87 + Interview Questions in Soil Mechanics Page 1 InterviewSolution

1.	Which one of the following statements regarding coefficient of consolidation Cv is correct?
Answer» Which one of the following statements regarding coefficient of consolidation $C_{v}$ is correct?

Discussion

2.	In an unconfined compression test on stiff clay, if the failure plane made an angle of 52o to the horizontal, what would be the angle of shearing resistance?
Answer» In an unconfined compression test on stiff clay, if the failure plane made an angle of $52^{o}$ to the horizontal, what would be the angle of shearing resistance?

Discussion

3.	Which one of the following pairs of parameters and expression is NOT correctly matched?
Answer» Which one of the following pairs of parameters and expression is NOT correctly matched?

Discussion

4.	The flow net constructed for a dam is shown in the figure below. Taking coefficient of permeability as 3.8×10−6 m/s, the quantity of flow (in cm3/sec) under the dam per m is7.182
Answer» The flow net constructed for a dam is shown in the figure below. Taking coefficient of permeability as $3.8 \times 10^{- 6} m / s$ , the quantity of flow $(i n c m^{3} / s e c)$ under the dam per m is 7.182

4.

The flow net constructed for a dam is shown in the figure below. Taking coefficient of permeability as 3.8×10−6 m/s, the quantity of flow (in cm3/sec) under the dam per m is7.182

Answer»

The flow net constructed for a dam is shown in the figure below. Taking coefficient of permeability as $3.8 \times 10^{- 6} m / s$ , the quantity of flow $(i n c m^{3} / s e c)$ under the dam per m is

7.182

Discussion

5.	In a compaction test, G, w, S and e represent the specific gravity, water content, degree of saturation and void ratio of the soil sample, respectively. If γw represents the unit weight of water and γd represents the dry unit weight of the soil, the equation for zero air voids line is
Answer» In a compaction test, G, w, S and e represent the specific gravity, water content, degree of saturation and void ratio of the soil sample, respectively. If $γ_{w}$ represents the unit weight of water and $γ_{d}$ represents the dry unit weight of the soil, the equation for zero air voids line is

Discussion

6.	In a direct shear test, the shear stress and normal stress on a dry sand sample at failure are 0.6 kg/cm2 and 1 kg/cm2 respectively. The angle of internal friction of the sand will be nearly.
Answer» In a direct shear test, the shear stress and normal stress on a dry sand sample at failure are $0.6 k g / c m^{2}$ and $1 k g / c m^{2}$ respectively. The angle of internal friction of the sand will be nearly.

Discussion

7.	When an unconfined compression test is conducted on a cylinder of soil, it fails under axial stress of 1.2kg/cm2. The failure plane makes an angle of 50∘ with the horizontal. Determine the cohesion of the soil0.503
Answer» When an unconfined compression test is conducted on a cylinder of soil, it fails under axial stress of $1.2 k g / c m^{2}$ . The failure plane makes an angle of $50^{\circ}$ with the horizontal. Determine the cohesion of the soil 0.503

Discussion

8.	The total horizontal and Vertical stresses at a point X in a saturated sandy medium are 170 kPa and 300 kPa, respectively. The static pore- water pressure is 30 kPa. At failure, the excess pore-water pressure is measured to be 94.50 kPa and the shear stresses on the vertical and horizontal planes passing through the point X and zero. Effective cohesion is 0 kPa and effective angle of internal friction is 36∘. The shear strength (kPa, up to two decimal places) at point X is 52.52
Answer» The total horizontal and Vertical stresses at a point X in a saturated sandy medium are 170 kPa and 300 kPa, respectively. The static pore- water pressure is 30 kPa. At failure, the excess pore-water pressure is measured to be 94.50 kPa and the shear stresses on the vertical and horizontal planes passing through the point X and zero. Effective cohesion is 0 kPa and effective angle of internal friction is $36^{\circ}$ . The shear strength (kPa, up to two decimal places) at point X is 52.52

Discussion

9.	At a site where sand deposit extends to a great depth, the ground water table is lowered from 2 m below G.L to 3 m below the G.L. The increase in effective stress is(γd=16 kN/m3 and γ′=10 kN/m3)
Answer» At a site where sand deposit extends to a great depth, the ground water table is lowered from 2 m below G.L to 3 m below the G.L. The increase in effective stress is $(γ_{d} = 16 k N / m^{3} a n d γ^{'} = 10 k N / m^{3})$

Discussion

10.

