Toughness index is defined as the ratio of

The hydraulic head that would produce a quick condition in a sand stratum of thickness 1.5 m, specific gravity 2.67 and voids ratio 0.67 is equal to

Clay layer A with single drainage and coefficient of consolidation Cv takes 6 months to achieve 50% consolidation. The time taken by clay layer B of the same thickness with double drainage and coefficient of consolidation $$\frac{{{\text{Cv}}}}{2}$$ to achieve the same degree of consolidation is

Degree of consolidation is

Select the correct range of density index, 1_D