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Question 1
ప్రశ్న 1
Which set correctly identifies the principal components of a conventional RCC cantilever retaining wall?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
A cantilever retaining wall normally consists of a vertical or nearly vertical stem connected monolithically to a base slab. The part of the base extending beneath the retained backfill is called the heel. The portion projecting in front of the stem is called the toe. These components act together structurally and also provide the weight and base width required for external stability. Therefore Option A is correct.
వివరణ:
Question 2
ప్రశ్న 2
Which statement correctly distinguishes the geotechnical and structural parts of retaining-wall design?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Earth pressure is obtained from geotechnical principles using the relevant soil, groundwater, surcharge and wall-movement conditions. External stability then considers sliding, overturning and the distribution of bearing pressure beneath the base. These calculations provide the actions that the reinforced concrete wall must safely transmit. The stem, heel and toe are subsequently checked structurally for bending, shear, reinforcement and detailing under the appropriate design actions. Therefore Option A is correct.
వివరణ:
Question 3
ప్రశ్న 3
For a retaining wall supporting dry cohesionless backfill, when is the active earth-pressure condition mobilized?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Active earth pressure is associated with a wall that yields away from the retained soil sufficiently to mobilize the active state. The lateral pressure decreases from the at-rest condition as the wall moves outward. A wall moving toward the backfill tends instead toward the passive state. A wall that is effectively restrained from moving may need an at-rest pressure rather than an active-pressure assumption. Therefore Option A is correct.
వివరణ:
Question 4
ప్రశ్న 4
For a smooth vertical retaining wall with horizontal cohesionless backfill under Rankine conditions, what is the active earth-pressure coefficient Ka when the soil friction angle is 30 degrees?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For the stated Rankine conditions, Ka = (1 - sinφ)/(1 + sinφ). With φ = 30 degrees, sinφ = 0.5. Thus Ka = (1 - 0.5)/(1 + 0.5) = 0.5/1.5 = 1/3. Numerically this is approximately 0.333. Therefore Option B is correct.
వివరణ:
Question 5
ప్రశ్న 5
A retaining wall supports 5.0 m of dry horizontal cohesionless backfill with unit weight 18 kN/m³. Take Ka = 1/3 and neglect surcharge and water pressure. What total active earth thrust acts per metre length of wall?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For dry cohesionless backfill without surcharge, the lateral active pressure increases linearly from zero at the surface to KaγH at the base. The resultant thrust is therefore Pa = 0.5KaγH². Substitution gives 0.5 × (1/3) × 18 × 5². This evaluates to 75 kN per metre length of wall. Therefore Option C is correct.
వివరణ:
Question 6
ప్రశ్న 6
At what height above the base does the resultant of the triangular active earth pressure caused solely by the self-weight of a uniform dry backfill act?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The lateral pressure caused by the self-weight of uniform cohesionless backfill has a triangular distribution with depth. The resultant of a triangular load acts at one-third of its height measured from the larger-intensity end. The maximum earth pressure occurs at the bottom of the wall. Hence the resultant acts at H/3 above the base. Therefore Option B is correct.
వివరణ:
Question 7
ప్రశ్న 7
The same 5.0 m high wall is also subjected to a uniform surcharge q = 15 kN/m² on the horizontal backfill. With Ka = 1/3, what additional lateral thrust is produced by the surcharge?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
A uniform surcharge produces a uniform additional vertical stress q throughout the backfill depth. Under the stated active-pressure model, the corresponding uniform lateral pressure is Kaq. Its resultant over height H is therefore Paq = KaqH. Substituting gives (1/3) × 15 × 5 = 25 kN/m. Therefore Option C is correct.
వివరణ:
Question 8
ప్రశ్న 8
For the 5.0 m wall with soil thrust 75 kN/m acting at H/3 and surcharge thrust 25 kN/m acting at H/2, what total overturning moment about the base of the stem is produced by these lateral actions?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The soil-weight component produces a moment of 75 × (5/3) = 125 kN·m/m. The uniform surcharge component acts at mid-height and produces 25 × 2.5 = 62.5 kN·m/m. The two moments act in the same overturning direction. Their total is 125 + 62.5 = 187.5 kN·m per metre length. Therefore Option C is correct.
