EVALUATION AND ANALYSIS OF STABILITY OF CANAL BANKS IN WEAK SOIL-A CASE STUDY

Abstract

The effect of flowing water or seepage water and continuous rainfall of high intensity are generally, recognized as important factors in stability of side slopes of canal banks. However, effects of these factors on stability of slopes have not been properly identified. Seepage occurring within a soil mass causes seepage forces, which have much greater effect on stability than is commonly realized. The presence of pore water pressure causes reduction in shearing resistance of the soil. Erosion of side slope of canal banks in deep cutting, either by flowing water in canal or by intense rainfall may cause of removal of certain weight of soil which would be, deposited in the canal section due to sliding and thus causes decrease in water way of canal. Erosion leads to weakening the banks of canal in heavy filling reaches. The Samrat Ashok Sagar Project (SAS) and Tawa Project (both in Madhya Pradesh) were constructed during the period 1973-76 and 1972-76 respectively. In SAS project, right bank canal at RD 4.92 and 12.36 km in a length of 360 m each and its distributary at . RD 2.88 km in a length of 900 m, passes through high level ground. The soil strata is yellow soil 2 to 3 m thick, over lain by black cotton soil at top. The maximum depth of cutting at these locations are 6.03 to 8.58 m which is 4.95 to 10.2 times the full supply depth in canals. These channels were constructed in 1 981 -82 adopting normal design criteria i.e. side slope of 1.5 H to 1V, with provision of berms at every 3 m depth and non scouring velocity of flow in channels...