Match List-I (Investigator) with List-II (Equation) and select the correct answer using the codes given below the lists: List - IList - IIA. Skempton1. v=kiB. Coulomb2. σ1=σ−uC. Stokes3. v=D2(γs−γw)18ηD. Terzaghi4. s=c+σ tan Φ 5. u=B[σ3+A(σ1−σ3)]CodesA B C D

Answer»

Match List-I (Investigator) with List-II (Equation) and select the correct answer using the codes given below the lists:

List - I	List - II
A. Skempton	1. $v = k i$
B. Coulomb	2. $σ_{1} = σ - u$
C. Stokes	3. $v = \frac{D^{2} (γ_{s} - γ_{w})}{18 η}$
D. Terzaghi	4. $s = c + σ t a n Φ$
	5. $u = B [σ_{3} + A (σ_{1} - σ_{3})]$

Codes

A B C D

Discussion

11.	A homogeneous earth dam is 43 m high with 3 m as free board and a 30 m long horizontal filter at the downstream end. The flownet drawn in the dam section consists of 5 flow channels and 15 potential drops. If the dam is 500 m long and the permeability of the material of the dam is uniformly 3×10−3 m/s, the total discharge permeating through the body of the dam will be
Answer» A homogeneous earth dam is 43 m high with 3 m as free board and a 30 m long horizontal filter at the downstream end. The flownet drawn in the dam section consists of 5 flow channels and 15 potential drops. If the dam is 500 m long and the permeability of the material of the dam is uniformly $3 \times 10^{- 3}$ m/s, the total discharge permeating through the body of the dam will be

Discussion

12.	In a triaxial compression test, the major principal stress was 90 kPa and the minor principal stress was 30 kPa, at failure. The pore pressure at failure was observed to be 10 kPa. The tangent of the angle of shearing resistance of the sandy soil that was tested was
Answer» In a triaxial compression test, the major principal stress was $90 k P a$ and the minor principal stress was $30 k P a$ , at failure. The pore pressure at failure was observed to be $10 k P a$ . The tangent of the angle of shearing resistance of the sandy soil that was tested was

Discussion

13.	Constant head permeability tests were performed on two soil specimens, S1 and S2. The ratio of height of the two (LS1:LS2) is 1.5, the ratio of the diameter of specimens (DS1:DS2) is 0.5, and the ratio of the constant head (hS1:hS2) applied on the specimens is 2.0. If the discharge from both the specimens is equal, the ratio of the permeability of the soil specimens (kS1:kS2) is 3
Answer» Constant head permeability tests were performed on two soil specimens, S1 and S2. The ratio of height of the two $(L_{S 1} : L_{S 2})$ is 1.5, the ratio of the diameter of specimens $(D_{S 1} : D_{S 2})$ is 0.5, and the ratio of the constant head $(h_{S 1} : h_{S 2})$ applied on the specimens is 2.0. If the discharge from both the specimens is equal, the ratio of the permeability of the soil specimens $(k_{S 1} : k_{S 2})$ is 3

Discussion

14.	Consolidation test was conducted on two soils A and B respectively. The soil A is 1.5 times more compressible than soil B. The thickness of A was 2 times that of B. If the time required for 50% consolidation was three times longer for soil A than for soil B, the ratio of coefficient of permeability of A to that of B is ?
Answer» Consolidation test was conducted on two soils A and B respectively. The soil A is 1.5 times more compressible than soil B. The thickness of A was 2 times that of B. If the time required for 50% consolidation was three times longer for soil A than for soil B, the ratio of coefficient of permeability of A to that of B is ?

Discussion

15.	A certain soil has the following properties, Gs=2.71,n=40% and w=20% .The degree of saturation of the soil rounded off to the nearest percentage is _______ .81
Answer» A certain soil has the following properties, $G_{s} = 2.71, n = 40$ % and $w = 20$ % .The degree of saturation of the soil rounded off to the nearest percentage is _______ . 81

Discussion

16.	At a point through cross section in a mass of saturated and homogenous soil, seeping water follows a path inclined at 10∘ below to the horizontal. The hydraulic gradient is 0.5, void ratio and specific gravity of grains are 0.9 and 2.75 respectively. The resultant body force per unit volume of cylinder soil element is (γw=10kN/m3)
Answer» At a point through cross section in a mass of saturated and homogenous soil, seeping water follows a path inclined at $10^{\circ}$ below to the horizontal. The hydraulic gradient is 0.5, void ratio and specific gravity of grains are 0.9 and 2.75 respectively. The resultant body force per unit volume of cylinder soil element is $(γ_{w} = 10 k N / m^{3})$

