Application of the Failure State in Undrained Simple Shear to the Shaft Capacity of Driven Piles

摘要

An attempt was made to fit data obtained from undrained simple shear tests into a consistent framework. It has long been realized that strengths measured in simple shear are generally lower than corresponding strengths measured in triaxial compression. A rationale for this difference has been proposed, based on two widely accepted hypotheses: that, at failure, the ratio of major and minor principal stresses approaches a limiting ratio which is largely independent of the value of the intermediate principal stress; and that soil at a particular water content will approach a particular value of mean effective stress as it is sheared to failure, regardless of the exact mode of shearing. In addition, an assumption has been made concerning the directions of potential rupture planes as failure in the soil is initiated. These three assumptions lead to quantitative estimates of the ratio at failure and of the ratio measured in triaxial compression. Comparison of the predictions with experimental data from nine different clays shows reasonable agreement.