Evaluation of an instability for a full-scale model slope under multi-step excavation based on the monitoring of 2-dimensional displacements

Abstract

Monitoring of 2-dimensional displacements at 6 points on the surface of full-scale model slope under multi-step excavation was conducted and monitored data was analyzed to establish the method to evaluate an instability of the slope under excavation. 2-dimensional displacements mean the displacement parallel to the surface of the slope and the displacement perpendicular to the surface. Direction of synthetic displacement which is a root of the sum of square of each displacement was derived from the monitored data. It approached to almost constant value as the displacement parallel to the surface increased at upper part of the slope where creep deformation after the excavation leaded to the failure while it did not converge to constant value at lower part where the slope collapsed during excavation. Direction of synthetic displacement at large displacement means the direction of slip surface. Direction of synthetic displacement can be an indicators of the instability of the slope under excavation in the case that slope collapses after creep deformation.