Discussion

17.	A 10 m thick clay layer is resting over a 3 m thick sand layer and is submerged. A fill of 2 m thick sand with unit weight of 20kN/m3 is placed above the clay layer to accelerate the rate of consolidation of the clay layer. Coefficient of consolidation of clay is 9×10−2m2/year and coefficient of volume compressibility of clay is 2.2×10−4m2/kN. Assume Taylor's relations between time factor and average degree of consolidation.The settlement (in mm, round off to two decimal places) of the clay layer, 10 years after the construction of the fill, is 18.83
Answer» A 10 m thick clay layer is resting over a 3 m thick sand layer and is submerged. A fill of 2 m thick sand with unit weight of 20 $k N / m^{3}$ is placed above the clay layer to accelerate the rate of consolidation of the clay layer. Coefficient of consolidation of clay is $9 \times 10^{- 2} m^{2} / y e a r$ and coefficient of volume compressibility of clay is $2.2 \times 10^{- 4} m^{2} / k N$ . Assume Taylor's relations between time factor and average degree of consolidation. The settlement (in mm, round off to two decimal places) of the clay layer, 10 years after the construction of the fill, is 18.83

Discussion

18.	In an undrained triaxial test on a saturated clay, the Poisson's ratio is
Answer» In an undrained triaxial test on a saturated clay, the Poisson's ratio is

Discussion

19.	A 1.25 m layer of soil (n = 0.35, G = 2.65) is subjected to an upward seepage head of 1.85 m. What depth of coarse sand would be required above the existing soil to provide a factor of safety of 2 against piping? Assume that coarse sand has the same porosity and specific gravity as the soil and that there is negligible head loss in sand Take γw=9.81 kN/m3. 2.2
Answer» A 1.25 m layer of soil (n = 0.35, G = 2.65) is subjected to an upward seepage head of 1.85 m. What depth of coarse sand would be required above the existing soil to provide a factor of safety of 2 against piping? Assume that coarse sand has the same porosity and specific gravity as the soil and that there is negligible head loss in sand Take $γ_{w} = 9.81 k N / m^{3}$ . 2.2

Discussion

20.	Water is flowing at a steady rate through a homogeneous and saturated horizontal soil strip of 10 m length. The strip is being subjected to a constant water head of 5 m at the beginning and 1 m at the end. If the governing equation of flow in the soil is d2H/dx2=0 (x = distance along the soil strip) value of H (in m) at the middle of the strip is 3
Answer» Water is flowing at a steady rate through a homogeneous and saturated horizontal soil strip of 10 m length. The strip is being subjected to a constant water head of 5 m at the beginning and 1 m at the end. If the governing equation of flow in the soil is $d^{2} H / d x^{2} = 0$ (x = distance along the soil strip) value of H (in m) at the middle of the strip is 3

Discussion

21.	In a triaxial test at failure, major principal stress was 180 kPa, minor principal stress was 100 kPa, and pore pressure was 20 kPa. The tangent of the angle of shearing resistance of the sandy soil tested is
Answer» In a triaxial test at failure, major principal stress was 180 kPa, minor principal stress was 100 kPa, and pore pressure was 20 kPa. The tangent of the angle of shearing resistance of the sandy soil tested is

Discussion

22.	A clay soil specimen when tested in unconfined condition gave an unconfined compressive strength of 100 kN/m2. A specimen of the same clay with the same initial condition is subjected to a UU triaxial test under a cell pressure of 100 kN/m2. Axial stress (in kN/m2) at failure would be
Answer» A clay soil specimen when tested in unconfined condition gave an unconfined compressive strength of $100 k N / m^{2}$ . A specimen of the same clay with the same initial condition is subjected to a $U U$ triaxial test under a cell pressure of $100 k N / m^{2}$ . Axial stress $($ in $k N / m^{2})$ at failure would be

Discussion

23.	A soil has discharge velocity of 5×10−7 m/s and a void ratio of 0.50. Its seepage velocity will be
Answer» A soil has discharge velocity of $5 \times 10^{- 7}$ m/s and a void ratio of 0.50. Its seepage velocity will be

Discussion

24.	In a deposit of silt, the water table originally at a depth of 1 m below ground level was lowered to 3 m below ground level and got capillary saturated. The saturated unit weight of soil is 20kN/m3. The change in effective pressure at a depth of 2 m is (Assume γw=10kN/m3)
Answer» In a deposit of silt, the water table originally at a depth of 1 m below ground level was lowered to 3 m below ground level and got capillary saturated. The saturated unit weight of soil is $20 k N / m^{3} .$ The change in effective pressure at a depth of 2 m is $(A s s u m e γ_{w} = 10 k N / m^{3})$

