68 + Interview Questions in Foundation Engineering Page 1 InterviewSolution

1.	A timber pile of length 8m and diameter of 0.2m is driven with a 20 kN drop hammer, falling freely from a height of 1.5m. The total penetration of the Pile in the last 5 blows is 40mm. Use the engineering news record expression. Assume a factor of safety of 6 and empirical factor (allowing reducing in the theoretical set, due to energy losses) of 2.5 cm. The safe load carrying capacity Of the pile (in kN, round off to 2 decimal places) is151.515
Answer» A timber pile of length 8m and diameter of 0.2m is driven with a 20 kN drop hammer, falling freely from a height of 1.5m. The total penetration of the Pile in the last 5 blows is 40mm. Use the engineering news record expression. Assume a factor of safety of 6 and empirical factor (allowing reducing in the theoretical set, due to energy losses) of 2.5 cm. The safe load carrying capacity Of the pile (in kN, round off to 2 decimal places) is 151.515

Discussion

2.	If σh,σv,σ′handσ′v represent the total horizontal stress, total vertical stress, effective horizontal stress and effective vertical stress on a soil element, respectively. The coefficient of earth pressure at rest is given by
Answer» If $σ_{h}, σ_{v}, σ_{h}^{'} a n d σ_{v}^{'}$ represent the total horizontal stress, total vertical stress, effective horizontal stress and effective vertical stress on a soil element, respectively. The coefficient of earth pressure at rest is given by

Discussion

3.	What is the intensity of active earth pressure at a depth of 10.0 m in dry sand with an angle of shearing resistance of 30∘ and unit weight of 18 kN/m3?
Answer» What is the intensity of active earth pressure at a depth of 10.0 m in dry sand with an angle of shearing resistance of $30^{\circ}$ and unit weight of $18 k N / m^{3}$ ?

Discussion

4.	An earthen dam of height H is made of cohesive soilwhose cohesion and unit weight are c and γrespectively.If the factor of safety against cohesion is Fc, the Taylor's stability
Answer» $An earthen dam of height H is made of cohesive soil whose cohesion and unit weight are c and γ r e s p e c t i v e l y . If the factor of safety against cohesion is F_{c}, the Taylor's stability$

Discussion

5.	In the plate load test, if the break on the log-log plot between the load intensity q and settlement is not well defined, the ultimate load is taken corresponding to a settlement of:
Answer» In the plate load test, if the break on the log-log plot between the load intensity q and settlement is not well defined, the ultimate load is taken corresponding to a settlement of:

Discussion

6.	For a vertical concentrated load acting on the surface of a semi-infinite elastic soil mass, the vertical normal stress at depth 'z' is proportional to
Answer» For a vertical concentrated load acting on the surface of a semi-infinite elastic soil mass, the vertical normal stress at depth 'z' is proportional to

Discussion

7.	A raft of 6 m×9 m is founded at a depth of 3m in a cohesive soil having c=120kN/m2. The ultimate net bearing capacity of the soil using the Terzaghi's theory will be nearly
Answer» A raft of $6 m \times 9 m$ is founded at a depth of 3m in a cohesive soil having $c = 120 k N / m^{2}$ . The ultimate net bearing capacity of the soil using the Terzaghi's theory will be nearly

Discussion

8.	A precast concrete pile is driven with a 50 kN hammer falling through a height of 1.0 m with an efficiency of 0.6. The set value observed is 4 mm per blow and the combined temporary compression of the pile, cushion and the ground is 6 mm. As per Modified Hiley Formula, the ultimate resistance of the pile is
Answer» A precast concrete pile is driven with a $50 kN$ hammer falling through a height of $1.0 m$ with an efficiency of 0.6. The set value observed is $4 mm$ per blow and the combined temporary compression of the pile, cushion and the ground is $6 mm$ . As per Modified Hiley Formula, the ultimate resistance of the pile is

Discussion

9.	A plate load test was conducted by using a 60 cm square plate on the top of a sandy deposit, the ultimate bearing capacity was observed as 55 kN/m2. What will be the ultimate bearing capacity for a strip footing of 1.2 m width to be placed on the surface of the same soil?
Answer» A plate load test was conducted by using a 60 cm square plate on the top of a sandy deposit, the ultimate bearing capacity was observed as $55 k N / m^{2} .$ What will be the ultimate bearing capacity for a strip footing of 1.2 m width to be placed on the surface of the same soil?

