The effect of cutoff angle on the head pressure underneath dams constructed on soils having rectangular void

Abstract In this research, a hydraulic model is used to find the effect of cutoff angle and dimensions void in soil on head pressure leakage under dam, finding best size will have positive effect. The was designed with that can be moved three angles (45°, 90° 135°) center dam ratios (width ( W )/the width b ) = 0, 0.34 0.69) were taken. Head measured using piezometer installed front model. When flow reached balance, measured. From results, it observed lowest value occurs when ratio 0.69. principles dimensional analysis non-linear regression by IBM SPSS 19 an empirical formula for computation depending void.