Geotechnical Engineering — Quiz 3

Questions in this quiz (10)

1. A test typically used to determine the maximum dry density of a soil is:

   • Sand-Cone Method
   • Nuclear Gauge
   • Sieve Analysis
   • Standard Proctor

2. Soil testing at a construction site indicates a soil has an in-place dry unit weight of $$115\ pcf$$. This soil has maximum and minimum dry unit weights of $$122\ pcf$$ and $$100\ pcf$$ respectively. The relative density is most nearly:

   • $$68\%$$
   • $$72\%$$
   • $$86\%$$
   • $$94\%$$

3. A soil profile consists of $$2.5\ m$$ of dry sand $$\gamma=16.8\ kN/m^3$$ overlying $$4\ m$$ saturated clay $$\gamma_{sat}=19.5\ kN/m^3$$. Water table at interface. Calculate effective stress at bottom of clay.

   • $$80.8\ \mathrm{kPa}$$
   • $$82.6\ \mathrm{kPa}$$
   • $$94.2\ \mathrm{kPa}$$
   • $$108.5\ \mathrm{kPa}$$

4. A point is located $$5\ m$$ below surface in saturated soil. $$\gamma_{sat}=19.8\ kN/m^3$$ and $$\gamma_w=9.81\ kN/m^3$$. Determine effective stress.

   • $$49.9\ \mathrm{kPa}$$
   • $$62.5\ \mathrm{kPa}$$
   • $$45.0\ \mathrm{kPa}$$
   • $$72.8\ \mathrm{kPa}$$

5. A soil has liquid limit $$62\%$$ and plastic limit $$28\%$$. Plasticity index is:

   • $$34\%$$
   • $$44\%$$
   • $$18\%$$
   • $$24\%$$

6. A clay sample has PI $$26\%$$ and clay fraction $$35\%$$. Activity is:

   • $$0.74$$
   • $$0.89$$
   • $$1.12$$
   • $$0.63$$

7. A Standard Proctor test uses mold volume $$950\ cm^3$$. Wet mass $$1820\ g$$. Water content $$13.8\%$$. Maximum dry unit weight is:

   • $$18.72\ \mathrm{kN/m}^3$$
   • $$17.95\ \mathrm{kN/m}^3$$
   • $$16.5\ \mathrm{kN/m}^3$$
   • $$19.48\ \mathrm{kN/m}^3$$

8. For a normally consolidated saturated clay subjected to rapid loading, which statement is correct regarding the critical design condition?

   • A. Drained condition is critical because it allows pore pressure buildup
   • B. Undrained condition is critical because excess pore pressure cannot dissipate
   • C. Both conditions yield same shear strength
   • D. Depends only on OCR

9. A 5 m wide strip footing supports a wall. Soil properties are $$\gamma=19.1\ kN/m^3$$, $$\phi=33^\circ$$, $$c=0$$. Depth of footing is $$4\ m$$. Terzaghi factors are $$N_c=48.1$$, $$N_q=21.2$$, $$N_\gamma=23.1$$. Determine ultimate bearing capacity.

   • A. $$800\ kN/m^2$$
   • B. $$1300\ kN/m^2$$
   • C. $$2000\ kN/m^2$$
   • D. $$2400\ kN/m^2$$

10. Which of the following is an incorrect statement regarding coefficient of permeability?

    • A. Constant head test measures permeability
    • B. Falling head test measures permeability
    • C. Permeability measures hydraulic conductivity
    • D. Coefficient of permeability is dimensionless