Abstract: The laws of physics and the principle of mathematics and mechanics are used as the bases for logic deduction of a numerical model for the shear parameters. They all have been proved true. In addition, soil particles are attributed to ideal particulate materials. They are within a physical phase transition space-time whose inter-particle stress fields are governed by friction. With such premise, the deduction leads to the fact that there is only one inherent parameter - normally consolidated kinetic friction angle () which represents the friction variations within a group of particulate materials. Such coupled shear stress vectors between particulate particles are all derived from time-dependent inter-particle principal stress and . The feature of logic deduction has proved that if the premises are true, then the conclusions will also be true, and vice versa. In the recent 5 years, CUC has used the above numerical model to analyze the normally consolidated Taipei sedimentary deposits. It has been proved that once the inherent parameter for each layer is explored, the proper shear behavior for that particular soil can be predicted. The results are in good agreement with those anticipated by other geotechnical professionals.