Discussion

10.	A concentrated load of 50 kN acts on the surface of ground. The increase in vertical stress directly below the load at a depth of 4 m will be (Value of influence factor is 0.48)
Answer» A concentrated load of 50 kN acts on the surface of ground. The increase in vertical stress directly below the load at a depth of 4 m will be (Value of influence factor is 0.48)

Discussion

11.	Given that for a soil deposit,Ko= earth pressure coefficient at restKa= active earth pressure coefficient Kp= passive earth pressure coefficientμ= Poisson's ratio.The value of (1−μ)/μ is given by
Answer» Given that for a soil deposit, $K_{o} =$ earth pressure coefficient at rest $K_{a} =$ active earth pressure coefficient $K_{p} =$ passive earth pressure coefficient $μ =$ Poisson's ratio. The value of $(1 - μ) / μ$ is given by

Discussion

12.	The vertical stress at depth, z directly below the point load P is (k is a constant)
Answer» The vertical stress at depth, z directly below the point load P is (k is a constant)

Discussion

13.	A rigid smooth retaining wall of height 7 m with vertical back face retains saturated clay as backfill. The saturated unit weight and undrained cohesion of the backfill are 17.2kN/m3 and 20 kPa, respectively. The difference in the active lateral forces on the wall (in KN per meter length of wall up to two decimal places), before and after the occurrence of tension cracks is 46.6
Answer» A rigid smooth retaining wall of height 7 m with vertical back face retains saturated clay as backfill. The saturated unit weight and undrained cohesion of the backfill are $17.2 k N / m^{3}$ and 20 kPa, respectively. The difference in the active lateral forces on the wall (in KN per meter length of wall up to two decimal places), before and after the occurrence of tension cracks is 46.6

Discussion

14.	An infinitely long slope is made up of a c−ϕ soil having the properties : cohesion (c) = 20 kPa and dry unit wt(γd)=16kN/m3 . The angle of inclination and critical height of the slope are 40∘ and 5 m respectively. To maintain the limiting equilibrium, the angle of internal friction of the soil (in degree)22.44
Answer» An infinitely long slope is made up of a $c - ϕ$ soil having the properties : cohesion (c) = 20 kPa and dry unit wt $(γ_{d}) = 16 k N / m^{3}$ . The angle of inclination and critical height of the slope are $40^{\circ}$ and 5 m respectively. To maintain the limiting equilibrium, the angle of internal friction of the soil (in degree) 22.44

Discussion

15.	In which one of the following conditions, is the pile system as shown in figure highly inappropriate ?
Answer» In which one of the following conditions, is the pile system as shown in figure highly inappropriate ?

Discussion

16.	The settlement of prototype in clayey material may be estimated using plate load test data from the following expression:
Answer» The settlement of prototype in clayey material may be estimated using plate load test data from the following expression:

Discussion

17.	The gross bearing capacity of a footing is 450kN/m2. If the footing is 1.5 m wide and is at a depth of 1 m in a clayey soil which has a unit weight of 20kN/m3, then the net bearing capacity is
Answer» The gross bearing capacity of a footing is $450 k N / m^{2}$ . If the footing is 1.5 m wide and is at a depth of 1 m in a clayey soil which has a unit weight of $20 k N / m^{3}$ , then the net bearing capacity is

Discussion

18.	Efficiency of a pile group is defined as
Answer» Efficiency of a pile group is defined as

Discussion

19.	A group of nine piles in a 3×3 square pattern in embedded in a soil strata comprising dense sand underlying recently filled clay layer, as shown in the figure. The perimeter of an individual pile is 126 cm. The size of pile group is 240 cm×240 cm. The recently filled clay has undrained shear strength of 15 kPa and unit weight of 16 kN/m3. The negative frictional load in (in kN, up to two decimal places) acting on the pile group is472.32
Answer» A group of nine piles in a $3 \times 3$ square pattern in embedded in a soil strata comprising dense sand underlying recently filled clay layer, as shown in the figure. The perimeter of an individual pile is $126 cm$ . The size of pile group is $240 cm \times 240 cm$ . The recently filled clay has undrained shear strength of $15 kPa$ and unit weight of $16 {kN/m}^{3}$ . The negative frictional load in (in kN, up to two decimal places) acting on the pile group is 472.32

Discussion

20.	If a point load of 50 kN is applied on a homogenous, isotropic soil mass. What will be the stress at 5 m below the point of application of load as per Boussinesq theory?
Answer» If a point load of 50 kN is applied on a homogenous, isotropic soil mass. What will be the stress at 5 m below the point of application of load as per Boussinesq theory?

