# GATE Questions & Answers of Seepage through soils - two-dimensional flow

## What is the Weightage of Seepage through soils - two-dimensional flow in GATE Exam?

Total 24 Questions have been asked from Seepage through soils - two-dimensional flow topic of Soil Mechanics subject in previous GATE papers. Average marks 1.79.

At a construction site, a contractor plans to make an excavation as shown in the figure.

The water level in the adjacent river is at an elevation of +20.0 m. Unit weight of water is 10 kN/m3. The factor of safety (up to two decimal places) against sand boiling  for the proposed excavation is ______

Consider the following statement related to the pore pressure parameters, A and B:

P. A always lies between 0 and 1.0

Q. A can be less than 0 or greater than 1.0

R. B always lies between 0 and 1.0

S. B can be less than 0 or grater than 1.0

For these statements, which one of the following options is correct?

A sheet pile has an embedment depth of 12 m in a homogeneous soil stratum. The coefficient of permeabilty of soil is 10-6 m/s. Diffrence in the water levels between the sides of the sheet pile is 4 m. The flow net is constructed with five number of flow lines and eleven number of equipotential lines. The quantity of seepage (in cm3/s per m, up to one decimal place) under the sheet pile is___________

A seepage flow condition is shown in the figure. The saturated unit weight of the soil ${\gamma }_{sat=18}$ kN/m3. Using unit weight of water,${\gamma }_{w=9.81}$ kN/m3, the effective vertical stress (expressed in kN/m2) on plane X-X is ________

Seepage is occurring through a porous media shown in the figure. The hydraulic conductivity values (k1, k2, k3) are in m/day.

The seepage discharge (m3/day per m) through the porous media at section PQ is

The seepage occurring through an earthen dam is represented by a flownet comprising of 10 equipotential drops and 20 flow channels. The coefficient of permeability of the soil is 3 mm/min and the head loss is 5 m. The rate of seepage (expressed in cm3/s per m length of the dam) through the earthen dam is _________

Which of the following statements is TRUE for the relation between discharge velocity and seepage velocity ?

A non-homogeneous soil deposit consists of a silt layer sandwiched between a fine-sand layer at top and a clay layer below. Permeability of the silt layer is 10 times the permeability of the clay layer and one-tenth of the permeability of the sand layer. Thickness of the silt layer is 2 times the thickness of the sand layer and two-third of the thickness of the clay layer. The ratio of equivalent horizontal and equivalent vertical permeability of the deposit is ________.

Laplace equation for water flow in soils is given below.

$\frac{{\mathrm{\partial }}^{2}H}{\mathrm{\partial }{x}^{2}}+\frac{{\mathrm{\partial }}^{2}H}{\mathrm{\partial }{y}^{2}}+\frac{{\mathrm{\partial }}^{2}H}{\mathrm{\partial }{z}^{2}}=0$

Head H does not vary in y and z directions.
Boundary conditions are: at x = 0, H = 5;and $\frac{dH}{dx}=-1$

What is the value of H at x = 1.2? __________

The soil profile below a lake with water level at elevation = 0m and lake bottom at elevation = -10m is shown in the figure, where k is the permeability coefficient. A piezometer (stand pipe) installed in the sand layer shows a reading of +10 m elevation. Assume that thepiezometric headis uniform in the sand layer. The quantity of water (in m3/s) flowing into the lake from the sand layer through the silt layer per unit area of the lake bed is:

Two soil specimens with identical geometric dimensions were subjected to falling head permeability tests in the laboratory under identical conditions. The fall of water head was measured after an identical time interval. The ratio of initial to final water heads for the test involving the first specimen was 1.25. If the coefficient of permeability of the second specimen is 5-times that of the first, the ratio of initial to final water heads in the test involving the second specimen is

Steady state seepage is taking place through a soil element at Q, 2 m below the ground surface immediately downstream of the toe of an earthen dam as shown in the sketch. The water level in a piezometer installed at P, 500 mm above Q, is at the ground surface. The water level in a piezometer installed at R, 500 mm below Q, is 100 mm above the ground surface. The bulk saturated unit weight of the soil is 18 kN/m3 and the unit weight of water is 9.81 kN/m3. The vertical effective stress (in kPa) at Q is

The flow net around a sheet pile wall is shown in the sketch. The properties of the soil are: permeability coefficient = 0.09 m/day (isotropic), specific gravity = 2.70 and void ratio = 0.85. The sheet pile wall and the bottom of the soil are impermeable.

The seepage loss (in m3 per day per unit length of the wall) of water is

The flow net around a sheet pile wall is shown in the sketch. The properties of the soil are: permeability coefficient = 0.09 m/day (isotropic), specific gravity = 2.70 and void ratio = 0.85. The sheet pile wall and the bottom of the soil are impermeable.

The factor of safety against the occurrence of piping failure is

For a saturated sand deposit, the void ratio and the specific gravity of solids are 0.70 and 2.67 respectively. The critical (upward) hydraulic gradient for the deposit would be

A sand layer found at sea floor under 20 m water depth is characterized with relative density=40%, maximum void ratio=1.0, minimum void ratio =0.5 and specific gravity of soil solids =2.67. Assume the specific gravity of sea water to be 1.03 and the unit weight of fresh water to be 9.81 kN/m3

what would be the effective stress(rounded off to the nearest integer value of kpa) at 30 m depth into the sand layer?

A sand layer found at sea floor under 20 m water depth is characterized with relative density=40%, maximum void ratio=1.0, minimum void ratio =0.5 and specific gravity of soil solids =2.67. Assume the specific gravity of sea water to be 1.03 and the unit weight of fresh water to be 9.81 kN/m3

what would be the change in the effective stress (rounded off to the nearest integer value of kpa) at 30 m depth into the sand layer if the sea water level permanently rises by 2 m?

Quick sand condition occurs when

A weir on a permeable foundation with downstream sheet pile is shown in the figure below. The exit gradient as per Khosla’s method is

Water emerges from an ogee spillway with velocity = 13.72 m/s and depth = 0.3 m at its toe. The tail water depth required to form a hydraulic jump at the toe is

The factor of safety of an infinite soil slope shown in the figure having the properties c = 0, $\mathrm\phi$ = 35°, ${\mathrm{\gamma }}_{\mathrm{dry}}$ = 16 kN/m3 and ${\mathrm{\gamma }}_{\mathrm{sat}}$ = 20 kN/m3 is approximately equal to

Match the following groups

 Group - I Group - II P Constant head permeability test 1 Pile foundations Q Consolidation test 2 Specific gravity R Pycnometer test 3 Clay soil S Negative skin friction 4 Sand

Water is flowing through the permeability apparatus as shown in the figure. The coefficient of permeability of the soil is k m/s and the porosity of the soil sample is 0.50.

The total head, elevation head and pressure head in metres of water at the point R shown in the figure are