Quiz: Civil Engineering
Topic: Soil Mechanics
Each question carries 1 mark
Negative marking: 1/4 mark
Time: 10 Minutes
Q1. A soil sample is having a specific gravity 2.60 and a void ratio of 0.78. The water content required to fully saturate, the soil at the void ratio would be
Q2. If D_60,D_30 and D_10 of sizes of a soil grading are 4 mm, 2 mm and 0.5 mm, what will be the coefficient of uniformity of this soil?
Q3. For a sand having an internal friction of 30° the ratio of passive to active lateral earth pressure will be
Q4. With respect to c-ϕ soil in an infinite slope, identify if the following two statements are True of False:
I. The stable slop angel can be greater than ϕ
II. The factor of safety of the slope does not depend on the height of soil in the slope.
(a) Both statements are false
(b) I is true but II is false
(c) I is false but II is true
(d) Both statements are true
Q5. Which of the following assumptions is wrongly stated in regard to the Rankine’s theory of earth pressure?
(a) The back of the wall is smooth
(b) The soil mass in semi-infinite and homogeneous
(c) The ground surface is plane
(d) The retaining wall yields about the base
Q6. Test used to determine ultimate bearing capacity and probable settlement under a given loading is
(a) Plate load
(b) Bearing Load
(c) Settlement load
(d) Field load
Q7. Find the width of grillage foundation if the total load is 650 kN and safe bearing capacity of soil is 65 kN/m^2.
(a) 10 m
(b) 12 m
(c) 14 m
(d) 16 m
Q8. What will be the seepage velocity of soil having discharge velocity of 5×10^(-7) m/s and a void ratio of 0.50?
(a) 15×10^(-7) m/sec
(b) 30×10^(-7) m/sec
(c) 20×10^(-7) m/sec
(d) 10×10^(-7) m/sec
Q9. The rate of flow of water through a soil is proportional to the hydraulic gradient is demonstrated experimentally by:
(b) Henry Darcy
Q10. The relationship between air content of soil (a_c) and its degree of saturation (S_r) is expressed as
(d) None of these
Specific gravity (G)=2.60
Void ratio (e)=0.78
Water content (w)=?
Fully saturated i.e. S=1
Coefficient of uniformity (C_u )=D_60/D_10
Sol. Given, ϕ=30°
Active earth pressure coefficient k_a=(1-sinϕ)/(1+sinϕ)=(1-sin30)/(1+sin30)=0.5/1.5=1/3
〖Passive earth pressure coefficient k〗_P=(1+sinϕ)/(1-sinϕ)=(1+sin30)/(1-sin30)=1.5/0.5=3
Sol. → In stable slope angle is greater than critical angle (ϕ)
→ Factor of safety depend on Height of soil in slope
Sol. Rankine assumption in earth pressure analysis
→ soil is cohesionless.
→ Face of the wall in contact with backfill is vertical & smooth
→ ground surface is planer that may be horizontal & inclined
Sol. Plate load test used to determine ultimate bearing capacity and probable settlement under given loading.
Sol. Width of footing =(total load)/(safe bearing capacity)
Sol. Discharge velocity (V)=5×10^(-7) m\/sec
Void ratio (e)=0.50
Seepage velocity (V_s )=V/n
Sol. According to darcy law.
K= coefficient of permeability
S → degree of saturation
a_c → air content