Study of Convex Corners' Effect on the Displacements Induced by Soil-Nailed Excavations

Abstract

In deep excavations, because of time, budget, and computational tools limitation, two-dimensional analyses (plane strain analyses) rather than three-dimensional ones are often used for controlling factors of safety and displacements. In most excavation projects, the excavation plan includes convex and concave corners. Unlike concave corners, the use of two-dimensional analysis for convex corners is non-conservative. In the present study, by using three-dimensional numerical modeling and comparing 3D and 2D results, the effects of convex corners on the displacements induced by soil-nailed excavations are studied for two types of soil: sand (granular soil) and clay (cohesive soil). The results of the study indicate that the length of the zone affected by the convex corner (the zone along the wall and around the convex corner where the values of the displacements are greater than the corresponding two-dimensional values) is about 0.75 to 1 times the excavation's depth. The results also show that although the horizontal soil nails are executed easier and prevent interference of nails that cross, but applying an appropriate angle over the horizon (about 10 degrees) to the soil nails can reduce the wall displacements. Furthermore, it was found that applying azimuth to the soil nails in the area affected by the convex corner, significantly increased the displacements of this area. Lastly, it has been suggested that to reduce the displacements in the zone affected by the convex corner, increasing the length of the soil nails is more effective than decreasing their horizontal spacing.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.