A retaining wall with a smooth vertical back retains sand backfill for a depth of 6 m, The back fill is horizontal and the soil retained has the following properties. = 30 e = 0.74 and 6=2.68 of For the same problem, the back fill is having a surcharge 9 = 20 kN/m? Determine the magnitude and the ^"application of the resultant thrust due to active earth pressure on the retaining wall.