PROOF OF CONCEPT OF A RESOURCE-SAVING SOIL IMPROVEMENT TECHNIQUE FOR LIQUEFACTION MITIGATION

Saturated layers of loose soils, primarily sands with a minor content of silt, are critical subsoil conditions in many cases, due to their susceptibility to liquefaction under dynamic loads such as seismic events. Liquefaction is characterized by an increase in pore water pressure that reduces effective stresses to zero, resulting in a loss of soil strength and a liquid-like behaviour until the excess pore pressure dissipates over time. There are a variety of liquefaction mitigation methods available, which are based on different approaches, such as an increase of strength (e.g., grouting), an increase of permeability (drainage), and an increase of relative density (densification). The extensive use of raw materials and the heavy machinery of conventional methods are the primary contributors to high carbon emissions, emphasizing the need for an innovative, resource-saving improvement technique.

In this soil improvement concept, the densification of the soil is achieved by dynamically applying pressure surges on the water to increase the pore pressure up to a level where it reaches the magnitude of the effective stresses, generating a localized liquefaction. Consequently, the soil behaves almost like a liquid until the excess pore pressure dissipates, allowing the particles to rearrange into a denser state and thereby reducing the liquefaction potential. The current paper introduces the concept and experimental results of a small-scale test box using various measurement devices, such as pore pressure sensors, accelerometers, and a particle image velocimetry camera, to analyse the soil’s response during and after the applied impulses. These tests lay the groundwork for future laboratory tests and the subsequent development of a practical system for field tests.