This application allows for liquefaction verification using the methods of Tokimatsu and Yoshimi, Seed and Idriss, and Boulanger & Idriss 2014. For the desktop application, visit the Liquiter product page.
To verify the potential occurrence of liquefaction phenomena, procedures known in Seismic Geotechnical Engineering as “simplified methods” can be employed. These methods, applicable only to horizontal or gently sloping ground surfaces and Holocene deposits, require the evaluation of the factor of safety up to the critical depth from the ground surface:
FL(z) = (CRR M=7.5; σ’v=1atm * MSF * Kσ) / CSR
CRR M=7.5; σ’v=1atm = τult / σ’v0 is the cyclic resistance ratio, which represents the resistance normalized relative to the initial effective vertical stress (σ’v0), for an earthquake of magnitude M = 7.5 and a reference effective pressure σ’v = 1 atm.
MSF is the Magnitude Scaling Factor, which depends on the magnitude of the reference seismic action and the specific method used to estimate CRR. Kσ is the correction factor that accounts for the effective pressure at the depth where the resistance is evaluated.
CSR = τavg / σ’v0 = 0.65 * (amax,s / g) * (σv0 / σ’v0) * rd is the cyclic stress ratio, representing the average cyclic shear stress induced by the reference seismic action, normalized relative to the initial effective vertical stress (σ’v0). In this formula, amax,s is the peak ground acceleration at the surface, g is the acceleration of gravity, σv0 and σ’v0 are the total and effective vertical stresses at the considered depth, and rd is a stress reduction coefficient due to soil deformability, which can be estimated using empirical relationships associated with the different CRR (and MSF) estimation methods. The value of the average shear stress τavg = 0.65 τmax at varying depths can be more accurately determined through local seismic response analysis.