Bearing Capacity and Settlement of an Isolated Ring Footing on Sand Reinforced with Geogrid

摘要

The ultimate bearing capacity and settlement of an isolated ring footing on reinforced sand is numerically investigated in this paper. The code, FLAC~(3D) Lagrangian Analysis of continua), based on finite difference method is used in the numerical simulations. The numerical modeling performed using the elastic-perfectly plastic Mohr-Coulomb failure criterion based on non-associated flow rule. To assure the reliability of numerical results, a verification study was conducted on the prior experimental studies on footing resting on reinforced sand. Thereafter, the comparison between numerically obtained and existing experimental results showed an appropriate conformation. Finally, an attempt was carried out to acquire the optimum size and orientation of reinforcement layer(s) (i.e. diameter of reinforcement, embedment depth of first reinforcement layer, vertical spacing between reinforcement layers) which makes the ultimate bearing capacity maximum and the settlement minimum. Results showed that using sufficient geogrid layer(s) at appropriate places led to an increase in the ultimate bearing capacity of ring footings on reinforced sand about 30-70% and decrease in the settlement about 25—40% regarding the number of reinforcement layers. In addition the optimum geometrical parameters of geogrid layers are presented in the paper.