Discussion

21.	The ultimate load capacity of a 10 m long concrete pile of square cross-section 500 mm×500 mm driven into a homogeneous clay layer having undrained cohesion value of 40 kPa is 700 kN. If the cross-section of the pile is reduced to 250 mm×250 mm and the length of the pile is increased to 20 m, the ultimate load capacity will be
Answer» The ultimate load capacity of a $10 m$ long concrete pile of square cross-section $500 mm \times 500 mm$ driven into a homogeneous clay layer having undrained cohesion value of $40 kPa$ is $700 kN$ . If the cross-section of the pile is reduced to $250 mm \times 250 mm$ and the length of the pile is increased to $20 m$ , the ultimate load capacity will be

Discussion

22.	Match the items of List I with List II and select the correct answer using the codes given below the list.(A)Modulus of subgrade reaction1.Cyclic pile load test(B)Relative density and strength2.Pressure meter test(C)Skin friction and point bearing resistance 3.Plate load test(D)Elastic constants4.Standard penetration tests5.Dynamic cone penetration test
Answer» Match the items of List I with List II and select the correct answer using the codes given below the list. $\begin{matrix} (A) & Modulus of subgrade reaction & 1. & Cyclic pile load test (B) & Relative density and strength & 2. & Pressure meter test (C) & Skin friction and point bearing resistance & 3. & Plate load test (D) & Elastic constants & 4. & Standard penetration tests 5. & Dynamic cone penetration test \end{matrix}$

Discussion

23.	Consider a square-shaped area ABCD on the ground with this centre at M as shown in the figure. Four concentrated vertical loads of P = 5000 kN are applied on this area, one at each corner.The vertical stress increment (in kPa up to one decimal place) due to these loads according to the Boussinesq's equation at a point 5m right below M is 190.84
Answer» Consider a square-shaped area ABCD on the ground with this centre at M as shown in the figure. Four concentrated vertical loads of P = 5000 kN are applied on this area, one at each corner. The vertical stress increment (in kPa up to one decimal place) due to these loads according to the Boussinesq's equation at a point 5m right below M is 190.84

Discussion

24.	A retaining wall with vertical back retains a cohesionless dry backfill at an inclination of β with the horizontal. The backfill has an angle of internal friction ϕ, unit weigth γ and height of the wall is H. The passive earth pressure on the wall is given by (where Pp= Total passive earth pressure)
Answer» A retaining wall with vertical back retains a cohesionless dry backfill at an inclination of $β$ with the horizontal. The backfill has an angle of internal friction $ϕ,$ unit weigth $γ$ and height of the wall is $H .$ The passive earth pressure on the wall is given by (where $P_{p}$ = Total passive earth pressure)

Discussion

25.	For the strip footing on a saturated clay, for the given failure surface (fig. 3. 12), the bearing capacity equation takes the form whereCu =undrained shear strengthϕu = angle of internal frictionB = width of strip footingqc ultimate bearing capacity of soil
Answer» For the strip footing on a saturated clay, for the given failure surface (fig. 3. 12), the bearing capacity equation takes the form where $C_{u}$ =undrained shear strength $ϕ_{u}$ = angle of internal friction B = width of strip footing $q_{c}$ ultimate bearing capacity of soil

Discussion

26.	A concentrated load of 500kN is applied on an elastic half space. The ratio of the increase in vertical normal stress at depth of 2m and 4m along the point of the loading, as per Boussinesq's theory, would be .4
Answer» A concentrated load of 500kN is applied on an elastic half space. The ratio of the increase in vertical normal stress at depth of 2m and 4m along the point of the loading, as per Boussinesq's theory, would be . 4

Discussion

27.	The ultimate bearing capacity of a square footing on surface of a saturated clay having unconfined compression strength of 50 kN/m2 (using skempton's equation) is
Answer» The ultimate bearing capacity of a square footing on surface of a saturated clay having unconfined compression strength of 50 $k N / m^{2}$ (using skempton's equation) is

Discussion

28.	The lateral earth pressure coefficient of a soil, Ka for active state, Kp for passive state and K0 for at-rest condition, compare as
Answer» 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

