An excavations to be made up to a depth of 6 m in cohesive soil having a unit weight of 20 kN/m3 what is the required cohesive strength of clay to keep the sides of the earth remains vertical without any support.
1
29.3 kN/m2
2
28.9 kN/m2
3
30.0 kN/m2
4
31.0 kN/m2