Jornal de Geologia e Geofísica
Acesso livre
ISSN: 2381-8719
ISSN: 2381-8719
Hika Negeri Feyisa*, Fekadu Tamiru Gebissa
Road failure is widely known in developing countries that cause the loss of many resources due to lack of scientific studies before the construction starts. Thick clay soils, fractures and shallow groundwater are the inducing factors for the failed road segment. Two-dimensional electrical resistivity imaging and magnetic methods were used to map the subsurface lithology and subsurface geological structures that cause Gedo-Ijaji asphalt road failure in Chelia Zone, Oromia, western Ethiopia, in order to solve such serious problems. The lithological units of each geoelectric layer within the study area was studied and interpreted using six profile electrical resistivity imaging and six magnetic profiles with a total data points of 123 collected along the two sides of the asphalt roads and perpendicular to the asphalt road. The electrical resistivity tomography data were processed and inverted using RES2DINV computer software, while the magnetic data were processed using OASIS MONTAJ software. The result of electrical resistivity imaging displayed that the study area is composed of subsurface geo-electric layers with a resistivity between 1 Ωm to 37 Ωm. The depth of investigations by electrical resistivity imaging is averagely 39 m. The result of the study indicated expansive clay formation of 4 to 12 meter thick overlying the weathered basalt. The thickness of these expansive soil was constrained to nearby borehole data and tomography showed nearly horizontal layer. While magnetic results indicates weak zones/altered zones and high anomaly trending from NW-SE. The study area is highly characterized by clay materials on the top layers and affected by shallow geological structures. Analytic Signal solution techniques on the analytical signal data were applied to identify a magnetic anomalous body. Therefore very shallow investigation might not be advisable for highway engineering structures.