Pore Water Pressure Behavior during Liquefaction Based on Shaking Table Testing

Abstract

Liquefaction is a critical geotechnical hazard that occurs when excess pore water pressure builds up in saturated sandy soils during earthquakes, leading to a significant reduction in effective stress and shear strength. This study investigates the behavior of pore water pressure during liquefaction using shaking table tests on a laboratory-scale saturated sand model with an initial relative density of 40%. Sinusoidal horizontal excitations were applied with peak ground accelerations (PGA) of 0.3 g, 0.4 g, and 0.5 g for a duration of 60 seconds. Excess pore water pressure was continuously monitored using piezometer sensors installed at depths of 100 mm, 300 mm, and 500 mm to capture depth-dependent responses. The results reveal a nonlinear relationship between PGA and pore water pressure response. The highest excess pore water pressure (Δu) and pore water pressure ratio (ru) were recorded at PGA = 0.3 g, particularly at greater depths, indicating that moderate seismic loading promotes pore pressure accumulation under limited drainage conditions. At higher PGA levels (0.4 g and 0.5 g), pore water pressure did not increase proportionally, suggesting the influence of cyclic soil densification and accelerated dissipation mechanisms. Temporally, the pore water pressure response can be divided into three phases: rapid buildup, peak response approaching liquefaction, and subsequent dissipation. These findings demonstrate that liquefaction potential cannot be evaluated solely based on earthquake acceleration intensity, but must also consider soil depth, density, and drainage characteristics, providing useful insights for liquefaction risk assessment and mitigation.

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