2021 Volume 77 Issue 1 Pages 44-59
The earth retaining is often designed using beam spring model assuming the retaining wall is a beam element, the strut is an elastic spring element, and the ground is a spring. A coefficient of horizontal subgrade reaction on the excavation side is set to a constant value, which is obtained from the in-situ test. At the excavation site where the soft alluvial cohesive soil was thickly deposited, it was confirmed by back analysis based on the measured values that the horizontal subgrade ground reaction becomes smaller as the displacement of the earth retaining wall increases. This method does not clarify any specific mechanism in stress-deformation in the braced excavation.
In this paper, the dependence of horizontal subgrade reaction on the displacement of the earth retaining wall was analyzed from the field measurement data and the in-situ test data. It was found that the wall displacement can be appropriately predicted by reducing the initial horizontal subgrade reaction to 30% near the bottom of the excavation. The results emphasize the dependence of the horizontal subgrade reaction on the wall displacement. Also, the behavior of the ground was simulated by the elastoplastic FEM analysis. It was seen that a tendency of an expansion near the bottom of the excavation and a compression tendency at a depth further from the bottom of the excavation could be reproduced with the elastoplastic FEM analysis. The dependence of the horizontal subgrade reaction on the displacement of the retaining wall due to the excavation is minimal.
