Question

Bouyant/Submerged Soil (Effective Unit Weight) Problem 1. In an undisturbed one cubic foot volume of soil obtained from...


Bouyant/Submerged Soil (Effective Unit Weight)

Problem 1. In an undisturbed one cubic foot volume of soil obtained from a test pit is found to have a wet weight. of 103.2 lbs. The dry weight of the sample 84.5 lbs. What would be the effective unit weight of such a soil if were submerged below water table. The specific gravity of the soil is determined to be 2.65 and void ratio

Answer

Given data-

The volume of soil sample (V) = 1 ft3

Wet weight (Ww) = 103.2 lbs

Dry weight (Wd) = 84.5 lbs

Specific gravity (G) = 2.65

 

Solution-

Dry Unit Weight-γd=WdV=84.51γd=84.5 lbs/ft3Also,γd=w1+eγw=Unit weight of water = 62.4 lbs/ft384.5=2.65×62.41+ee=0.9569Hence, The void ratio (e) = 0.9569Now,Effective Unit Weight-γ'=γsaturated-γwγsaturated=G+eγw1+eγsaturated=2.65+0.956962.41+0.9569γsaturated=115.01 lbs/ft3γ'=γsaturated-γwγ'=115.01-62.4γ'=52.61 lbs/ft3Hence, Effective Unit Weight=52.61 lbs/ft3

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