Impact of inclined double-cutoff walls under hydraulic structures on uplift forces, seepage discharge and exit hydraulic gradient

In hydraulic structures design, using cutoff walls is essential to reduce and control the resultant uplift force (U), seepage discharge (Q), and exit hydraulic gradient (i). This research investigates the effectiveness of inclined double cutoff walls under hydraulic structures, considering the influence of depths, locations, and inclination angles of the upstream and downstream cutoff walls by using Finite Element Method (FEM). The results confirmed that installing a deeper cutoff wall on the downstream reduces the exit gradient even further. In the case of the cutoff walls located in the upstream and downstream ends, the exit gradient will be less than when the cutoff walls are installed at a closer distance. Increasing the inclination angle of downstream cutoff wall has a major impact on exit gradient reduction. Embedment of cutoff walls in the upstream and downstream ends with right angles and equal depths reduces the seepage discharge more than other cases.