Vertical Bearing Capacity of Foundations with Large Embedment Depth in Normally Consolidated Clay

Foundation bearing capacity has been well studied in homogeneous soil under a condition of embedment depth within five times the foundation effective characteristic length. However, the penetration depth of deep-sea anchoring foundations can be far more than five times the effective characteristic length. This study aims to investigate the vertical bearing capacity of the strip, circular, and conical foundations within a large embedment depth range in normally consolidated clay. Parametric studies were conducted to analyze the effect of soil nonhomogeneity and foundation–soil interface roughness with the aid of the finite-element method combined with a developed subroutine. Results show that no critical value was found for the vertical bearing capacity even at a large embedment depth. The embedment depth also influences the relationship between the soil nonhomogeneity and the foundation bearing capacity factor, Nc. Friction coefficient has a great influence on Nc of the conical foundation. Comprehensive formulas for calculating Nc of the three common foundations are proposed based on parametric studies. The simple formulas will provide a reference for geotechnical engineers.