వివరణ:
Question 9
ప్రశ్న 9
If water is allowed to build up to a depth of 4.0 m behind a wall, what hydrostatic thrust acts per metre length due solely to the water when γw = 10 kN/m³?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Hydrostatic pressure increases linearly with depth according to γwz. The resultant pressure over height H is therefore 0.5γwH². With H = 4.0 m and γw = 10 kN/m³, the force is 0.5 × 10 × 4². This gives 80 kN per metre length, acting at H/3 above the base. Therefore Option C is correct.
వివరణ:
Question 10
ప్రశ్న 10
A retaining wall has total vertical stabilizing force V = 500 kN/m and a base-interface friction coefficient μ = 0.40. If the total driving horizontal force is 100 kN/m and passive resistance is neglected, what is the factor of safety against sliding based only on base friction?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The available frictional resistance is μV when only base friction is included. Here the resistance is 0.40 × 500 = 200 kN/m. The factor of safety against sliding is the resisting horizontal force divided by the driving horizontal force. Thus FS = 200/100 = 2.00. Therefore Option C is correct.
వివరణ:
Question 11
ప్రశ్న 11
Why is passive earth resistance in front of a retaining-wall toe sometimes neglected or used cautiously in a sliding-stability calculation?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Passive resistance can contribute to resistance against sliding when soil remains reliably in front of the footing. However, comparatively large movement may be required before full passive resistance is mobilized. The soil in front of the wall may also be excavated, eroded or otherwise disturbed during the service life. Neglecting uncertain passive resistance can therefore provide a conservative stability assessment. Therefore Option A is correct.
వివరణ:
Question 12
ప్రశ్న 12
A retaining wall has stabilizing moments of 450 kN·m/m and overturning moments of 187.5 kN·m/m about its toe. What is the factor of safety against overturning?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The factor of safety against overturning is the ratio of stabilizing moments to overturning moments about the selected reference point, commonly the toe. Here the ratio is 450/187.5. This equals 2.40. The adequacy of that value must then be judged against the criterion applicable to the particular standard and loading condition. Therefore Option C is correct.
వివరణ:
Question 13
ప్రశ్న 13
Under the static-load stability criteria specifically stated in IS 14458 (Part 2) for retaining and breast walls in hill areas, which pair of factors of safety is specified?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
IS 14458 Part 2 provides stability criteria for retaining and breast walls within its hill-area scope. For static loading, it states a factor of safety greater than 2.0 against overturning. It also states a factor of safety greater than 1.5 against sliding. These values should not be presented as universal factors for every retaining structure under every loading code or seismic condition. Therefore Option C is correct.
వివరణ:
Question 14
ప్రశ్న 14
For a retaining wall base of width B, what eccentricity condition keeps the resultant within the middle third and prevents tensile base pressure under a linear full-contact pressure assumption?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The base-pressure distribution is commonly treated as linear when the base remains in full contact with the supporting soil. At an eccentricity equal to B/6, the pressure at one edge just becomes zero. If the eccentricity is smaller, both edge pressures remain compressive. An eccentricity larger than B/6 would cause the full-contact linear calculation to predict tension at one edge. Therefore Option C is correct.
వివరణ:
Question 15
ప్రశ్న 15
For a retaining-wall base carrying a vertical resultant V per metre length with eccentricity e from the centre of a base of width B, which expression gives the extreme pressures when full contact is maintained?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The average pressure under a base of unit length is V/B. Eccentricity adds a linearly varying pressure component arising from the moment Ve. For a rectangular base, combining direct and bending stress gives qmax,min = (V/B)(1 ± 6e/B). The expression assumes full contact and a linear elastic-type distribution of soil reaction. Therefore Option A is correct.
