Types of Jet Grouting Methods

Soil Improvement in Geotechnical Engineering

Soil improvement is a fundamental aspect of geotechnical engineering aimed at enhancing bearing capacity, reducing settlement, and improving structural stability. This process is especially critical in areas where soil suffers from structural weaknesses. Common soil improvement methods include dynamic compaction, grouting, jet grouting, deep soil mixing, and stone columns, each selected based on soil type and project conditions.

One of the most effective methods in this field is jet grouting, which improves the soil structure by injecting high-pressure cement grout, forming a solidified and resistant mass. This technique is especially used for excavation support, permeability reduction and waterproofing, and enhancing soil bearing capacity.

A notable example of its successful application was in stabilizing subway lines in Tokyo, where jet grouting significantly improved the ground’s load-bearing capacity and prevented potential settlement.

Historical Development and Global Applications

Like any engineering technique, jet grouting has evolved through time, research, and experience. Generally, jet grouting is categorized into single-fluid, double-fluid, and triple-fluid systems. Figure 1 illustrates a schematic of these methods. The following sections explore the method’s evolution and international application history.

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The first single-fluid jet grouting system, known as the Chemical Churning Pile (CCP), was developed in the early 1970s in Japan. Around the same time, the Jumbo Special Pile (JSP) emerged in 1972, considered a precursor to today’s double-fluid systems. Although Japan led the innovation, other countries such as the U.S., China, Italy, and France began adopting jet grouting in the late 1970s to tackle complex geotechnical issues.

By the late 1980s, the increasing popularity of jet grouting highlighted challenges—particularly the limited diameter of columns formed using the single-fluid method. This prompted the development of more advanced systems.

In the 1990s, triple-fluid systems were introduced, allowing for larger diameters, better quality control, and adaptability across various soil types. Figure 2 depicts this method’s evolution.

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Single-Fluid Jet Grouting System

The single-fluid jet grouting method uses high-pressure cement grout to form soil-cement columns. The grout is injected through nozzles, causing in-situ soil mixing and stabilization. This method is praised for its simplicity and effectiveness, especially in soft or granular soils.

This method was first implemented in China in the late 1970s in Shanghai for excavation support. It was also used in the U.S. for tunnel stabilization and riverwalk reconstruction projects in Texas. Italy also applied it in bridges, tunnels, and embankment stabilization projects.

Its compact nature makes it ideal for underground waterproofing, where compressed air is impractical. However, challenges include inconsistent column diameters and limited performance in cohesive soils, leading to the development of the triple-fluid system.

Triple-Fluid Jet Grouting System

Triple-fluid jet grouting involves injecting water, air, and cement grout to create larger, more durable soil-cement columns. It enables better control over soil disintegration and has become popular in large-scale projects.

Developed in the late 1980s, it has spawned variants such as:

  • Rodin Jet Pile (RJP) – Introduced in 1996, uses dual-stage destruction with water/air and cement-air mix.

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  • X-Jetting – Uses high-pressure water surrounded by air to disintegrate soil before injecting low-pressure grout.

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  • Ultra-Jetting System (UJS) – Developed in Korea, uses inclined high-pressure water/air followed by cement grout; ideal for diameters up to 2.5m.روش جت گروتینگ سه سیاله

  • Twin-Jet Method – Combines rapid injection and instant hardening using catalysts like sodium silicate for urban tunneling and foundation reinforcement.

Despite its high performance, this system generates considerable waste, posing environmental and disposal challenges.

Double-Fluid Jet Grouting System

The double-fluid system simultaneously injects high-pressure grout and air, creating stable soil-cement structures. Its cost-effectiveness and broad applications led to peak popularity in the 1990s.

Later, Super Jet Grouting emerged in Japan, enhancing column quality and size by increasing grout volume and optimizing air pressure. First used in China’s Xiaolangdi Dam project in 1995, it was later adopted in U.S. tunneling projects, significantly reducing project costs.

While it’s not ideal for foundations or cohesive soils, Super Jet Grouting offers the largest column diameters and superior mixing capabilities compared to other systems.

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Conclusion

Jet grouting is a powerful and versatile soil improvement technique used in various civil engineering applications such as dams, tunnels, diaphragm walls, and excavation support. By injecting grout under high pressure, it forms strong columns or barriers that enhance soil strength and stability.

Among the widely used types—single-fluid, double-fluid, triple-fluid, and Super Jet Grouting—each has specific advantages, limitations, and costs. For example, single-fluid is cost-effective and suitable for smaller projects with soft soils, while triple-fluid excels in forming large-diameter, high-quality columns for complex conditions.

A comparative analysis based on injection pressure, column diameter, costs, and limitations helps engineers select the optimal jet grouting method. Table 1 summarizes this comparison based on real-world case studies and practical experiences.

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