Study of Reinforced Concrete Retaining Wall Performance Along Erosion-Prone Slopes in Imo State

Soil erosion along steep terrain in Imo State in the South East geopolitical zone has led to widespread demand for retaining structures to protect roads, farmland, and residential areas from slope instability. This study evaluates the structural performance of reinforced concrete retaining walls constructed at selected erosion sites in Owerri, Orlu, and Okigwe zones, examining their ability to resist earth pressure, hydrostatic pressure, and surcharge loads over a five-year service period. Physical inspection of twenty retaining walls was conducted, documenting signs of forward tilt, cracking, drainage blockage, and base erosion. Structural adequacy was evaluated against design requirements for overturning stability, sliding resistance, and bearing pressure per BS 8002 and the Nigerian Erosion and Watershed Management Project technical guidelines. Results indicate that eleven of the twenty walls exhibited inadequate provision for drainage, resulting in hydrostatic pressure build-up behind the stem that contributed to forward tilting of up to three degrees from vertical. Six walls showed tension cracking at the wall-base junction, consistent with overturning moment exceedance under saturated backfill conditions. The absence of weep holes in seventy percent of walls was identified as the single most common design and construction deficiency. The study recommends a standardised retaining wall design guide incorporating drainage provisions for Imo State's high-rainfall context, mandatory inspection of weep hole functionality after each major rainfall event, and post-construction monitoring for all walls on slopes exceeding 20 degrees. Keywords: retaining walls, erosion control, Imo State, drainage, slope stability.