వివరణ:
Question 16
ప్రశ్న 16
A retaining-wall base is 4.0 m wide and carries a vertical resultant of 600 kN/m acting 0.30 m from the centre toward the toe. What are the toe and heel pressures respectively?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The average base pressure is V/B = 600/4 = 150 kN/m². The eccentricity factor is 6e/B = 6 × 0.30/4 = 0.45. Because the resultant is shifted toward the toe, the toe pressure is the larger value, 150(1 + 0.45) = 217.5 kN/m². The heel pressure is 150(1 - 0.45) = 82.5 kN/m². Therefore Option A is correct.
వివరణ:
Question 17
ప్రశ్న 17
Which condition is required in an ordinary retaining-wall bearing-pressure stability check when full soil contact is intended?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The foundation soil must safely support the maximum compressive reaction developed beneath the base. Thus the maximum calculated contact pressure should not exceed the applicable allowable bearing pressure for the design condition. Soil tension is ordinarily not relied upon in a conventional shallow retaining-wall foundation. The minimum pressure should consequently remain non-negative when full base contact is assumed. Therefore Option A is correct.
వివరణ:
Question 18
ప్రశ్న 18
How does the stem of a conventional RCC cantilever retaining wall primarily behave structurally under lateral earth pressure?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The stem projects upward from the base slab and is subjected to lateral pressure from the retained soil. It therefore behaves primarily as a vertical cantilever fixed at its junction with the base. For the usual direction of retained-earth loading, the backfill face is the principal tension face near the base of the stem. The main vertical reinforcement is consequently concentrated toward that face while appropriate secondary reinforcement is also provided. Therefore Option A is correct.
వివరణ:
Question 19
ప్రశ్న 19
A 5.0 m retaining-wall stem is subjected to a triangular soil thrust of 75 kN/m and a uniform-surcharge thrust of 25 kN/m. What are the base shear and base bending moment in the stem due to these lateral actions?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The base shear equals the sum of the horizontal force resultants acting on the stem. Hence the shear is 75 + 25 = 100 kN/m. The triangular component contributes 75 × 5/3 = 125 kN·m/m. The surcharge component contributes 25 × 2.5 = 62.5 kN·m/m, giving a total moment of 187.5 kN·m/m. Therefore Option B is correct.
వివరణ:
Question 20
ప్రశ్న 20
For the usual loading condition in which the weight of soil over the heel exceeds the upward soil reaction sufficiently to produce net downward loading on the heel projection, where is the principal flexural tension reinforcement generally required near the stem?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The heel projects beneath the retained backfill and behaves as a cantilever from the stem. It carries upward foundation reaction but also downward loads from the retained soil, surcharge where applicable, and its own weight. Under the usual case specified in the question, the net loading produces negative cantilever bending near the stem. The top face is then the principal tension face and requires the main heel reinforcement. Therefore Option A is correct.
వివరణ:
Question 21
ప్రశ్న 21
For the usual condition in which upward soil reaction governs the net loading on the toe slab, where is its principal flexural tension reinforcement generally placed near the stem?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
The toe slab projects forward from the stem and behaves structurally as a cantilever. The supporting soil reaction acts upward over the toe area, while self-weight acts downward. When the net action is upward as stated, the cantilever bends in the opposite sense to a normally downward-loaded cantilever. This produces principal flexural tension near the bottom face close to the stem, so main toe reinforcement is generally placed there. Therefore Option A is correct.
వివరణ:
Question 22
ప్రశ్న 22
A 1.0 m long toe projection is subjected to a net uniform upward design pressure of 120 kN/m². Treating a one-metre strip as a cantilever fixed at the stem face, what is the design bending moment at the stem face?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For a one-metre strip, a pressure of 120 kN/m² gives a line load of 120 kN/m. The toe is idealized as a cantilever of length 1.0 m fixed at the stem face. Its fixed-end moment under a uniform load is wL²/2. Thus the moment is 120 × 1²/2 = 60 kN·m per metre width. Therefore Option B is correct.
