Question

JE . For steady-state seepage shown in the Figure to the right, water levels are maintained at the levels shown and water flows through the soil (shown in gray) from B to A. The cross-sectional area of the soil sample per- pendicular to flow is 2800 mm and soil permeability k is 0.05 cm/s. overflow 300 mm discharge a) What is the pressure head at point A? 280 mm 600 mm 600 mm b) What is the hydraulic gradient i in the sample from point B to A? c) Determine the volume of water which discharges in 1 min. d) If the measured discharge Q were measured at 10 cm/min, what would be the computed soil per- meability k in cm/sec?

Answer 1

. 4 300mm d 1180mm IL 280mm 600mm B -Datum Line D 600 mm (26) head Area 28comm imm? K 20.05 cm/s (PB). (a) Total head at B= Pressure head & Datum 1180 to =1180mm head loss through soil he= 300 mm Total head at A hA= ho the ha 1180-300=880mm : ha= PATZA 8802 PAT 600 Pressure head at PA 280 mm (b) hydraulic gradient ti) = he LAB 300 (LAB=J680²76000 - 600/2 GOOJZ i = 0.354

(0) volume of water discharged in a mint Q=kia = 0.05X10 X0.354 X 2800 495-6 mm2/sec 495.6X60 = 29736 mm3/min Q = 29.736 cm3/min, (d) Q = lo cm3 /min, K=? - Q= kia 10 60 - KX 0.354x2800 x10-2 K=0.017 cmis