Discussion

29.	A singly-reamed, 8 m long, RCC pile (as shown in the below figure) weighing 20 kN with 350 mm shaft diameter and 750 mm under-ream diameter is installed within stiff, saturated silty clay (undrained shear strength is 50 kPa, adhesion factor is 0.3, and the applicable bearing capacity factor is 9) to counteract the impact of soil swelling on a structure constructed above. Neglecting suction and the contribution of the under-ream to the adhesive shaft capacity, what would be the estimated ultimate tensile capacity (rounded off to the nearest integer value in kN) of the pile?
Answer» A singly-reamed, $8 m$ long, RCC pile (as shown in the below figure) weighing $20 kN$ with $350 mm$ shaft diameter and $750 mm$ under-ream diameter is installed within stiff, saturated silty clay (undrained shear strength is $50 kPa$ , adhesion factor is 0.3, and the applicable bearing capacity factor is 9) to counteract the impact of soil swelling on a structure constructed above. Neglecting suction and the contribution of the under-ream to the adhesive shaft capacity, what would be the estimated ultimate tensile capacity (rounded off to the nearest integer value in $kN$ ) of the pile?

Discussion

30.	A rectangular footing 1 m×2 m is placed at a depth of 2 m in a saturated clay having an unconfined compressive strength of 100kN/m2. According to Skempton, the net ultimate bearing capacity is
Answer» A rectangular footing $1 m \times 2 m$ is placed at a depth of 2 m in a saturated clay having an unconfined compressive strength of $100 k N / m^{2}$ . According to Skempton, the net ultimate bearing capacity is

Discussion

31.	The vertical stress at point P1 due to the point load Q on the ground surface as shown in figure is σz. According to Boussinesq's equation, the vertical stress at point P2 Shown in figure will be
Answer» The vertical stress at point $P_{1}$ due to the point load Q on the ground surface as shown in figure is $σ_{z}$ . According to Boussinesq's equation, the vertical stress at point $P_{2}$ Shown in figure will be

Discussion

32.	A square footing of 4 m. side is placed at 1 m depth in a sand deposit. The dry unit weight (γ) of sand is 15 kN/m3. This footing has an ultimate bearing capacity of 600 kPa. Consider the depth factor; dq=dγ=1.0 and the bearing capacity factor : Nγ=18.75 . This footing is placed at a depth of 2 m in the same soil deposit. For a factor of safety of 3.0 for Terzaghi's theory, the safe bearing capacity (in kPa) of this footing would be270
Answer» A square footing of 4 m. side is placed at 1 m depth in a sand deposit. The dry unit weight ( $γ$ ) of sand is 15 kN/ $m^{3}$ . This footing has an ultimate bearing capacity of 600 kPa. Consider the depth factor; $d_{q} = d_{γ} = 1.0$ and the bearing capacity factor : $N_{γ} = 18.75$ . This footing is placed at a depth of 2 m in the same soil deposit. For a factor of safety of 3.0 for Terzaghi's theory, the safe bearing capacity (in kPa) of this footing would be 270

Discussion

33.	The nature of contact pressure distribution under a rigid footing resting on a sandy soil and subjected to uniformly distributed load is as shown in:
Answer» The nature of contact pressure distribution under a rigid footing resting on a sandy soil and subjected to uniformly distributed load is as shown in:

Discussion

34.	A rectangular footing L×B is to be placed at a depth D below ground level such that DB<2.5 . The factor Nc to be used in deciding of the allowable bearing capacity for the footing as given by Skempton is calculated using the equation (where, NCR=NC for rectangular footing, NCS=NC at surface )
Answer» A rectangular footing $L \times B$ is to be placed at a depth D below ground level such that $\frac{D}{B} < 2.5$ . The factor $N_{c}$ to be used in deciding of the allowable bearing capacity for the footing as given by Skempton is calculated using the equation (where, $N_{C R} = N_{C}$ for rectangular footing, $N_{C S} = N_{C}$ at surface )

Discussion

35.	A plate load test is conducted on a cohesionless soil with a test plate having width Bp(cm) and settlement of this plate Sp(cm) is obtained at the same load intensity as a foundation. A footing having a width Bf(cm) is to be constructed as foundation. What is the settlement Sf(cm) experienced by this footing?
Answer» A plate load test is conducted on a cohesionless soil with a test plate having width $B_{p} (c m)$ and settlement of this plate $S_{p} (c m)$ is obtained at the same load intensity as a foundation. A footing having a width $B_{f} (c m)$ is to be constructed as foundation. What is the settlement $S_{f} (c m)$ experienced by this footing?

