New Calculating Approach for the Ultimate Bearing Capacity of a Shallow Foundation

Abstract

The conventional method for calculating the bearing capacity is the method derived by Terzaghi, in which the embedment is simulated as a surface surcharge. The total bearing capacity is determined with two different failure mechanisms using the superposition method. Although a large number of solutions of the bearing capacity coefficient Nγ have been presented by different authors, no exactly defined failure mechanism for estimating Nγ is available. A new approach was developed in this study without a simulated embedment as a surface surcharge that utilizes two methods, the individual minimum (IM) and global minimum (GM), based on the limit equilibrium method to estimate the bearing capacity. The failure mechanisms for determining the bearing capacity, the critical failure mechanisms for the resistance forces due to cohesion and soil weight, respectively, were defined with two angles α and β. The results of the IM method with superposition method were acceptable when compared with those obtained using the German Standard DIN 4017; the greatest difference between the results obtained with these two methods was approximately 8%. Using the GM method, the total bearing capacity was estimated with the well-defined influential single failure mechanism, and the results were compared with the results of the finite-element analysis. The influential failure mechanisms were comparable with each other, and the results of bearing capacities using finite elements were overestimated. The new approach could be suitable for practical applications.