Abstract:
Rock anchors and horizontal drains provide cost effective solutions for large slope failures. This case history presents how a design and construction team prevailed on a site where a prior repair effort had failed to perform. Site grading during construction of this community in 2006 steepened a natural slope. Over time the fill began to slide downslope, damaging the backyards of several homeowners along the crest of this slope. A rock buttress stabilization system was designed and installed but failed to perform adequately. This presentation shows how a properly designed and constructed system of rock anchors and drains were used to arrest the unstable rock buttress during the winter of 2021/22. A total of 37 rock anchors were installed and tested to a 240k working load along with 11 horizontal drains. This site continued to pose challenges to the design team during construction until the last anchor was installed and successfully tested. This case history illustrates how a design and construction team had to roll with the geotechnical punches to achieve success on a difficult project.