Case Study of Slope Failures in Canal

An irrigation project included a well-distributed network of canals. The trapezoidal section of the main canal made a deep cut through lateritic soil and faced several major and minor slope failures during its construction. The failures, in general, were of two types: (1) retaining wall failure, and (2) surficial slope failure. The laboratory and mineralogical studies identified the dispersive nature of the lateritic soil as the primary cause of the slope failures. The results of stability analysis performed in GEO5 showed that internal and surficial erosion occurring in dispersive lateritic soil aggravated the slope failures. The high-pore pressure development during heavy rainfalls and excessive erosion of the soil from the canal slope pushed the retaining wall into the canal, thereby hindering the irrigation project. The soft and nearly saturated clayey foundation soil at these locations contributed to this sliding failure due to the loss of friction between the soil beneath and the retaining wall.