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1) A property with flat ground is purchased in order to construct a building. A hole is dug in the soil in order to place a lift station. The excavated soil is piled next to the hole where the lift station will be placed. The resulting pile of soil has a conical shape and is 40 feet in diameter. The in-situ soil has the following characteristics: ɣ=115lb/ft³ Φ=30° What is the vertical pressure 20 feet below the surface of the ground directly underneath the peak (top) of the soil pile?  Note that: 1.2 BCY = 1 LCY

a) 2450 lb/ft²

b) 3258 lb/ft²

c) 3450 lb/ft²

d) 4258 lb/ft²

 A cantilevered retaining is to be constructed as shown in the drawing below. Considering the soil characteristics given, determine the following: 

2) What is the USCS group symbol for the soil?

a) GW

b) GP

c) SW

d) SP

3) What is the active force (Ra) on the wall?

a) 2,756 lbf

b) 525 lbf

c) 1,214 lbf

d) 14,880 lbf

Soil Characteristics: ɣ= 115lb/ft³ Φ= 30° λ= 90° β= 0° δ= 0° H= 8 feet Cu=7 Cz=4 < 5% finer than the no. 200 sieve > 50% coarser than the no. 200 sieve > 50% finer than the no. 4 sieve Relative density < 30%

4) What is the passive force (Rp) on the wall?

a) 1,214 lbf

b) 5,270 lbf

c) 8,875 lbf

d) 14,880 lbf

5) The qnet of the soil is most nearly:

a) 1 ton/ ft²

b) 1.5 tons/ ft²

c) 2 tons/ ft²

d) 4 tons/ ft²

6) If a round pile with a diameter of 10 inches were to be driven into this soil, what is most likely the depth at which the tip-point bearing capacity becomes constant?

a) 8.3 feet

b) 16.6 feet

c) 100 feet

d) 200 feet

7) The maximum lateral pressure of a 10 foot-deep braced cut in this soil would most nearly be:

a) 247 lbf/ ft²

b) 800 lbf/ ft²

c) 1,150 lbf/ ft²

d) 2,243 lbf/ ft²

8) The coefficient of permeability of this soil would most nearly be:

a) >5 10

b) >2.5 10

c) 5 10

d) >5 10

9) What value for cohesion would this soil have:

a) 0 lbf/ ft²

b) 1,050 lbf/ ft²

c) 0°

d) 30°

10) Generally, clay is good in _________________but poor in _________________:

a) foundations, excavations

b) excavations, foundations

c) bearing capacity, shear strength

d) shear strength, bearing capacity