Discussion

36.	The infinite sand slope shown in the figure is one the verge of sliding failure. The ground water table coincides with the ground surface. Unit weight of water γw=9.81kN/m3.The value of the effective angle of internal friction (in degrees upto one decimal place) of the sand is 34.33
Answer» The infinite sand slope shown in the figure is one the verge of sliding failure. The ground water table coincides with the ground surface. Unit weight of water $γ_{w} = 9.81 k N / m^{3}$ . The value of the effective angle of internal friction (in degrees upto one decimal place) of the sand is 34.33

Discussion

37.	σz is the vertical stress at a depth equal to Z in the soil mass due to a surface point load Q. The vertical stress at depth equal to 2Z will be
Answer» $σ_{z}$ is the vertical stress at a depth equal to Z in the soil mass due to a surface point load Q. The vertical stress at depth equal to 2Z will be

Discussion

38.	For a sample of dry, cohesionless soil with friction angle ϕ, the failure plane will be inclined to the major principal plane by an angle equal to
Answer» For a sample of dry, cohesionless soil with friction angle $ϕ$ , the failure plane will be inclined to the major principal plane by an angle equal to

Discussion

39.	A square footing of 2 m sides rests on the surface of a homogeneous soil bed having the properties: cohesion c = 24 kPa, angle of internal friction ϕ = 25o, and unit weight γ = 18kN/m3. Terzaghi's bearing capacity factor ϕ= 25o are Nc = 25.1, Nq = 12.7, Nγ = 9.7, N′c = 14.8, N′q = 5.6, and N′γ = 3.2. The ultimate bearing capacity of the foundation (in kPa, round off to 2 decimal places) is353.92
Answer» A square footing of 2 m sides rests on the surface of a homogeneous soil bed having the properties: cohesion c = 24 kPa, angle of internal friction $ϕ$ = $25^{o}$ , and unit weight $γ$ = $18 k N / m^{3}$ . Terzaghi's bearing capacity factor $ϕ$ = $25^{o}$ are $N_{c}$ = 25.1, $N_{q}$ = 12.7, $N_{γ}$ = 9.7, $N_{c}^{'}$ = 14.8, $N_{q}^{'}$ = 5.6, and $N_{γ}^{'}$ = 3.2. The ultimate bearing capacity of the foundation (in kPa, round off to 2 decimal places) is 353.92

39.

A square footing of 2 m sides rests on the surface of a homogeneous soil bed having the properties: cohesion c = 24 kPa, angle of internal friction ϕ = 25o, and unit weight γ = 18kN/m3. Terzaghi's bearing capacity factor ϕ= 25o are Nc = 25.1, Nq = 12.7, Nγ = 9.7, N′c = 14.8, N′q = 5.6, and N′γ = 3.2. The ultimate bearing capacity of the foundation (in kPa, round off to 2 decimal places) is353.92

Answer»

A square footing of 2 m sides rests on the surface of a homogeneous soil bed having the properties: cohesion c = 24 kPa, angle of internal friction $ϕ$ = $25^{o}$ , and unit weight $γ$ = $18 k N / m^{3}$ . Terzaghi's bearing capacity factor $ϕ$ = $25^{o}$ are $N_{c}$ = 25.1, $N_{q}$ = 12.7, $N_{γ}$ = 9.7, $N_{c}^{'}$ = 14.8, $N_{q}^{'}$ = 5.6, and $N_{γ}^{'}$ = 3.2. The ultimate bearing capacity of the foundation (in kPa, round off to 2 decimal places) is

353.92

Discussion

40.	For the trial slip circle shown in Figure, Calculate the factor of safety. [Data: weight of the soil = 346 KN/m, unit weight of the soil = 19KN/m3, Cu=20KN/m2]1.14
Answer» For the trial slip circle shown in Figure, Calculate the factor of safety. [Data: weight of the soil = 346 KN/m, unit weight of the soil = $19 K N / m^{3},$ $C_{u} = 20 K N / m^{2}]$ 1.14

Discussion

41.	When a load test was conducted by putting a 60 cm square plate on top of a sandy deposit, the ultimate bearing capacity was observed as 60kN/m2. What is the ultimate bearing capacity for a strip footing of 1.2 m width to be placed on the surface of the same soil?
Answer» When a load test was conducted by putting a 60 cm square plate on top of a sandy deposit, the ultimate bearing capacity was observed as $60 k N / m^{2}$ . What is the ultimate bearing capacity for a strip footing of 1.2 m width to be placed on the surface of the same soil?

