Correct Answer - Option 1 : 0.94
Concept:
Critical hydraulic gradient (ic):
- The quick condition occurs at a critical upward hydraulic gradient ic, when the seepage force just balances the buoyant weight of an element of soil.
- The critical hydraulic gradient is typically around 1.0 for many soils.
- At the critical conditions, the effective stress is equal to zero.
Critical hydraulic gradient,
∴ \({{\rm{i}}_{\rm{c}}} = \frac{{{\rm{G}} - 1}}{{1 + e}} \)
Calculation:
Given,
G = 2.67
e = 0.78
Critical hydraulic gradient, \({{\rm{i}}_{\rm{c}}} = \frac{{{\rm{2.67}} - 1}}{{1 + 0.78}} = 0.94\)