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GATE CE 2020 Geotech. Engg. Quiz 12 (App update required to attempt this test)
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Question 1
The interstices in a clay are of size equal to one tenth of the mean diameter of the grain. The height to which water will rise in the clay soil of average grain diameter 0.10 mm is _______ m.
[Assume surface tension at air-water interface as 0.073 N/m]
[Assume surface tension at air-water interface as 0.073 N/m]
Question 2
Water table of an aquifer drops by 100 cm over an area of 1000 km2. The porosity and specific retention of the aquifer material are 25% and 5%, respectively. The amount of water (expressed in km3) drained out from the area is ______ .
Question 3
A gravity well has a diameter of 60 cm. The depth of water in the well is 40 m before pumping is started. When pumping is being done at the rate of 2000 litres per minute, the drawdown in a well 10 m away is 4 m and in another well 20 m away is 2 m. What will be the radius (in m) of zero drawdown?
Question 4
An aquifer of 25 m average thickness is overlain by an impermeable layer of 30 m thickness. A test well of 0.5 m diameter and two observation wells at a distance of 18 m and 65 m from the test well were drilled through the aquifer. After pumping at a rate of 0.2 m3/s for a long time, the following drawdown were stabilized in these wells
(i) First observation well = 4 m
(ii) Second observation well = 3 m
The drawdown (in m) in the test well is
(i) First observation well = 4 m
(ii) Second observation well = 3 m
The drawdown (in m) in the test well is
Question 5
A concrete gravity dam section is shown in the figure. Assuming unit weight of water as 10kN/m3 and unit weight of concrete as 24kN/m3, the uplift force per unit length of the dam (expressed in kN/m) at PQ is ____________.
Question 6
A confined aquifer of 15 m constant thickness is sandwiched between two aquicludes as shown in the figure (not drawn to scale)
The heads indicated by two piezometers P and Q are 55.2 m and 34.1 m, respectively. The aquifer has a hydraulic conductivity of 80 m/ day and its effective porosity is 0.25. If the distance between the piezometers is 2500 m, the time taken by the water to travel through the aquifer from piezometer location P to Q (in days, round off to 1 decimal place) is ______.
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