Determining ultimate bearing capacity of shallow foundations using a genetic programming system

Three genetic programming models are developed for determining the ultimate bearing capacity of shallow foundations. The proposed genetic programming system (GPS), which comprises genetic programming (GP), weighted genetic programming (WGP), and soft-computing polynomials (SCP), simultaneously provides accurate prediction and visible formulas. Some improvements are achieved for GP and WGP. The SCP is also designed to model the ultimate bearing capacity of shallow foundations with polynomials. Laboratory experimental tests of shallow foundations on cohesionless soils are used with parameters of the angle of shearing resistance, the unit weight of the soil, and the geometry of a foundation considers depth, width, and length to determine the ultimate bearing capacity. Analytical results confirm that all GPS models perform well with acceptable prediction accuracy. Visible formulas of GPS models also facilitate parameter studies, sensitivity analysis, and application of pruning techniques. Notably, SCP gives concise representations for the ultimate bearing capacity and identifies the significant parameters. Although shear resistance angles have the largest impact on ultimate bearing capacity, foundation width and depth are also significant.