Prediction of Quantitative Response of Under-Reamed Anchor Piles in Soft Clay Using Laboratory Model Study

Abstract

Abstract The foundation of many civil engineering structures is required to be designed as an anchor foundation subjected to upward load action. The shallow as well as deep anchor in soft clay is an important but complex soil-foundation system that must be analyzed theoretically. As direct determination of the quantitative response by the field test is a very difficult and expensive exercise, the physical modelling technique is considered as an easy alternative for prediction of (i) ultimate pulling capacity and (ii) pull-rise curve. This paper highlighted the potential use of two parameters viz. (i) factor of geometrical relationship (K) and (ii) cohesion factor (N), obtained by conducting laboratory tests on two models of different scale factors for the intended purpose. The K and N parameters were constant for both the prototype foundation and small size model tested in laboratory. The under-reamed concrete pile in soft clay was considered as a soil-foundation system and shallow as well as deep under-reamed anchor piles were investigated in this study. Besides, straight shafted concrete piles were also considered in both categories of shallow and deep anchors. It was found that the physical modelling technique using two characteristic system parameters and by incorporating the model scale factor effect enables the prediction of the earlier stated quantitative response of prototype under-reamed anchor pile foundation in soft clay with a reasonable degree of accuracy. A methodology involving curve fitting procedure was also developed to predict the “pull-rise” curve for a prototype soil-foundation system under consideration.