Discussion

25.	An upward hydraulic gradient i of a certain magnitude will initiate the phenomenon of boiling in granular soils. The magnitude of this gradient is
Answer» An upward hydraulic gradient i of a certain magnitude will initiate the phenomenon of boiling in granular soils. The magnitude of this gradient is

Discussion

26.	In a soil specimen, the total stress, effective stress, hydraulic gradient and critical hydraulic gradient are σ,σ′, i and ic respectively. For initiation of quick sand condition, which one of the following statement is TRUE?
Answer» In a soil specimen, the total stress, effective stress, hydraulic gradient and critical hydraulic gradient are $σ, σ^{'},$ $i$ and $i_{c}$ respectively. For initiation of quick sand condition, which one of the following statement is TRUE?

Discussion

27.	A consolidation undrained (CU) triaxial compression test is conducted on a normally consolidated clay at a confining pressure of 100 kPa. The deviator stress at failure is 80 kPa, and the pore-water pressure measured at failure is 50 kPa. The effective angle of internal friction (in degrees, up to one decimal place) of the soil is 26.38
Answer» A consolidation undrained (CU) triaxial compression test is conducted on a normally consolidated clay at a confining pressure of 100 kPa. The deviator stress at failure is 80 kPa, and the pore-water pressure measured at failure is 50 kPa. The effective angle of internal friction (in degrees, up to one decimal place) of the soil is 26.38

Discussion

28.	In a drained triaxial compression test, a saturated specimen of a cohesionless sand fails under a deviator stress of 3kgf/cm2 when the cell pressure is 1kgf/cm2. The effective angle of shearing resistance of sand is about
Answer» In a drained triaxial compression test, a saturated specimen of a cohesionless sand fails under a deviator stress of $3 k g f / c m^{2}$ when the cell pressure is $1 k g f / c m^{2}$ . The effective angle of shearing resistance of sand is about

Discussion

29.	Which one of the following phase diagrams represents a clay at its shrinkage limit?
Answer» Which one of the following phase diagrams represents a clay at its shrinkage limit?

Discussion

30.	In the phase diagrams given the change due to initial state changing into final state is shown due to consolidation. Depth of soil layer undergoing consolidation is H, e0 is initial void ratio; ef is final void ratio; Δe is change in void ratio.Indicate which of the following expressions gives settlement of the layer
Answer» In the phase diagrams given the change due to initial state changing into final state is shown due to consolidation. Depth of soil layer undergoing consolidation is H, $e_{0}$ is initial void ratio; $e_{f}$ is final void ratio; $Δ e$ is change in void ratio. Indicate which of the following expressions gives settlement of the layer

Discussion

31.	Consider a two-dimensional flow through isotropic soil along x-direction and z-direction. If h is the hydraulic head, the Laplace's equation of continuity is expressed as
Answer» Consider a two-dimensional flow through isotropic soil along x-direction and z-direction. If h is the hydraulic head, the Laplace's equation of continuity is expressed as

Discussion

32.	A saturated undisturbed sample from a clay strata has moisture content of 22.22% and specific weight of 2.7. Assuming γw=10kN/m3, the void ratio and the saturated unit weight of the clay, respectively are
Answer» A saturated undisturbed sample from a clay strata has moisture content of 22.22% and specific weight of 2.7. Assuming $γ_{w} = 10 k N / m^{3}$ , the void ratio and the saturated unit weight of the clay, respectively are

Discussion

33.	A 20 m thick clay layer is sandwiched between a silty sand layer and a gravelly sand layer. The layer experiences 30 mm settlement in 2 years.Given :TV=⎧⎪⎪⎨⎪⎪⎩π4(U100)2 for U≤60∘/∘1.784−0.933 log10(100−U)U>60∘/∘Where TV is the time factor and U is the degree of consolidation in %If the coefficient of consolidation of the layer is 0.003 cm2/s, the deposit will experience a total of 50 mm settlement in the next _____ years.4.43
Answer» A 20 m thick clay layer is sandwiched between a silty sand layer and a gravelly sand layer. The layer experiences 30 mm settlement in 2 years. Given : $T_{V} = ⎧ ⎪⎪ ⎨ ⎪⎪ ⎩ \begin{matrix} \frac{π}{4} {(\frac{U}{100})}^{2} & f o r U \leq 60^{\circ /_{\circ}} 1.784 - 0.933 l o g_{10} (100 - U) & U > 60^{\circ /_{\circ}} \end{matrix}$ Where $T_{V}$ is the time factor and U is the degree of consolidation in % If the coefficient of consolidation of the layer is $0.003 c m^{2} / s$ , the deposit will experience a total of 50 mm settlement in the next _____ years. 4.43

