In order to reduce uplift on a gravity dam, the type of grouting done is ____________________

Consider the following statements in respect of dams: 1. In a gravity dam, a grout curtain is provided near the toe to reduce the exit gradient. 2. A drainage gallery with its drainage pipe system provided in a gravity dam reduces the uplift pressure at all levels below the upstream water level. 3. An earthquake acceleration of 0.1 g acting vertically downward causes a decrease of 10% in the limit weight of concrete and of water in a gravity dam. 4. The Tehri dam is a gravity dam. Which of the above statements are correct?

A

1 and 3 only

B

1 and 4 only

C

2 and 3 only

D

2 and 4 only

Consider the following statements related to uplift pressure in gravity dams: 1. A drainage gallery reduces the uplift pressure at all levels below the gallery. 2. A drainage gallery below upstream water level reduces the uplift pressure at all levels below the upstream water level. 3. A grout curtain near the heel reduces seepage and uplift pressure everywhere on the gravity dam whatever the upstream water level. Which of the above statements are correct?

A

2 and 3 only

B

1 and 2 only

C

1 and 3 only

D

1, 2 and 3

Which of the following attempts are made to reduce the uplift in order to economize on the provided section of a concrete gravity dam? i. Providing drainage gallery to collect seepage water ii. Constructing cut-off under upstream face iii. Pressure grouting in dam foundation iv. Provision of shear keys or keyways

A

i and ii

B

i, ii and iii

C

i, ii and iv

D

i, ii, iii and iv

The base width of a solid gravity dam is 35 m and the specific gravity of dam material is 2.45. What is the approximate allowable height of the dam having an elementary profile without considering the uplift?

A

64.68 m

B

54.80 m

C

164 m

D

80 m

A concrete gravity dam having a maximum reservoir level at 200 m and the RL of the bottom of the dam 100 m. The maximum allowable compressive stress in concrete is 3000 KN/m2 and the specific gravity of concrete is 2.4. Calculate the height of the dam and check whether it is a high dam or low dam.

A

H = 90 m High gravity dam

B

H = 90 m Low gravity dam

C

H = 214.2 m High gravity dam

D

H = 214.2 m Low gravity dam

The uplift pressure on a dam can be controlled byi) constructing cutoff under upstream faceii) constructing drainage channels bet-ween the dam and its foundationiii) by pressure grouting in foundationThe corret answer is

A

only (i)

B

both (i) and (ii)

C

both (i) and (iii)

D

(i), (ii) and (iii)

The ratio of base width 'b' to height 'h' of an elementary profile of a gravity dam, from 'no tension' consideration, is given by Where G = specific gravity of dam material K = uplift pressure intensity and μ = coefficient of friction

A

\(\frac{1}{{\sqrt {G - K} }}\)

B

\(\frac{1}{{(G - K)\mu }}\)

C

\(\frac{1}{{\sqrt {G - K} \mu }}\)

D

\(\frac{1}{{\sqrt {({G^2} - {K^2})} }}\)

The ratio of base width ‘b’ to height ‘h’ of an elementary profile of a gravity dam from ‘no tension’ consideration is given by Where G = specific gravity of dam material K = uplift pressure intensity μ = coefficient of friction

A

\(1/\sqrt{(G - K)}\)

B

1/(G - K)μ

C

1

D

\(1/\sqrt{(G^2 - K^2)}\)

A low gravity dam of elementary profile made up of concrete of relative density 2.57 and safe allowable stress of foundation material 4.2 MPa. What is the maximum height of the dam without considering the uplift force?

A

120 m

B

217 m

C

279 m

D

325 m

Availability of drinking water is continuously decreasing. The government decided to identify those sources of drinking water which getting polluted. The following table depicts the number of polluted sources in a district. Source of drinking water getting polluted Number Wells 24 Handpump 12 Dam 12 Borewell 6 Ponds 18 The pictograph table for the above table will be (A) Source of drinking water getting polluted Number symbol = 6 source Wells Handpump Dam Borewell Ponds (B) Source of drinking water getting polluted Number symbol = 6 source Wells Handpump Dam Borewell Ponds (C) Source of drinking water getting polluted Number symbol = 6 source Wells Handpump Dam Borewell Ponds (D) Source of drinking water getting polluted Number symbol = 6 source Wells Handpump Dam Borewell Ponds

A

B

C

D

C

In order to reduce uplift on a gravity dam, the type of grouting done is ____________________

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