Assessing the effectiveness of toe buttressing on slope stability through monitoring and numerical modelling in a quarry in Germany

Slope instability poses significant challenges in geotechnical engineering, necessitating effective mitigation strategies. Among these strategies, toe buttressing has emerged as a prominent method, involving the strategic placement of materials at the base of unstable slopes. However, the efficacy of toe buttressing remains insufficiently explored in scientific literature, particularly through the integration of real-time monitoring and numerical modeling. This paper explores the effectiveness of toe buttressing as mitigation measure for slope stability without the influence of additional stabilization methods. Through a combination of field monitoring, laboratory testing, and the finite element analysis, we assess the influence of toe buttressing on slope dynamics and stability under varying environmental conditions. The study site, located in a basalt quarry in Nentershausen, Germany, experienced a landslide, with the sliding plane located at the interface between basalt formations and the underlying clay layers. Our monitoring results demonstrate that the placement of a 10 m thick toe buttress effectively halted the movement of a 295,000 m³ landslide. Additionally, we investigated the impact of different buttress configurations and groundwater levels on the factor of safety (FoS) using a 2D finite element model. The results clearly show the important role that toe buttresses play in strengthening slope stability. Our study emphasizes the need for more detailed case studies focusing solely on toe buttressing as a means of stabilization. Such research is essential to develop statistical models that can determine the necessary buttress volume and height to support/stabilize different landslide scenarios. Additionally, we discuss the broader implications of our study and future research for slope management applications and underscore the need for interdisciplinary approaches to address the complexities of slope stability in a changing environment.