Assessment of Predictive Equations of Extents of Failure Zone in Sand Beneath the Cutting Edge of Open Caisson Using Image Analysis

Open caissons are classified as deep foundations. Caissons are sunk into the ground by removal of soil within the caisson shaft. A cutting edge with a tapered inner face is provided at the bottom of the caisson to allow the bearing failure of the soil. The bearing failure of soil results in the formation of influence zone which is termed as failure zone. In this study, the 1g caisson model tests on sand are carried out with different configurations of cutting edge, i.e., varying radii ratio and different cutting angles and different sinking depths to evaluate the radial and vertical extents of failure zone. In the tests, the half-cut caisson models are penetrated in the sand and series of photos are captured. Using the captured photos, image analysis is performed to obtain the experimental failure zone. Based on the literature, the predictive equations to determine the extents of failure zone are assessed by comparing the extents of failure zone obtained from the experiments and the equations. The predictive equations help in quick estimation of the extent of failure zone based on the configuration of the open caisson adopted at the construction site.