In the case of construction of port facilities on the soft ground, some foundation improvement is needed and the improvement cost accounts for fairly great part of the total construction cost. We have ever decided the economic sectional from form experiences or trials, but its design work is fairly intricate even for skilled engineers. Such being the case, we have developed a computer program for the purpose of saving time and labor.
　In this paper, SUMT (Sequential Unconstrained Minimization Technique) which is one of the non-L.P optimizing techniques is applied to decision on the sectional form. In formularization we add some modificaitons to SUMT and the safety factor calculated on circular failure surface is approximated with Spline Function to reduce calculating time.