Discussion

34.	Construction of a new building founded on a clayey soil was completed in January 2010. In January 2014, the average consolidation settlement of the foundation in clay was recorded as 10 mm. The ultimate consolidation settlement was estimated in design as 40 mm. Considering double drainage to occur at the clayey soil site, the expected consolidation settlement in January 2019 (in mm, round off to the nearest integer) will be 15
Answer» Construction of a new building founded on a clayey soil was completed in January 2010. In January 2014, the average consolidation settlement of the foundation in clay was recorded as 10 mm. The ultimate consolidation settlement was estimated in design as 40 mm. Considering double drainage to occur at the clayey soil site, the expected consolidation settlement in January 2019 (in mm, round off to the nearest integer) will be 15

Discussion

35.	A soil fails under an axial vertical stress of 100 kN/m2 in unconfined compression test. The failure plane makes an angle of 50° with the horizontal. The shear parameters ′c′ and ′Φ′ respectively will be
Answer» A soil fails under an axial vertical stress of $100 k N / m^{2}$ in unconfined compression test. The failure plane makes an angle of $50 °$ with the horizontal. The shear parameters $^{'} c^{'}$ and $^{'} Φ^{'}$ respectively will be

Discussion

36.	A 3m×3m square precast reinforced concrete segments to be installed by pushing them through an existing railway embankment for making an underpass as shown in the figure. A reaction arrangement using precast PCC blocks placed on the ground is to be made for the jacks.At each stage, the jacks are required to apply a force of 1875 kN to push the segment. The jacks will react against the rigid steel plate placed against the reaction arrangement. The footprint area of reaction arrangement on natural ground is 37.5m2. The unit weight of PCC block is 24 kN/m3. The properties of the natural ground are: c = 17 kPa; ϕ=25∘ and γ=18kN/m3 . Assuming that the reaction arrangement has rough interface and has the same properties that of soil, the factor of safety (round off to 1 decimal place) against shear failure is 2.0187
Answer» A $3 m \times 3 m$ square precast reinforced concrete segments to be installed by pushing them through an existing railway embankment for making an underpass as shown in the figure. A reaction arrangement using precast PCC blocks placed on the ground is to be made for the jacks. At each stage, the jacks are required to apply a force of 1875 kN to push the segment. The jacks will react against the rigid steel plate placed against the reaction arrangement. The footprint area of reaction arrangement on natural ground is 37.5 $m^{2}$ . The unit weight of PCC block is 24 $k N / m^{3}$ . The properties of the natural ground are: c = 17 kPa; $ϕ = 25^{\circ}$ and $γ = 18 k N / m^{3}$ . Assuming that the reaction arrangement has rough interface and has the same properties that of soil, the factor of safety (round off to 1 decimal place) against shear failure is 2.0187

Discussion

37.	A seepage flow condition is shown in the figure. The saturated unit weight of the soil γsat=18 kN/m3. Using unit weight of water, γw=9.81 kN/m3, the effective vertical stress (expressed in kN/m2) on plane X-X is 65.475
Answer» A seepage flow condition is shown in the figure. The saturated unit weight of the soil $γ_{s a t} = 18 k N / m^{3}$ . Using unit weight of water, $γ_{w} = 9.81 k N / m^{3}$ , the effective vertical stress (expressed in $k N / m^{2}$ ) on plane X-X is 65.475

Discussion

38.	To make certain that the backfill material is more pervious than the soil to be drained, the relationship used is
Answer» To make certain that the backfill material is more pervious than the soil to be drained, the relationship used is

Discussion

39.	A silty-clay deposit 4 m thick lies between two layers of sand as shown below. If the coefficient of permeability of clay is 1×10−6cm/sec then the seepage through the clay is
Answer» A silty-clay deposit 4 m thick lies between two layers of sand as shown below. If the coefficient of permeability of clay is $1 \times 10^{- 6} c m / s e c$ then the seepage through the clay is

Discussion

40.	A deposit of fine sand has a porosity n and specific gravity of soil solids is G. The hydraulic gradient of the deposit to develop boiling condition of sand is given by
Answer» A deposit of fine sand has a porosity n and specific gravity of soil solids is G. The hydraulic gradient of the deposit to develop boiling condition of sand is given by

