Ultimate Pullout Capacity of Vertical Anchors in Frictional Soils

Abstract

This paper presents an analytical model for the estimation of the ultimate pullout capacity of vertical anchors embedded in frictional soils. The analytical model developed using the principle of limit equilibrium will be capable of capturing more realistic variations in pullout capacity because of its inherent capability to consider three-dimensional failure scenarios, anchor roughness, and anchor material effects. The analytical model was verified with three-dimensional numerical simulations. In addition, the predictions from the proposed model were compared to several pullout capacity prediction models using 86 experimental data points from literature. Results show that the present model can predict the pullout capacity of shallow and intermediate anchors with more accuracy and reliability than the available pullout capacity prediction models. In addition, a comprehensive parametric analysis is also presented. Some of the basic conclusions are: the demarcation aspect ratio between a single and continuous anchor is 10 rather than 5; the omission of the contribution from side flanks to the ultimate pullout capacity resulted in a discrepancy of as much as 37.4%; and δ/φ′ does not remain constant, irrespective of the embedment depth ratio and anchor aspect ratio.