George is analyzing a silty sand. It has a void ration in loosest condition equal to 0.88 and a void ratio of 0.35 in the densest condition. If the relative density of the silty sand is 83%, compute the in-situ porosity.

The coefficient of permeability of fine sand is 0.12 cm/sec at a void ratio of 0.37. Estimate the increase in the permeability using the (a) kozeny-carman formula (b) casagrande formula of the same sand when its void ratio has increased by 0.45.

We know that

A certain saturated sand (S = 100%) has a moisture content of 27.9% and a specific gravity of solids of 2.61. It also has a maximum index void ratio of 0.90 and a minimum index void ratio of 0.33. Compute its relative density and classify its consistency. (Table on the right) Solution: Given the values of mmoisture content, specific gravity and degree of saturation, the void ratio can be estiamted as: e = Thus the relative density is found to be Dr = • According to the table, the soil is classified as %; soil. TABLE 3.3 CONSISTENCY OF COARSE-GRAINED SOILS AT VARIOUS RELATIVE DENSITIES (data from Lambe and Whitman, 1969) Relative Density, D,(%) 0-15 15-35 35-65 65-85 85-100 Classification Very loose Loose Medium denseª Dense Very dense "Lambe and Whitman used the term "medium," but "medium dense" is better because "medium" usually refers to the particle size distribution.