Predicting Road Failure Susceptibility through Integrated Geologic, Geomorphologic, and Geotechnical Analysis: A Case Study from Southeastern Nigeria

Inadequate engineering geological site investigations are major cause of road failure due to a lack of complete information for project design. Considering the cost of conducting site investigations and the need for the economical use of project funds, intensive sampling spacing is often sacrificed in favour of intuitive assumptions, leading to an increase in the error margin. For this reason, it became imperative to assess an alternative engineering geological site investigation method that provides contiguous data over a large area at low cost. To this end, digital elevation model (DEM) – a remotely sensed data was integrated with geological field investigations and geotechnical laboratory tests to ascertain the geotechnical properties of the underlying geologic materials in areas obscured by the built environment. The derived geologic, geotechnical, and DEM data were integrated and geospatially distributed within the study area using geostatistical methods. This resulted in geomorphologic and lithostratigraphic maps, which revealed the spatial distributions of the slope and geologic materials, respectively. The distribution of the road failure events (RFEs) on the geomorphologic and lithologic map revealed that flat areas underlain by argillaceous materials are more susceptible to road failure than steep areas underlain by arenaceous materials. Boundaries between argillaceous and arenaceous materials are also susceptible to road failure because of the hydraulic conditions of the area. The high predictability of RFEs following this method was evidence that it could serve as an alternative low-cost method for engineering geological site investigations.