Discussion

42.	A 4 m wide strip footing is founded at a depth of 1.5 m below the ground surface in a c−ϕ soil as shown in the figure. The water table is at a depth of 5.5 m below ground surface. the soil properties are c' = 25 kN/m2, ϕ′ = 28.63o, γsat = 19 kN/m3, γbulk = 17 kN/m3 and γw = 9.81 kN/m3. the values of bearing capacity factors for different ϕ′ are given below. ϕ′NcNqNγ15∘12.94.42.520∘17.77.45.025∘25.112.79.730∘37.222.519.7Using Terzaghi's bearing capacity equation and a factor of safety Fs=2.5, the net safe bearing capacity (expressed in kN/m2) for local shear failure of the soil is298.48
Answer» A 4 m wide strip footing is founded at a depth of 1.5 m below the ground surface in a $c - ϕ$ soil as shown in the figure. The water table is at a depth of 5.5 m below ground surface. the soil properties are c' = 25 kN/ $m^{2}$ , $ϕ^{'}$ = ${28.63}^{o}$ , $γ_{s a t}$ = 19 kN/ $m^{3}$ , $γ_{b u l k}$ = 17 kN/ $m^{3}$ and $γ_{w}$ = 9.81 kN/ $m^{3}$ . the values of bearing capacity factors for different $ϕ^{'}$ are given below. $\begin{matrix} ϕ^{^{'}} & N_{c} & N_{q} & N_{γ} 15^{\circ} & 12.9 & 4.4 & 2.5 20^{\circ} & 17.7 & 7.4 & 5.0 25^{\circ} & 25.1 & 12.7 & 9.7 30^{\circ} & 37.2 & 22.5 & 19.7 \end{matrix}$ Using Terzaghi's bearing capacity equation and a factor of safety $F_{s} = 2.5,$ the net safe bearing capacity (expressed in kN/ $m^{2}$ ) for local shear failure of the soil is 298.48

Discussion

43.	A reinforced concrete circular pile of 12 m length and 0.6 m diameter is embedded in stiff clay which has an undrained unit cohesion of 110 kN/m2. The adhesion factor is 0.5. The Net ultimate Pullout (Uplift) Load for the pile (in kN, round off to 1 decimal place) is 1244.07
Answer» A reinforced concrete circular pile of $12 m$ length and $0.6 m$ diameter is embedded in stiff clay which has an undrained unit cohesion of $110 {kN/m}^{2}$ . The adhesion factor is 0.5. The Net ultimate Pullout (Uplift) Load for the pile (in kN, round off to 1 decimal place) is 1244.07

Discussion

44.	A square footing (2 m × 2 m ) is subject to an inclined point load, P as shown in the figure below. The water table is located well below the base of the footing. Considering one way eccentricity, the net safe load carrying capacity of the footing for a factor of safety of 3.0 is __ kN.The following factor may be used:Bearing capacity factors : Nq = 33.3, Nγ = 37.16,shape factors : Fqs = Fγs = 1.314Depth factors : Fqd = Fγd = 1.113Inclination factors : Fqi =0.444,Fγi = 0.02441.71
Answer» A square footing (2 m $\times$ 2 m ) is subject to an inclined point load, P as shown in the figure below. The water table is located well below the base of the footing. Considering one way eccentricity, the net safe load carrying capacity of the footing for a factor of safety of 3.0 is __ kN. The following factor may be used: Bearing capacity factors : $N_{q}$ = 33.3, $N_{γ}$ = 37.16, shape factors : $F_{q s}$ = $F_{γ}$ $_{s}$ = 1.314 Depth factors : $F_{q d}$ = $F_{γ}$ $_{d}$ = 1.113 Inclination factors : $F_{q i} = 0.444, F_{γ}$ $_{i}$ = 0.02 441.71

Discussion

45.	A point load of 650 kN is applied on the surface of a thick layer of clay. Using Boussinesq's elastic analysis, what is approximate value of the estimated vertical stress at a depth 2 m and a radial distance of 1.0 m from the point of application of load?
Answer» A point load of 650 kN is applied on the surface of a thick layer of clay. Using Boussinesq's elastic analysis, what is approximate value of the estimated vertical stress at a depth 2 m and a radial distance of 1.0 m from the point of application of load?

