Jet grouting, a highly effective ground improvement technique, involves the in-situ mixing of soil with injected cement grout to form cement-stabilized soil columns. This process results in enhanced strength and reduced permeability of the stabilized soil, making it an ideal engineered product for foundation support and groundwater control. It finds common applications in underpinning existing structures and creating cutoff walls for excavation support.
The procedure begins with the drilling or jetting of a small-diameter pipe, typically around 4 inches in diameter, to reach the desired treatment depth. At this point, contractors initiate the injection of a neat cement grout under high pressure, typically around 6,000 psi. This injection occurs through ports located at the bottom of the drill pipe while simultaneously rotating and withdrawing the pipe. The rotational movement and withdrawal rate can be adjusted to vary the diameter of the resulting jet grout columns.
These treated soil columns are strategically placed to provide vertical support or overlapping to form walls or barriers, effectively limiting the horizontal movement of weak soil and groundwater. Through precise control and meticulous quality assurance, jet grouting delivers remarkable results in terms of soil stabilization and hydraulic control.