PLAXIS LIQUEFACTION MODEL UBC3D-PLM - Knowledge Base

• ne is the elastic shear modulus index and has a default value of 0.5;• np is the plastic shear modulus index and has a default value of 0.5;• R f is the failure ratio n f /n ult like in Duncan-Chang mode (0.9);• P A is the atmospheric pressure;• fac hard is the densification factor. It is a multiplier that controls thescaling of the plastic shear modulus during secondary loading. Above1 the K p Gbecomes higher and the behaviour stiffer and bellow 1 theK p Gbecomes lower and the behaviour softer;• N1 60 is the corrected SPT value of the soil. If this is not known anapproximation with relative density can be made as shown in Equation1.36;• fac post is a factor can be used to soft the behaviour of the soil duringthe post liquefaction behaviour. It is not recommended to use it inboundary value problems but only in element tests. If is not used avalue of 1 or 0 can be entered;K e BK e G= 2(1 + ν′ )3(1 − 2ν ′ )(1.35)N1 60 ≈ RD215 2 (1.36)P P R = p′ i − p′ cp i(1.37)where p ′ i is the initial effective mean stress and p′ c is the current effectivemean stress.When P P R equals 1 then the soil is in a liquefied state.The PPR state variable can show the current status during the calculation18