Discussion

46.	A fully submerged infinite sandy slope has an inclination of 30∘ with the horizontal. The saturated unit weight and effective angle of internal friction of sand are 18KN/m3 and 38∘, respectively. The unit weight of water is 10 KN/m3. Assume that the seepage is parallel to the slope. Against shear failure of the slope, the factor of safety (round off to two decimal places) is 0.6014
Answer» A fully submerged infinite sandy slope has an inclination of $30^{\circ}$ with the horizontal. The saturated unit weight and effective angle of internal friction of sand are $18 K N / m^{3}$ and $38^{\circ}$ , respectively. The unit weight of water is 10 KN/ $m^{3}$ . Assume that the seepage is parallel to the slope. Against shear failure of the slope, the factor of safety (round off to two decimal places) is 0.6014

Discussion

47.	A soil profile above the rock surface for a 30∘ infinite slope is shown in the figure where Su is the undrained shear strength and γt is unit weight. The slip will occur at a depth of (assume ϕ=0)
Answer» A soil profile above the rock surface for a $30^{\circ}$ infinite slope is shown in the figure where $S_{u}$ is the undrained shear strength and $γ_{t}$ is unit weight. The slip will occur at a depth of (assume $ϕ = 0$ )

Discussion

48.	A sampling tube with a cutting edge is used for extracting the samples. The sampling tube has the following dimensions:Inner diameter of cutting edge=DcOuter diameter of cutting edge=Dw Inner diameter of the sampling tube=DsOuter diameter of the sampling tube=DtWhat is the area ratio Ar of the sampling tube ?
Answer» A sampling tube with a cutting edge is used for extracting the samples. The sampling tube has the following dimensions: $Inner diameter of cutting edge = D_{c}$ $Outer diameter of cutting edge = D_{w}$ $Inner diameter of the sampling tube = D_{s}$ $Outer diameter of the sampling tube = D_{t}$ What is the area ratio $A_{r}$ of the sampling tube ?

Discussion

49.	A strip footing is resting on the ground surface of a pure clay bed having an undrained cohesion Cu. The ultimate bearing capacity of the footing is equal to
Answer» A strip footing is resting on the ground surface of a pure clay bed having an undrained cohesion $C_{u}$ . The ultimate bearing capacity of the footing is equal to

Discussion

50.	The infinite sand slope shown in the figure is on the verge of sliding failure. The ground water table coincides with ground surface. The value of effective angle of internal friction (in degrees, correct upto one decimal place) of sand is ?.(Take γw=10kN/m3)
Answer» The infinite sand slope shown in the figure is on the verge of sliding failure. The ground water table coincides with ground surface. The value of effective angle of internal friction (in degrees, correct upto one decimal place) of sand is ?. (Take $γ_{w} = 10 k N / m^{3}$ )

Discussion

Explore topic-wise InterviewSolutions in .

If σh,σv,σ′handσ′v represent the total horizontal stress, total vertical stress, effective horizontal stress and effective vertical stress on a soil element, respectively. The coefficient of earth pressure at rest is given by

What is the intensity of active earth pressure at a depth of 10.0 m in dry sand with an angle of shearing resistance of 30∘ and unit weight of 18 kN/m3?

An earthen dam of height H is made of cohesive soilwhose cohesion and unit weight are c and γrespectively.If the factor of safety against cohesion is Fc, the Taylor's stability

In the plate load test, if the break on the log-log plot between the load intensity q and settlement is not well defined, the ultimate load is taken corresponding to a settlement of:

For a vertical concentrated load acting on the surface of a semi-infinite elastic soil mass, the vertical normal stress at depth 'z' is proportional to

A raft of 6 m×9 m is founded at a depth of 3m in a cohesive soil having c=120kN/m2. The ultimate net bearing capacity of the soil using the Terzaghi's theory will be nearly

A plate load test was conducted by using a 60 cm square plate on the top of a sandy deposit, the ultimate bearing capacity was observed as 55 kN/m2. What will be the ultimate bearing capacity for a strip footing of 1.2 m width to be placed on the surface of the same soil?

A concentrated load of 50 kN acts on the surface of ground. The increase in vertical stress directly below the load at a depth of 4 m will be (Value of influence factor is 0.48)

Given that for a soil deposit,Ko= earth pressure coefficient at restKa= active earth pressure coefficient Kp= passive earth pressure coefficientμ= Poisson's ratio.The value of (1−μ)/μ is given by

The vertical stress at depth, z directly below the point load P is (k is a constant)

In which one of the following conditions, is the pile system as shown in figure highly inappropriate ?

