GPSC Civil Engineering (Combine Exam) Paper Solution (03-05-26) – Page 14

131) Consider the following statements about Geosynthetics in foundation engineering:

1. Geogrids primarily provide reinforcement function due to their high tensile strength and interlocking with aggregate.
2. Geotextiles with woven structure have higher filtration efficiency than non-woven geotextiles.
3. The Apparent Opening Size (AOS) of a geotextile should be smaller than D85 of the base soil for effective filtration.
4. Geomembranes are primarily used as drainage layers in landfill liner systems.

Which of the statements given above are correct?

1. 1 and 3 only
2. 1, 2 and 3 only
3. 2 and 4 only
4. 1, 3 and 4 only

132) A fluid is flowing through a converging-diverging nozzle. Consider the following statements about flow behaviour:

1. In the converging section, velocity increases and pressure decreases for subsonic flow.
2. Separation of boundary layer is more likely in the converging section than in the diverging section.
3. Adverse pressure gradient in the diverging section promotes boundary layer separation.
4. Total pressure always remains constant throughout the nozzle in an ideal incompressible flow.

Which of the above statements are correct?

1. 1 and 3 only
2. 1 and 4 only
3. 1, 3 and 4 only
4. 1, 2 and 3 only

133) Consider the following statements about the Hydraulic Gradient Line (HGL) and Total Energy Line (TEL) in pipe flow:

1. HGL can rise above the pipe centre-line even if the pipe is flowing full.
2. TEL always slopes downward in the direction of flow due to head loss.
3. Difference between TEL and HGL equals the velocity head (V²/2g) at any section.
4. HGL coincides with TEL for a fluid at rest.

Which of the above statements are correct?

1. 2 and 3 only
2. 1 and 4 only
3. 1, 2, 3 and 4
4. 2, 3 and 4 only

134) In a Pelton wheel turbine, which combination of conditions gives the maximum hydraulic efficiency?

1. Bucket speed = jet speed; friction coefficient Cv = 1
2. Bucket speed = 0.5 × jet speed; no friction in bucket
3. Bucket speed = 0.5 x jet speed; deflection angle = 90°
4. Bucket speed = jet speed; deflection angle = 90°

135) Consider the following statements regarding dimensional analysis and model testing in hydraulic structures:

1. Froude number similarity is used for free-surface flows such as spillways and weirs.
2. Reynolds number similarity is used for pipe flow models where viscous forces dominate.
3. If both Froude and Reynolds similarities are simultaneously satisfied, the model fluid must be the same as the prototype fluid.
4. Weber number governs gravitational force effects.

Which of the above statements are correct?

1. 1 and 2 only
2. 1, 2, 3 and 4
3. 3 and 4 only
4. 1, 2 and 3 only

136) Consider the following statements regarding hydraulic jump in open channels:

1. A hydraulic jump mostly occurs when flow transitions from supercritical to subcritical.
2. The specific energy after a hydraulic jump is always greater than before the jump.
3. For a rectangular channel, the ratio of sequent depths y₂/y₁ depends only on the upstream Froude number Fr₁.
4. Energy loss in a hydraulic jump is always positive and equals the difference in specific energy across the jump.

Which of the above statements are correct?

1. 1 and 3 only
2. 1, 3 and 4 only
3. 2 and 4 only
4. 1, 2, 3 and 4

137) Which of the following statements about Francis turbine operation are correct?

1. Francis turbine is a mixed-flow reaction turbine where water enters radially and exits axially.
2. The degree of reaction of a Francis turbine is always 50%.
3. Draft tube in a Francis turbine helps recover kinetic energy at the runner exit.
4. Specific speed of Francis turbines is higher than that of Kaplan turbines.

1. 1 and 3 only
2. 2 and 4 only
3. 1, 3 and 4 only
4. 3 and 4 only

138) In pipe network analysis using the Hardy Cross method, consider the following statements:

1. The algebraic sum of head losses around any closed loop must be zero.
2. The continuity equation requires that inflow equals outflow at every junction node.
3. The correction factor ∆Q in each iteration uses the ratio of loop head loss to twice the absolute sum of resistance × flow.
4. Convergence is guaranteed in a single iteration for simple pipe networks.

Which of the above statements are correct?

1. 1, 2 and 3 only
2. 2 and 3 only
3. 1 and 2 only
4. 1, 2, 3 and 4

139) A rectangular channel of width 3 m carries a discharge of 12 m³/s. The depth of flow is 2 m. The channel is on a mild slope. Which of the following is correct?

1. Flow is supercritical
2. Flow is subcritical
3. Flow is critical
4. None of the above

140) Regarding the Buckingham Pi theorem, which of the following statements are correct?

1. If a physical phenomenon involves n variables and m fundamental dimensions, the number of dimensionless groups is (n – m).
2. The selection of repeating variables must span all fundamental dimensions present.
3. Repeating variables must themselves be dimensionally independent of each other.
4. The choice of repeating variables affects the form but not the number of Pi terms.

1. 1 and 2 only
2. 2 and 3 only
3. 1, 2 and 3 only
4. 1, 2, 3 and 4