Foundation Engineering

Q. The ultimate bearing capacity of a soil is 300 kN/$m^2$. The depth of foundation is 1 m and unit weight of soil is 20 kN/$m^3$. Choosing a factor of safety of 2.5, the net safe bearing capacity is

1. 100 kN/$m^2$
2. 112 kN/$m^3$
3. 80 kN/$m^3$
4. 100.5 kN/$m^3$

Q.

What is damping and its types?

Q. The lateral earth pressure coefficient of a soil, $K_a$ for active state, $K_p$ for passive state and $K_0$ for at-rest condition, compare as

1. $K_0<K_a<K_p$
2. $K_a<K_0<K_p$
3. $K_a<K_p<K_0$
4. $K_p<K_0<K_a$

Q. Taylor's stability number $S_n$ is given by which one of the following expressions ? (c is cohesion , $F_c$ is fcator of safety, $\gamma$ is density of soil and H is the height of the slope).

1. $\frac{c}{F_c\gamma }$
2. $\frac{c}{\gamma H}$
3. $\frac{c}{F_c\gamma H}$
4. $\frac{c}{F_c(\gamma +H)}$

Q. Efficiency of a pile group is defined as

1. $\frac{Loadcarriedbythelargestpileinthegroup}{Loadcarriedbythesmallestpileinthegroup}$
2. $\frac{Maximumloadcarriedbyapileinthegroup}{Minimumloadcarriedbyapileinthegroup}$
3. $\frac{Minimumloadcarriedbyapileinthegroup}{Maximumloadcarriedbyapileinthegroup}$
4. $\frac{Averageloadcarriedbyapileinthegroup}{Loadcarriedbyasinglepile}$

Q. A raft foundation is to be constructed on a sandy soil. The maximum differential settlement and limiting maximum settlement as recommended by Indian standard code are :

Max. differential Limiting max.
settlement settlement

1. 40mm 65mm to 10mm
2. 40 mm 40mm to 65 mm
3. 25mm 65mm to 100mm
4. 25mm 40mm to 65mm

Q. The total active thrust on a vertical wall 3m high retaining a horizontal sand backfill (unit weight ${\gamma }_t=20KN/m^3$, angle of shearing resistance ${\varphi }^{\prime }={30}^{\circ }$) when the water table is at the bottom of the wall, will be:

1. 30 KN/m
2. 35 KN/m
3. 40 KN/m
4. 45 KN/m

Q. An unsupported excavation is made to the maximum possible depth in a clay soil having ${\gamma }_t$ = $18kN/m^3$, $C=100kN/m^2$, $\varphi ={30}^{\circ }$. The active earth pressure, according to Rankine's theory, at the base level of the excavation is

1. $115.47kN/m^2$
2. $54.36kN/m^2$
3. $27.18kN/m^2$
4. $13.0kN/m^2$

Q. A 6m height retaining wall having smooth vertical face and horizontal backfill. Top 3 m thick layer is sand $\varphi ={30}^{\circ }$ while the bottom layer is 3 m thick clay (C = 20 kPa). Assume unit weight for both sand and clay as $18kN/m^3$. The total active earth pressure per unit length of the wall (in K=kN/m) is

1. 150
2. 216
3. 156
4. 196

Q. Active earth pressure per meter length on the retaining wall with a smooth vertical back as shown in the given figure will be

1. 81 t
2. 27 t
3. 2 t
4. 1 t

Q. The value of bearing capacity factor for cohesion, $N_c^{\prime },$ for soil as per meyerhof, is taken as

1. 
   6.2
2. 
   12.0
3. 
   9.0
4. 
   5.14

Q. The ultimate bearing capacity of a surface strip footing on clay, according to Terzaghi's theory, is
Where C - unit cohesion,
$q_u$ = unconfined compressive strength,
and B - width of footing

1. 5.7 C
2. 5.14 C
3. $q_{u}B$
4. 9 C

Q. Why are weep holes provided at the back of retaining walls?

1. To reduce the active earth pressure on the walls.
2. To reduce the build-up of hydrostatic pressure.
3. To provide better compaction.
4. To increase the passive earth pressure.

Q. A footing 2 m $\times$ 1 m exerts a uniform pressure of 150 kN/$m^2$ on the soil. Assuming a load disperesion of 2 vertical to 1 horizantal, the average vertical stress (kN/$m^2$) at 1.0 m below the footing is

1. 50
2. 75
3. 80
4. 100

Q. Minimum centre to centre spacing of friction piles of diameter (D) as per BIS code is

1. 1.5D
2. 2D
3. 2.5D
4. 3D

Q. The bearing capacity factors $N_c{N}_{q}and{N}_{\gamma }$ are functions of

1. width and depth of footing
2. density of soil
3. cohesion of soil
4. angle of internal friction of soil

Q. The standard penetration resistance value obtained in a deep deposit of sand at a depth of 6.0 m was 28. The unit weight of sand is $18.0kN/m^3$. What is the corrected value of number of blows for overburden pressure?

