Acoustic emission induced by sand liquefaction during vibration loading

Area of Science:

• Geotechnical Engineering
• Soil Mechanics
• Acoustic Emission

Background:

• Soil liquefaction is a critical phenomenon in geotechnical engineering, particularly in seismic events.
• Understanding soil behavior under cyclic loading is crucial for infrastructure safety.
• Acoustic emission (AE) offers a non-destructive method to monitor internal soil processes.

Purpose of the Study:

• To investigate the acoustic emission (AE) characteristics of poorly graded sands with varying grain content during liquefaction.
• To correlate AE parameter behavior with distinct stages of sand behavior before, during, and after liquefaction.
• To determine the influence of sand grain content on the onset and duration of liquefaction.

Main Methods:

• Experimental analysis of poorly graded sand samples with controlled grain size distribution.
• Application of acoustic emission (AE) monitoring during cyclic loading to induce liquefaction.
• Observation and analysis of AE parameters (e.g., energy, counts) in relation to pore pressure and confining stress.

Main Results:

• A distinct V-shaped behavior was observed in AE parameters, corresponding to three stages: microfracturing (Phase A), AE silence (Phase B), and intense grain friction (Phase C).
• Sand grain content significantly affects AE parameter evolution and liquefaction dynamics.
• Transitioning to "extremely poorly graded sand" prolonged liquefaction onset, while coarser grains required longer vibration durations to reach liquefaction.

Conclusions:

• AE monitoring effectively characterizes sand behavior during liquefaction, with distinct phases linked to pore pressure and grain interactions.
• Sand grain content is a key factor influencing liquefaction susceptibility and the time required to reach the liquefied state.
• The findings enhance the understanding of soil dynamics and provide insights for seismic hazard mitigation and foundation design.