Bearing capacity of tapered piles in clay under undrained condition

Based on the lower bound limit analysis, the bearing capacity of a tapered pile in clay is computed. The numerical analysis is performed for various parameters such as embedment length to base diameter ratio (L-p/D-0), taper angle (beta), a factor m for the linear variation of cohesion, and adhesion factors (ab and as). The results are presented in the form of bearing capacity factors N-ct(b), N-ct(s) and N-ct which represent resistances due to pile base, shaft and total load carrying capacity, respectively. The factor N-ct(b) is found to be decreasing, while the factors N-ct(s) and N-ct are increasing, due to an increase in beta. The increases in Ncts and Nct are found to be significant for smaller beta (between 1-3 degrees) and larger L-p/ D-0. The bearing capacity factors are significantly affected by undrained cohesion. It is expected that the results of the present analysis will be helpful to the practicing engineers.