1. 60
2. 57
3. 59
4. 55

Q. A retaining wall of height 8 m retains dry sand. In the initial state, the soil is loose and has a void ratio of 0.5, ${\gamma }_d=17.8kN/m^3$ and $\varphi ={30}^{\circ }$, Subsequently, the backfill is compacted to a state where void ratio is 0.4, ${\gamma }_d=18.8kN/m^3$ and $\varphi ={35}^{\circ }$, The ratio of initial passive thrust to the final passive thrust, according to Rankine's earth pressure theory, is

1. 0.38
2. 0.64
3. 0.77
4. 1.5

Q. A strip footing of width 1.5 m is laid at a depth of 1 m. The ultimate bearing capacity of soil (in $kN/m^2$) is ?


For $\varphi ={30}^{\circ },(N_c=19,N_q=8.3,N_{\gamma }=5.7)$

1. 403.5
2. 416.3
3. 424.8
4. 432.6

Q. The ultimate bearing capacity of a square footing on surface of a saturated clay having unconfined compression strength of 50 $kN/m^2$ (using skempton's equation) is

1. $250kN/m^2$
2. $180kN/m^2$
3. $150kN/m^2$
4. $125kN/m^2$

Q. In cohesive soils the depth of tension crack $\left(Z_{cr}\right)$ is likely to be

1. $Z_{cr}\ge \frac{2C}{\gamma }tan({45}^{\circ }-\frac{\varphi }{2})$
2. $Z_{cr}\ge \frac{2C}{\gamma }tan({45}^{\circ }+\frac{\varphi }{2})$
3. $Z_{cr}\ge \frac{4C}{\gamma }tan({45}^{\circ }-\frac{\varphi }{2})$
4. $Z_{cr}\ge \frac{4C}{\gamma }tan({45}^{\circ }+\frac{\varphi }{2})$

Q. The width and depth of a footing are 2 and 1.5 m respectively. The water table at the site is at a depth of 3 m below the ground level. The water table correction factor for the calculation of the bearing capacity of soil is

1. 
   0.875
2. 1.000
3. 
   0.925
4. 0.500

Q. If the coefficient of active earth pressure is 1/3, then what is the value of the coefficient of passive earth pressure?

1. 1/9
2. 1/3
3. 3
4. 1

Q. Westergaard's formula for vertical stress gives greater value of stress than that by the Boussinesq's formula, when r/z exceeds

1. 1.5
2. 2.5
3. 3.5
4. 4.0

Q. The group efficiency of pile group

1. Will be always less than $100\%$
2. Will be always greater than $100\%$
3. May be less than $100\%$ or more than $100\%$
4. Will be more than $100\%$ for pile group in cohesion less soils and less than $100\%$ for those in cohesive soils

Q. The contact pressure distribution under a rigid footing on a cohesionless soil would be

1. Uniform throughout
2. zero at centre and maximum at edges
3. zero at edges and maximum at centre
4. maximum at edges and minimum at centre

Q. As per Terzaghi's equation, the bearing capacity of strip footing resting on cohesive soil $(c=10kN/m^2)$ for unit depth and unit width $\left(assume{N}_{c}as5.7\right)$ is

1. $47kN/m^2$
2. $57kN/m^2$
3. $67kN/m^2$
4. $77kN/m^2$

Q. The vertical stress at some depth below the corner of a 2 m $\times$ 3 m rectangular footing due to a certain load intensity is 100$KN/m^2$. What will be the vertical stress in $KN/m^2$ below the centre of a 4 m $\times$ 6m rectangular footing at the same depth and same load intensity?

1. 25
2. 100
3. 200
4. 400

Q. The bearing capacity of a rectangular footing of plane dimension 1.5 m $\times$ 3 m resting on the surface on a sand deposit was estimated as 600 kN/$m^2$ when the water table is far below the base of the footing. The bearing capacities in kN/$m^2$ when the water level rises to depths of 3 m, 1.5 m and 0.5 m below the base of the footing are

1. 600, 600, 400
2. 600, 450, 350
3. 600, 500, 250
4. 600, 400, 250

Q. Standard penetration test (SPT) was conducted at a site. The recorded values of blow count for every 15 cm penetration at depth of 1 m are 5, 9 and 10 respectively. The water table was at the ground surface. The grain size classification showed that the size contained 40% fine sand and 60% silt. the value of SPT blow count(N) that should be used for overburden correction is ..........

1. 19