Parameters of constitutive models are generally obtained by comparing results of numerical forward simulations with measurement data. Often the parameter values are varied by trial-and error in order to reach an improved fi t and to obtain plausible results. However, the description of complex soil behavior requires advanced constitutive models (e.g. [9]). The rising complexity of these models mainly increases the number of unknown constitutive parameters. Thus an effi cient “by hand” identification becomes quite difficult for most practical problems.