Question

Problem 3: A constant-head permeability test was performed on the soil sample shown below. The hydraulic conductivities were 0.04 cm/s for the sand and 0.0004 cm/s for the silt. The cross-sectional area of the sample is 10 cm², of which 9 cm' is sand and the remainder is silt. (a) Plot how the total hydraulic head (expressed in terms of AH) and hydraulic gradient vary along the length of the sample. (b) What would be the hydraulic conductivity (k) for a homogenous soil sample that produced the same flow rate as obtained with this layered sample? Is this equivalent homogenous k closer to that of the sand or of the silt? y 10cm Toh 9 SAND, K, SILT, K2

Answer 1

@ • Hydraulice head (94) dees net depends on length le of the sample, so DH will be constant ala DH1 Era i is • Hydraulic gradbent, ta on it show inversely proportional to length 'l , DHT - a> B Key = hydraube Conductivity for longitucional flow Ik H + Katt KsH₂ = 0018[:46] + 8.00 m2 to 3 Ha 4 volsed [tota 6.03 604 ans illene Key is close to J K of sand.