Effect of Using Vertical Drainage Column in Hemrin Dam on Factor of Safety Under Seismic Load

Abstract

Recent years have seen an increase in the use of computer-based numerical models to test the stability of earth dams and to simulate the impact of all the factors that affect their safety. Geo-Studio software and its sub-programs SLOPE/W, and QUAKE/W are used to determine the factors of safety and stability of dams, and investigations of dynamic analysis, a finite element serves as its base to do the numerical modeling for this study. The Hemrin Dam represents the case study and is regarded as the study's major focus. The results showed that the values of the safety factor increased from (1.439) to (1.583) when the water level is 8m, from (1.365) to (1.549) when the water level is 16 m, and from (1.084) to (1.317) maximum water level is 32m, without and with a vertical drainage column, because the pore water pressure is reduced and the effective stress is increased. In the case of a Rapid drawdown of water when a vertical drainage column is added, the value of the factor of safety decreases from 1.371 to 1.306 for the initial time, while decreasing from 1.406 to 1.363 for the second day of rapid drawdown. These reductions result from there is a delay between the process of the reservoirs' water level dropping and the water level lowering on the earthen dam's side. The vertical drainage column is crucial for the stability of the dam as the water is drained using the existing vertical and horizontal filters which eventually improve and increase the value of the effective stress.