Soils, Foundations, and Settlements - Questions

1. A sample moist soil has the following attributes:

Volume = 0.52 ft^3 (as sampled)
Mass = 56.75 lbm (as sampled)
= 48.7 lbm (after oven drying)
SG of solids = 2.7

After drying the soil was run through a set of sieves.

Sieve ---------- % finer by mass
½ in ----------- 52
No 4 ---------- 37
No 10 ---------- 32
No 20 ---------- 23
No 40 ---------- 11
No 60 ---------- 7
No 100 ---------- 4

a) what is the density of the in situ soil?
b) What is the unit weight of the in situ soil?
c) What is the void ratio of the in situ soil?
d) What is the porosity of the in situ soil?
e) What is the degree of saturation of the in situ soil?
f) What is the uniformity coefficient?
g) What is the coefficient of curvature?
h) What is the USCS classification?
i) What is the AASHTO classification?


2. A triaxial shear test is performed on well drained sand. At failure the normal stress was 6300 lbf/ft^2 and shear stress was 4200 lbf/ft^2.
a) what’s the internal angle of friction?
b) What is the maximum principal stress?

3. A sample of sand has a relative density of 39% with solids SG = 2.7. The minimum void raito is 0.46 and the maximum is 0.96
a) what is the specific weight of the sand in saturated condition?
b) If the sand is compacted to a relative density of 70%, what will be the decrease of thickness of a layer 4 ft thick.