Correlation of pore pressure and dissipated energy in earthquakes - field verification

Technical Abstract

The possibility of a correlation between dynamic pore pressure increase (p) and dissipated energy density (D) in soils subjected to earthquake shaking has been the subject of speculation for nearly twenty years.

While cyclic loading tests have tended to confirm the D-p hypothesis in the laboratory, no field confirmation has been given. The research reported here focuses on field verification for the D-p hypothesis using existing acceleration and pore pressure recordings for downhole arrays.

Downhole acceleration records from five different earthquakes are used to calculate continuous representations of shear stress and strain in the soils involved. These stress-strain records are then integrated to obtain time histories of dissipated energy density for comparison with measured pore pressure data. Remarkably good correlations of measured pore pressures with scaled energy profiles are found in most instances.