil layer and makes the slurry or water and (air) become 20 ~ 40 MPa high-pressure jet from the nozzle, punching, disturbing and damaging the soil. At the same time, the drill pipe gradually increases at a certain speed, and the slurry is forced to mix with the soil particles. After the slurry is solidified, a cylindrical consolidation body (i.e. rotary jet pile) is formed in the soil to achieve the purpose of strengthening the foundation or water sealing and seepage prevention.

According to different injection methods, injection grouting can be divided into single pipe method, double pipe method, and triple pipe method.

Single?pipe?method:?single layer injection tube, only injection cement slurry.

Double pipe method:?also known as the slurry gas injection method, is the use of double grouting pipe at the same time the high-pressure cement slurry and air two kinds of the medium jet transverse jet ejection, impact damage soil. Under the combined action of the high-pressure slurry and the airflow around the outer ring, the energy of the damaged soil increases significantly, and finally, a large consolidation body is formed in the soil.?

The triple pipe method?is a kind of slurry, water, and air injection method, which uses triple grouting pipes conveying water, air, and slurry respectively. A cylindrical airflow is surrounded by high-pressure water generated by high-pressure generating devices such as high-pressure pumps, and high-pressure water jet flow and air coaxial jet flow are carried out to cut the soil, forming a large gap. Then the cement slurry is injected into the cut and broken foundation at low pressure by the slurry pump. The nozzle is rotated and lifted so that the cement slurry and soil are mixed, solidified in the soil, and a large consolidation body is formed. The solidifying diameter can reach 2 m.