Abstract: When soil structures are analyzed with numerical method, effective stress-based nonlinear soil models are used to predict soil deformation or liquefaction. However, model parameter calibration often becomes an obstacle to the practical applications of the model because of the uncertainties and lack of appropriate laboratory test results. In this paper, the state dependent dilatancy concept is incorporated into the existing bounding surface model, it makes soils failure conform to critical state. Based on the piezocone penetration test (CPTu) results, a procedure is proposed to calibrate a bounding surface model for simulating liquefaction and ultimate failure under monotonic or cyclic loading. The in situ residual strength is utilized as critical state obtained from laboratory tests，it is used to calibrate the parameters related to critical state line. A relationship between soil liquefaction resistance and equivalent number of cycles is developed based on published CPT-based liquefaction triggering charts, together with correlations between a magnitude scaling factor and number of equivalent cycles to liquefaction, further the procedure is introduced to calibrate unloading plastic modulus simply. Based on the profiles of piezocone penetration test, examples to illustrate the calibration procedure of the model parameters are presented finally.

Key words: piezocone penetration test, bounding surface model, state dependency, residual strength, parameter calibration