Sustainable rural infrastructure: guidelines for roadside slope excavation

Abstract

The construction of non-engineered, equipment-based rural roads in Nepal Himalaya is one of the predominant causes of landslides. The construction frequency of such roads has significantly increased over the past decade. However, the present guidelines governing slope excavation for these roads are not based on geotechnical characterizations of sites. The current study uses the limit equilibrium method with the Mohr–Coulomb constitutive model to determine safe cut heights and slopes for varying geometric and material parameters. GeoStudio Slope/W was used to model soil slopes with various gradients, and cuts with varying depths and slope angles were modeled to calculate the factor of safety (FoS) against shear failure for different geometric and material conditions. The results of the study were visualized in design charts with FoS as the dependent variable. The analysis highlights the importance of different parameters, i.e., excavation depth, excavation slope, and existing ground slope in the FoS, in addition to the slope-forming material. Furthermore, a field study was carried out to validate the model using the clustering approach. The results from the field are similar to those from the numerical model, although some additional site-specific parameters like vegetation cover and surface runoff conditions should be considered before selecting the cut slope. Finally, this study proposes that future road construction guidelines should consider terrain parameters, hydrology, and geotechnical site conditions to promote sustainable road infrastructure and reduce future disaster risks in the Himalayan region.