Discussion

41.	A laboratory vane shear test apparatus is used to determine the shear strength of a clay sample and only one end of the vane takes part in shearing the soil. If T= applied torque, H= height of vane and D= diameter of the vane, then shear strength of the clay is given by
Answer» A laboratory vane shear test apparatus is used to determine the shear strength of a clay sample and only one end of the vane takes part in shearing the soil. If $T =$ applied torque, $H =$ height of vane and $D =$ diameter of the vane, then shear strength of the clay is given by

Discussion

42.	A river 5m deep consists of a sand bed with saturated unit weight of 20kN/m3, γw=9.81kN/m3. The effective vertical stress at 5 m from the top of sand bed is
Answer» A river 5m deep consists of a sand bed with saturated unit weight of $20 k N / m^{3}$ , $γ_{w} = 9.81 k N / m^{3}$ . The effective vertical stress at 5 m from the top of sand bed is

Discussion

43.	The result of a ¯¯¯¯¯¯¯¯CU test on a compacted soil are given below:Sample noσ3σ1−σ3U(kN/m2)(kN/m2)(kN/m2)170230−202350550+90The cohesion intercept in (in kN/m2) and the angle of shearing resistance (in degree) in terms of effective stresses respectively are
Answer» The result of a $¯ ¯¯¯¯¯¯ ¯ C U$ test on a compacted soil are given below: $\begin{matrix} Sample no & σ_{3} & σ_{1} - σ_{3} & U (k N / m^{2}) & (k N / m^{2}) & (k N / m^{2}) 1 & 70 & 230 & - 20 2 & 350 & 550 & + 90 \end{matrix}$ The cohesion intercept in (in $k N / m^{2}$ ) and the angle of shearing resistance (in degree) in terms of effective stresses respectively are

Discussion

44.	A water tank is to be constructed on the soil deposit shown in the figure below. A circular footing of diameter 3 m and depth of embankment 1 m has been designed to support the tank. The total vertical load to be taken by the footing is 1500 kN. Assume the unit weight of water as 10kN/m3 and the load dispersion pattern as 2V:1H. The expected settlement of the tank due to primary consolidation of the clay layer in _____ mm.53.236
Answer» A water tank is to be constructed on the soil deposit shown in the figure below. A circular footing of diameter 3 m and depth of embankment 1 m has been designed to support the tank. The total vertical load to be taken by the footing is 1500 kN. Assume the unit weight of water as 10 $k N / m^{3}$ and the load dispersion pattern as 2V:1H. The expected settlement of the tank due to primary consolidation of the clay layer in _____ mm. 53.236

Discussion

45.	In a shrinkage limit test, the volume and mass of a dry soil pit are found to be 50cm3 and 88 g respectively. The specific gravity of the soil solids is 2.71 and the density of water is 1 g/cc. The shrinkage limit (in % up to two decimal places) is 19.91
Answer» In a shrinkage limit test, the volume and mass of a dry soil pit are found to be 50 $c m^{3}$ and 88 g respectively. The specific gravity of the soil solids is 2.71 and the density of water is 1 g/cc. The shrinkage limit (in % up to two decimal places) is 19.91

Discussion

46.	A homogeneous anisotropic earth dam which is 20 m high, is constructed on an impermeable foundation. The coefficients of permeability of the soil used for the construction of the dam, in the horizontal and vertical directions are 4.8 × 10−8m/s and 1.6 × 10−8m/s respectively. The water level on the reservoir side is at 18m from the base of the dam; downstream side is dry. It is seen that there are 4 flow channels and 18 equipotential drops in a square flow net drawn in the transformed dam section. The quantity of seepage per unit length is _____ × 10−8 m3/s/m through the dam.11.08
Answer» A homogeneous anisotropic earth dam which is 20 m high, is constructed on an impermeable foundation. The coefficients of permeability of the soil used for the construction of the dam, in the horizontal and vertical directions are 4.8 $\times$ $10^{- 8} m / s$ and 1.6 $\times$ $10^{- 8} m / s$ respectively. The water level on the reservoir side is at 18m from the base of the dam; downstream side is dry. It is seen that there are 4 flow channels and 18 equipotential drops in a square flow net drawn in the transformed dam section. The quantity of seepage per unit length is _____ $\times$ $10^{- 8}$ $m^{3} / s / m$ through the dam. 11.08