The settlement of prototype in clayey material may be estimated using plate load test data from the following expression:

The gross bearing capacity of a footing is 450kN/m2. If the footing is 1.5 m wide and is at a depth of 1 m in a clayey soil which has a unit weight of 20kN/m3, then the net bearing capacity is

Efficiency of a pile group is defined as

If a point load of 50 kN is applied on a homogenous, isotropic soil mass. What will be the stress at 5 m below the point of application of load as per Boussinesq theory?

For the strip footing on a saturated clay, for the given failure surface (fig. 3. 12), the bearing capacity equation takes the form whereCu =undrained shear strengthϕu = angle of internal frictionB = width of strip footingqc ultimate bearing capacity of soil

A concentrated load of 500kN is applied on an elastic half space. The ratio of the increase in vertical normal stress at depth of 2m and 4m along the point of the loading, as per Boussinesq's theory, would be .4

The ultimate bearing capacity of a square footing on surface of a saturated clay having unconfined compression strength of 50 kN/m2 (using skempton's equation) is

The lateral earth pressure coefficient of a soil, Ka for active state, Kp for passive state and K0 for at-rest condition, compare as

A rectangular footing 1 m×2 m is placed at a depth of 2 m in a saturated clay having an unconfined compressive strength of 100kN/m2. According to Skempton, the net ultimate bearing capacity is

The vertical stress at point P1 due to the point load Q on the ground surface as shown in figure is σz. According to Boussinesq's equation, the vertical stress at point P2 Shown in figure will be

The nature of contact pressure distribution under a rigid footing resting on a sandy soil and subjected to uniformly distributed load is as shown in:

A rectangular footing L×B is to be placed at a depth D below ground level such that DB&lt;2.5 . The factor Nc to be used in deciding of the allowable bearing capacity for the footing as given by Skempton is calculated using the equation (where, NCR=NC for rectangular footing, NCS=NC at surface )

The infinite sand slope shown in the figure is one the verge of sliding failure. The ground water table coincides with the ground surface. Unit weight of water γw=9.81kN/m3.The value of the effective angle of internal friction (in degrees upto one decimal place) of the sand is 34.33

σz is the vertical stress at a depth equal to Z in the soil mass due to a surface point load Q. The vertical stress at depth equal to 2Z will be

For a sample of dry, cohesionless soil with friction angle ϕ, the failure plane will be inclined to the major principal plane by an angle equal to

For the trial slip circle shown in Figure, Calculate the factor of safety. [Data: weight of the soil = 346 KN/m, unit weight of the soil = 19KN/m3, Cu=20KN/m2]1.14

When a load test was conducted by putting a 60 cm square plate on top of a sandy deposit, the ultimate bearing capacity was observed as 60kN/m2. What is the ultimate bearing capacity for a strip footing of 1.2 m width to be placed on the surface of the same soil?

A reinforced concrete circular pile of 12 m length and 0.6 m diameter is embedded in stiff clay which has an undrained unit cohesion of 110 kN/m2. The adhesion factor is 0.5. The Net ultimate Pullout (Uplift) Load for the pile (in kN, round off to 1 decimal place) is 1244.07

A point load of 650 kN is applied on the surface of a thick layer of clay. Using Boussinesq's elastic analysis, what is approximate value of the estimated vertical stress at a depth 2 m and a radial distance of 1.0 m from the point of application of load?

A soil profile above the rock surface for a 30∘ infinite slope is shown in the figure where Su is the undrained shear strength and γt is unit weight. The slip will occur at a depth of (assume ϕ=0)

A strip footing is resting on the ground surface of a pure clay bed having an undrained cohesion Cu. The ultimate bearing capacity of the footing is equal to

The infinite sand slope shown in the figure is on the verge of sliding failure. The ground water table coincides with ground surface. The value of effective angle of internal friction (in degrees, correct upto one decimal place) of sand is ?.(Take γw=10kN/m3)

A rectangular footing L×B is to be placed at a depth D below ground level such that DB<2.5 . The factor Nc to be used in deciding of the allowable bearing capacity for the footing as given by Skempton is calculated using the equation (where, NCR=NC for rectangular footing, NCS=NC at surface )