How can grouting improve the seismic performance of deep foundations?

2 Types of grouting

Different types of grouting can be used for deep foundations, depending on the purpose, material, and method of injection. Compaction grouting uses a stiff cement-based material to displace and densify the soil without penetrating it, and is often used to improve bearing capacity and settlement resistance. Permeation grouting uses a low-viscosity cement-based or chemical-based material to fill the soil or rock pores, and is used to improve stiffness and strength. Jet grouting uses a high-pressure jet of water, air, and cement-based or chemical-based material to erode and mix with the soil or rock and form a column or panel around the foundation. Fracture grouting uses a high-pressure injection of cement-based or chemical-based material to create or enlarge cracks in the soil or rock and fill them, often to reduce seismic stress or strain. All these methods can help you achieve your desired outcome for your foundation.

3 Benefits of grouting

Grouting can offer a number of seismic performance benefits for deep foundations, such as increasing stiffness and strength, enhancing durability and stability, reducing the potential for liquefaction or lateral spreading, and improving drainage and consolidation. This can lead to a reduction in dynamic response and vibration of the structure, increased resistance to seismic forces, prevention of deterioration or buckling of the foundation, reduced pore water pressure and increased effective stress of the soil, and increased shear strength.

4 Challenges of grouting

Grouting can be a complex and costly addition to deep foundation projects, as it involves additional materials, equipment, labor, testing, and quality control. Additionally, grouting introduces a certain amount of uncertainty and risk due to the accuracy and reliability of the site investigation, the grouting material properties, the injection parameters, and the verification methods. Moreover, grouting may have environmental or social impacts such as noise, vibration, dust, groundwater contamination, or land subsidence. Finally, grouting can interfere with other underground structures or utilities by damaging or displacing them.

5 Best practices for grouting

To achieve the best possible results from grouting, it is important to conduct a comprehensive site investigation and characterization, including geotechnical, geological, hydrological, and seismic aspects. The appropriate type, material, and method of grouting should be selected based on the design objectives, the foundation type, and the site conditions. Laboratory and field tests should be performed to determine the grouting material properties, the injection parameters, and the groutability of the soil or rock. Additionally, a quality assurance and quality control program should be implemented with monitoring, testing, and verification of the grouting process and performance. Finally, the effectiveness and efficiency of grouting should be evaluated to consider its benefits, challenges, and costs.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?