The piezocone penetrometer intrudes into the ground with the speed of 2 cm/sec. During penetration, the drainage condition is a partially drained condition. Therefore, the excess pore pressure during the piezocone penetration is a function of the permeability of soils as well as the stress-strain parameters. Thus, one may extract the permeability information from the measured penetration pore pressure by applying a proper coupled theory of mixtures. Based on the coupled theory mixtures, Elsworth (1993), Song et al. (1999), Voyiadjis and Song (2000) reported the "on-the-fly" method for the permeability estimation from the penetration pore pressure responses. These methods, however, are based on the sophisticated constitutive relationships and time consuming, and many times, the practicing engineers do not have enough background to fully utilize the technique. Researches to improve computation time are under progress.