Discussion

47.	A one-dimensional consolidation test is carried out on a standard 19 mm thick clay sample. The oedometer's deflection gauge indicates a reading of 2.1 mm, just before removal of the load, without allowing any swelling. The void ratio is 0.62 at this stage. The initial void ratio (round off to two decimal places) of the standard specimen is 0.82
Answer» A one-dimensional consolidation test is carried out on a standard 19 mm thick clay sample. The oedometer's deflection gauge indicates a reading of 2.1 mm, just before removal of the load, without allowing any swelling. The void ratio is 0.62 at this stage. The initial void ratio (round off to two decimal places) of the standard specimen is 0.82

Discussion

48.	In a falling head permeameter test on a silty clay sample, the following results were obtained;sample length 120mm; sample diameter 80mm; initial head 1200mm; final head 400mm; time for fall in head 6 minutes stand pipe diameter 4mm. The coefficient of permeability of the soil is_____ ×10−4 mm/sec9.155
Answer» In a falling head permeameter test on a silty clay sample, the following results were obtained; sample length 120mm; sample diameter 80mm; initial head $1200 m m$ ; final head $400 m m$ ; time for fall in head $6$ minutes stand pipe diameter $4 m m$ . The coefficient of permeability of the soil is_____ $\times 10^{- 4}$ mm/sec 9.155

48.

In a falling head permeameter test on a silty clay sample, the following results were obtained;sample length 120mm; sample diameter 80mm; initial head 1200mm; final head 400mm; time for fall in head 6 minutes stand pipe diameter 4mm. The coefficient of permeability of the soil is_____ ×10−4 mm/sec9.155

Answer»

In a falling head permeameter test on a silty clay sample, the following results were obtained;

sample length 120mm; sample diameter 80mm; initial head $1200 m m$ ; final head $400 m m$ ; time for fall in head $6$ minutes stand pipe diameter $4 m m$ . The coefficient of permeability of the soil is_____ $\times 10^{- 4}$ mm/sec

9.155

Discussion

49.	A flownet constructed to determine the seepage through an earth dam which is homogeneous but anisotropic, gave four flow channels and sixteen equipotential drops. The coefficients of permeability in the horizontal and vertical directions are 4.0×10−7m/sand1×10−7m/s respectively. If the storage head was 20 m, then the seepage per unit length of the dam (in m3/s) would be
Answer» A flownet constructed to determine the seepage through an earth dam which is homogeneous but anisotropic, gave four flow channels and sixteen equipotential drops. The coefficients of permeability in the horizontal and vertical directions are $4.0 \times 10^{- 7} m / s a n d 1 \times 10^{- 7} m / s$ respectively. If the storage head was 20 m, then the seepage per unit length of the dam (in m3/s) would be

Discussion

50.	A flownet of a coffer dam foundation has 6 flow channels and 18 equipotential drops. The head of water lost during seepage is 6 m. If the coefficient of permeability of foundation is 4×10−5 m/min, then the seepage loss per metre length of dam will be
Answer» A flownet of a coffer dam foundation has 6 flow channels and 18 equipotential drops. The head of water lost during seepage is 6 m. If the coefficient of permeability of foundation is $4 \times 10^{- 5}$ m/min, then the seepage loss per metre length of dam will be

Discussion

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Which one of the following statements regarding coefficient of consolidation Cv is correct?

In an unconfined compression test on stiff clay, if the failure plane made an angle of 52o to the horizontal, what would be the angle of shearing resistance?

Which one of the following pairs of parameters and expression is NOT correctly matched?

The flow net constructed for a dam is shown in the figure below. Taking coefficient of permeability as 3.8×10−6 m/s, the quantity of flow (in cm3/sec) under the dam per m is7.182

In a compaction test, G, w, S and e represent the specific gravity, water content, degree of saturation and void ratio of the soil sample, respectively. If γw represents the unit weight of water and γd represents the dry unit weight of the soil, the equation for zero air voids line is

In a direct shear test, the shear stress and normal stress on a dry sand sample at failure are 0.6 kg/cm2 and 1 kg/cm2 respectively. The angle of internal friction of the sand will be nearly.

