An Investigation on the Effect of Intermediate Principal Stress on the Solution of Bearing Capacity Problems by the Method of Stress Characteristics

This paper aims to investigate the effect of assuming different values of intermediate principal stress σ2, in the solutions obtained for stability problems in soil engineering. The bearing capacity of strip and circular footings has been selected for this purpose which represent typical plane strain and axisymmetric stability problems. Investigations has been made using the method of stress characteristics as usual; but with yield criteria other than Tresca and Mohr–Coulomb that allow variation in σ2. Variation in σ2 has been considered in the form of usual parameter b which is the ratio of differences of principal stresses. At the outset; the parameter b is set to match these criteria with Tresca or Mohr–Coulomb. This is based on usual assumptions of associativity in plane strain, and Haar–von Karman flow-regime in axial symmetry. The value of b has then been changed from these values to see how the solution is affected by variation in σ2. Results indicate that the usual solutions are not generally on the safe side; and if the material behavior is really different from our assumptions, this should be considered in calculations.