Abstract:
Every year, many bridges are collapsed due to natural and human factors which
results in tremendous effects on the economic growth especially in developing
countries. As among the principal causes of bridge failures, the bridge abutment
failure has the potential to cause substantial damage to the bridge and it is affecting
the whole system of the road. This study were aimed to investigate the causes of
bridge abutment failure on gravel road and to provide the remedial measures on their
failures. The study was covered the bridge constructed on gravel road in West Shawa
Zone from 2002 to 2012 that facing defects. The study applied a descriptive and
exploratory research design and Purposive sampling techniques. From total
population bridges, six (6) collupsed bridges were selected purposively. To examine
the causes of abutment failure, critical review of relevant literature, laboratory test
and site inspection through design review and as-built data was checked. Geological
data obtained from the laboratory tests were analyzed by using GeoSlope 9.1.
software. This softeware was used to analyze different geotechnical computations like
slid and slope stability analysis. ArcGIS and ArcSWAT software were used in
delineting rivers catchment area and in determining abutment scouring. The results
of the study were found scour depth problem, river bank instability and abutment
foundation slid, and design error which results from insufficient data for design,
unsuitable materials and construction defect.Their effects were results in overturing,
crack and collupes of the abutments. The remedial measures are construction
materials’ quality and the on going costruction process of bridge should be strictly
supervised and controlled, All geotechnical properties and other factors should be
investigated before designing bridges inorder to alleviate scour depth, slope
instability, under estimation of stream flow depth and narrowing river way
problems
