Wave-induced pore pressure gradients can lead to the momentary liquefaction of sandy sediments, potentially enhancing coastal erosion. This study investigated pore pressure gradients in a large-scale flume experiment replicating pre-Hurricane Sandy beach profiles in New Jersey under different wave conditions. Sediment samples collected along the profile have a median grain size of 0.3 mm-0.42 mm and were classified as sand with fines (SC or SM). More offshore samples were well-graded, while the sample collected farthest towards the shore was poorly graded. Pore pressure was measured using three vertical pressure sensor stacks during three experimental phases with varying forcing conditions. Results showed a substantial excess pore pressure attenuation of, on average, 37.4% in the uppermost 10 cm of the sediment, and 79.2% 30 cm below grade. Relationships have been identified between relative density, measured using a portable free-fall penetrometer, and various wave-induced pressure metrics, including maximum instantaneous excess pore pressure, wave skewness and asymmetry, the 30-min pressure difference, and significant wave height. These findings assist with enhancing the understanding of pore pressure response to wave action and possible resulting impacts on erosion related to momentary liquefaction.
