Double-Tube Jet Grouting Rig

The double-tube rotary jet grouting rig is one of the core pieces of equipment used to construct water-stop curtains. In simple terms, the "double-tube rotary jet grouting rig" is the "tool" that implements the technique, while the "water-stop curtain" is the ultimate engineering "objective" to be achieved.

Process and Objective

· Double-Tube Rotary Jet Grouting Rig (Tool): This is a rotary jet grouting rig that perform a double-tube process. During drilling, it uses a high-pressure grout pump to inject high-pressure cement slurry and compressed air through a double drill pipe (inner pipe for slurry delivery, outer pipe for air delivery). The high-pressure jet cuts, mixes, and partially replaces the soil, forming a cylindrical cemented soil mass (jet grouting pile).

· Water-Stop Curtain (Objective): Through the construction work of the rig,  series jet grouting piles are arranged to interlock and overlap with each other according to the design, ultimately forming a continuous, dense underground diaphragm wall underground. This wall can effectively block the seepage path of groundwater, providing waterproofing and seepage control. It is a key safety guarantee for underground works such as deep excavations and tunnels.

Therefore, the "double-tube rotary jet grouting rig" is one of the primary construction machines used to achieve the "water-stop curtain" objective.

How the Double-Tube Rotary Jet Grouting Rig Works

The double-tube rotary jet grouting rig combines the functions of drilling and jet grouting. Its typical working process is as follows:

1. Drilling: The rig starts by drilling to the designed depth.

2. Jet Grouting and Lifting: When the drill bit gets to reach the predetermined depth, it starts to jet the high-pressure cement slurry and compressed air through the nozzles, the drill pipe rotates and it is being lifted slowly at a pace.

3. Formation of the Pile: The high-pressure jet erodes and breaks-up the soil mass and mixes it forcibly into the cement slurry.  After solidification, a jet grouting pile of relatively large diameter is formed.

Common Jet Grouting Methods

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Engineering Application Scenarios

This equipment and its techniques are widely used in various engineering projects requiring groundwater control, for example:

· Deep Excavation Support: Constructing a water-stop curtain around the perimeter of an excavation before digging begins to prevent groundwater from flowing into the pit.

· Tunneling and Underground Works: Forming a pre-support and waterproofing layer outside the tunnel excavation profile to prevent face collapse and surface settlement.

· Dam and Levee Seepage Control: Used for seepage control in the reinforcement of major river dams and levees.

Significant Note: The construction of jet grouting pile water-stop curtains in geological formations similar to those above a water-rich sand layer, or in the presence of large fractures or karst caves is highly challenging from a technical standpoint. Special measures are required to ensure the effectiveness of the water cutoff. The choice of which method (single-tube, double-tube, or triple-tube) to use depends primarily on the geological conditions, the required design strength, and the waterproofing requirements.

Nancy Fan   July 9, 2026