A 40° slope is excavated to a depth of 10 m in a deep layer of saturated clay of unit weight 20 kN.m3; the relevant shear strength parameters are cu = 70 kN/m2 and φu = 0. The rock ledge is at a great depth. The Taylor's stability coefficient for φu = 0 and 40° slope angle is 0.18. The factor of safety of the slope is :

• 2.0
• 2.1
• 2.2
• 2.3