Large-scale model tests on performance of assembled multi-step cantilever retaining walls pulled locally with geogrids

Abstract

Assembled multi-step cantilever retaining walls pulled locally with geogrids is a novel structure with light weight, quick installation, and good applicability for high fill earthworks. In order to support the practical design and construction in a highway embankment project, four scaled model tests with similarity ratio 1:5 were carried out to obtain the performance of four-step cantilever walls with different layouts of geogrids under the strip surcharges on the top surface of the retained embankment. The test results show that the wall displacement takes on a unimodal profile with obvious bulge on the middle two steps, and lateral movement of the whole wall can be effectively limited by geogrids on the middle two steps. The lateral earth pressure on the wall obtained by numerical simulation via FLAC3D is consistent with the measured one in terms of magnitude and variation tendency. However, the calculated earth pressure based on the current design methods in some specifications results in an obvious overestimation. Compared with unreinforced four-step cantilever walls, the maximum lateral earth pressure on the wall and embankment settlement are reduced respectively by up to 62 % and 60 % owing to the existence of geogrids on the upper three steps. The critical slip surface of the wall-slope system exhibits approximately a three-section composite slip surface composed of circular arc surface in the backfill, plane along the bottom of the lowest wall, and Rankine passive slip surface in front of the wall, which accordingly allows a combined horizontal and oblique slice analysis method of overall stability to be put forward.