Seite - 1201 - in Book of Full Papers - Symposium Hydro Engineering

and the average absolute percentage difference (AAPD) is about 8.8%. For downstream slope, (AME) is about 0.075 and (AAPD) is about 4.1% which are all within the acceptable accuracy. Table (1): Minimum calculation results of factor of safety F.S downstream slope F.S upstream slope Methods of calculation Steady state End of construction End of construction Rapid drawdown 1.90 1.911 2.25 1.618 Present study GeoStudio software (Bishop's) 1.80 1.86 2.03 1.515 Referance [21] Analatical solution (Bishop's) 5.56% 2.47% 10.83% 6.79% Absolute percent difference 7. Application of Geostudio on Mandali Dam Mandali dam is an earth fill dam which is located on Harran Wadi, in the governorate of Diyala which is extends to the northeast of Baghdad, Iraq (Fig.5). The dam has been designed by Directorate General of Dam and Reservoirs, Iraq. The Wadi bed is gravely and permeable to some depths as it is clear from the geological investigations Mandali dam has a central core and the dam total length is about 1316 m. The maximum height of the dam is about 14m [Ministry of water Resources, Iraq] [22]. Figure (6) shows the dam cross-section, while Table (2) gives the material properties of the dam components. The dam geometrical properties can be seen in Table (3). Table (2): Material properties of Mandali dam, Iraq [22, 23]. Layer (soil type) Physical and mechanical properties Shell (Sandy soil) Clay core (Very stiff clay) Foundation (Stiff clay) Filter (Sandy gravel soil) Bulk density (γ) [KPa] 21 19.2 22 21 Angle of internal friction (ϕ) [degree] 40 15 30 37 Cohesion (c) [KPa] 0.0 40 5 0.0 Permeability (k) [m/sec] 1.37*10−5 9.88*10−9 10−8 10−2 Poisonʹs ratio (ν) 0.3 0.36 0.32 0.4 The elastic Modulus (E) [KPa] 35000 19000 100000 30000 7.1 Safety Criteria of Mandali Dam The Geometric properties of Mandali dam were checked using BDS (1994) [19]. Table (3) gives the results of the comparison. It can be noticed that the geometric design of the dam is acceptable based on the recommendations of The British Dam Society (1994) [19]. Table (3): Comparison between original section of Mandali dam and (BDS) safety limits Parameter Mandali Dam (BDS) Safety limits Safety of dam status Crest width 8.0 m Not less than 2.0 m Acceptable Upstream slope 2.7:1 2.5:1 Acceptable Downstream slope 2.4:1 2:1 Acceptable Free board 1.50 m Min. free board = 1.50 m at Max. Fitch = 4 km. Acceptable (Maximum head over spillway = 2.5 m) Bed width of core 58 m Not less than 𝐻 3 = (4.67 m) Acceptable Core slope 1:1.77 1:12 Acceptable 1201