Influences of Construction Methods and Working Mechanisms on Stress Distribution in Deep Foundation Design

Abstract

In foundation design, stress distribution is crucial for determination of bearing capacity and settlement. Stresses are generally calculated using elastic models proposed by Boussinesq and Mindlin which mainly consider foundation size and depth. In fact, stresses are also dependent on construction methods and mechanisms of stress distributions, but these factors are rarely considered in engineering design. This paper used the FEM to simulate the construction method and analyzed stress distributions in diaphragm wall and open caisson foundation. The study showed that the additional stress under a caisson foundation is always greater than that beneath a diaphragm wall foundation, thus showing the importance of the effect of construction method on stress distribution. It was also found that Mindlin's solution is more appropriate than Boussinesq's solution for calculation of total settlement of deep foundation even though the latter may provide better stresses near the bottom of the foundations. In addition, the settlement obtained using Mindlin's approach is between the settlement of caisson foundation and diaphragm wall foundation, and the discrepancy goes up with an increase in foundation depth.