FLAC

UBCTOT: Typically, Rayleigh damping of 4-8% is used with UBCTOT Naesgaard 2011 p54

UBCSAND: KeG = 21.7∙ A· ((N1)60)0.33 where A = 15 to 20 KeB = bulk modulus number = alpha· KeG where alpha· = function of Poisson’s ratio and ranges from 0.67 to 1.33 Naesgaard 2011 p56

Phase transformation friction angle (φpt) = 40.0 – ((N1)60) · 0.65) ≤ 33º Peak friction angle (φf) = 33 + (((N1)60) / 10)1.65 Naesgaard 2011 p56 UBCSAND is, typically, run using a fluid modulus that is about one quarter that of the actual fully saturated fluid modulus

In addition to the hysteretic damping, a nominal amount of Rayleigh viscous damping equal to 0.5% of critical was assigned using a center frequency of 1.0 Hz. Version 904aR manual

UBCHYST: A small viscous (Rayleigh) damping component (fraction of critical damping of 0.5% to 1%) is used to give numerical stability at small strains Naesgaard 2011 p66