Stochastic Analysis of Liquefaction Under Earthquake Loading

Abstract

Liquefaction of sand deposits during earthquakes is studied as a problem of
\nrandom vibration of nonlinear-hysteretic systems. The random vibration results
\nlead to the determination of the mean and standard deviation of the strong-motion
\nduration of a random seismic loading with a given intensity that causes liquefaction.
\nThese statistics are used to define the seismic resistance curves against liquefaction
\nin the deposit. It is assumed that liquefaction occurs when the excess pore
\npressure becomes equal to initial effective overburden pressure, i.e., when the
\nshearing stiffness of the sand deteriorates to zero under repeated alternate shaking.
\nThe random vibration results, together with the results from the uncertainty
\nanalysis of the soil properties, are also used to calculate the reliability of sand
\ndeposits against liquefaction under a random seismic loading with given intensity
\nand duration. These conditional reliabilities, and the probabilities of all
\nsignificant seismic loadings for the site over a specified time period, are then
\ncombined to obtain the lifetime reliability against liquefaction.