When an unconfined compression test is conducted on a cylinder of soil, it fails under axial stress of 1.2kg/cm2. The failure plane makes an angle of 50∘ with the horizontal. Determine the cohesion of the soil0.503

At a site where sand deposit extends to a great depth, the ground water table is lowered from 2 m below G.L to 3 m below the G.L. The increase in effective stress is(γd=16 kN/m3 and γ′=10 kN/m3)

Match List-I (Investigator) with List-II (Equation) and select the correct answer using the codes given below the lists: List - IList - IIA. Skempton1. v=kiB. Coulomb2. σ1=σ−uC. Stokes3. v=D2(γs−γw)18ηD. Terzaghi4. s=c+σ tan Φ 5. u=B[σ3+A(σ1−σ3)]CodesA B C D

In a triaxial compression test, the major principal stress was 90 kPa and the minor principal stress was 30 kPa, at failure. The pore pressure at failure was observed to be 10 kPa. The tangent of the angle of shearing resistance of the sandy soil that was tested was

A certain soil has the following properties, Gs=2.71,n=40% and w=20% .The degree of saturation of the soil rounded off to the nearest percentage is _______ .81

In an undrained triaxial test on a saturated clay, the Poisson's ratio is

In a triaxial test at failure, major principal stress was 180 kPa, minor principal stress was 100 kPa, and pore pressure was 20 kPa. The tangent of the angle of shearing resistance of the sandy soil tested is

A clay soil specimen when tested in unconfined condition gave an unconfined compressive strength of 100 kN/m2. A specimen of the same clay with the same initial condition is subjected to a UU triaxial test under a cell pressure of 100 kN/m2. Axial stress (in kN/m2) at failure would be

A soil has discharge velocity of 5×10−7 m/s and a void ratio of 0.50. Its seepage velocity will be

In a deposit of silt, the water table originally at a depth of 1 m below ground level was lowered to 3 m below ground level and got capillary saturated. The saturated unit weight of soil is 20kN/m3. The change in effective pressure at a depth of 2 m is (Assume γw=10kN/m3)

An upward hydraulic gradient i of a certain magnitude will initiate the phenomenon of boiling in granular soils. The magnitude of this gradient is

In a soil specimen, the total stress, effective stress, hydraulic gradient and critical hydraulic gradient are σ,σ′, i and ic respectively. For initiation of quick sand condition, which one of the following statement is TRUE?

In a drained triaxial compression test, a saturated specimen of a cohesionless sand fails under a deviator stress of 3kgf/cm2 when the cell pressure is 1kgf/cm2. The effective angle of shearing resistance of sand is about

Which one of the following phase diagrams represents a clay at its shrinkage limit?

Consider a two-dimensional flow through isotropic soil along x-direction and z-direction. If h is the hydraulic head, the Laplace's equation of continuity is expressed as

A saturated undisturbed sample from a clay strata has moisture content of 22.22% and specific weight of 2.7. Assuming γw=10kN/m3, the void ratio and the saturated unit weight of the clay, respectively are

A soil fails under an axial vertical stress of 100 kN/m2 in unconfined compression test. The failure plane makes an angle of 50° with the horizontal. The shear parameters ′c′ and ′Φ′ respectively will be

A seepage flow condition is shown in the figure. The saturated unit weight of the soil γsat=18 kN/m3. Using unit weight of water, γw=9.81 kN/m3, the effective vertical stress (expressed in kN/m2) on plane X-X is 65.475

To make certain that the backfill material is more pervious than the soil to be drained, the relationship used is

A silty-clay deposit 4 m thick lies between two layers of sand as shown below. If the coefficient of permeability of clay is 1×10−6cm/sec then the seepage through the clay is

A deposit of fine sand has a porosity n and specific gravity of soil solids is G. The hydraulic gradient of the deposit to develop boiling condition of sand is given by

A laboratory vane shear test apparatus is used to determine the shear strength of a clay sample and only one end of the vane takes part in shearing the soil. If T= applied torque, H= height of vane and D= diameter of the vane, then shear strength of the clay is given by

A river 5m deep consists of a sand bed with saturated unit weight of 20kN/m3, γw=9.81kN/m3. The effective vertical stress at 5 m from the top of sand bed is

The result of a ¯¯¯¯¯¯¯¯CU test on a compacted soil are given below:Sample noσ3σ1−σ3U(kN/m2)(kN/m2)(kN/m2)170230−202350550+90The cohesion intercept in (in kN/m2) and the angle of shearing resistance (in degree) in terms of effective stresses respectively are

In a shrinkage limit test, the volume and mass of a dry soil pit are found to be 50cm3 and 88 g respectively. The specific gravity of the soil solids is 2.71 and the density of water is 1 g/cc. The shrinkage limit (in % up to two decimal places) is 19.91

A flownet of a coffer dam foundation has 6 flow channels and 18 equipotential drops. The head of water lost during seepage is 6 m. If the coefficient of permeability of foundation is 4×10−5 m/min, then the seepage loss per metre length of dam will be