వివరణ:
Question 23
ప్రశ్న 23
A heel projection extends 1.5 m behind the stem and is subjected to a net uniform downward design load of 80 kN/m². For a one-metre strip acting as a cantilever, what is the bending-moment magnitude at the stem face?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
For a one-metre strip, the net line load is 80 kN/m. The cantilever length of the heel is 1.5 m. The fixed-end moment magnitude is wL²/2 = 80 × 1.5²/2. This evaluates to 90 kN·m per metre width, with the corresponding tension face determined by the downward loading direction. Therefore Option C is correct.
వివరణ:
Question 24
ప్రశ్న 24
What is the effect of adding a uniform surcharge to otherwise unchanged horizontal cohesionless backfill behind a cantilever retaining wall?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
A uniform surface surcharge increases the vertical stress in the retained soil by q. Under the stated active-pressure model, this produces an additional lateral pressure equal to Kaq. Because the added pressure is uniform with depth, its resultant acts at mid-height of the retained soil. It consequently increases the lateral force on the stem and also adds an overturning moment about the base. Therefore Option A is correct.
వివరణ:
Question 25
ప్రశ్న 25
Which sequence best represents a sound design approach for a conventional RCC cantilever retaining wall?
Select an option first. || ముందుగా ఒక సమాధానాన్ని ఎంచుకోండి.
Explanation:
Retaining-wall design begins with a realistic assessment of the retained material, groundwater, surcharge and applicable earth-pressure state. These actions are combined with wall and soil weights to assess sliding, overturning, resultant location and foundation bearing pressure. Once a stable preliminary geometry is established, the resulting pressures and forces are used to determine structural actions in the stem and base projections. The reinforced concrete members are then designed and detailed for strength, serviceability, anchorage and durability as applicable. Therefore Option A is correct.
వివరణ:
Answer Key సమాధానాల పట్టిక
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Question 1 ప్రశ్న 1Answer: A. Stem, heel slab and toe slab సమాధానం: A.
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Question 2 ప్రశ్న 2Answer: A. Earth pressure, sliding, overturning and bearing are external-stability issues, while the stem and base slabs are structurally designed for the resulting forces and moments సమాధానం: A.
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Question 3 ప్రశ్న 3Answer: A. When the wall moves sufficiently away from the retained soil సమాధానం: A.
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Question 4 ప్రశ్న 4Answer: B. 0.333 సమాధానం: B.
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Question 5 ప్రశ్న 5Answer: C. 75 kN/m సమాధానం: C.
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Question 6 ప్రశ్న 6Answer: B. H/3 సమాధానం: B.
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Question 7 ప్రశ్న 7Answer: C. 25 kN/m సమాధానం: C.
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Question 8 ప్రశ్న 8Answer: C. 187.5 kN·m/m సమాధానం: C.
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Question 9 ప్రశ్న 9Answer: C. 80 kN/m సమాధానం: C.
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Question 10 ప్రశ్న 10Answer: C. 2.00 సమాధానం: C.
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Question 11 ప్రశ్న 11Answer: A. Because full passive resistance may require substantial movement and the soil in front of the wall may later be disturbed or removed సమాధానం: A.
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Question 12 ప్రశ్న 12Answer: C. 2.40 సమాధానం: C.
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Question 13 ప్రశ్న 13Answer: C. Overturning greater than 2.0 and sliding greater than 1.5 సమాధానం: C.
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Question 14 ప్రశ్న 14Answer: C. |e| ≤ B/6 సమాధానం: C.
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Question 15 ప్రశ్న 15Answer: A. qmax,min = (V/B)(1 ± 6e/B) సమాధానం: A.
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Question 16 ప్రశ్న 16Answer: A. 217.5 kN/m² and 82.5 kN/m² సమాధానం: A.
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Question 17 ప్రశ్న 17Answer: A. Maximum pressure should not exceed the allowable bearing pressure and minimum pressure should remain non-negative సమాధానం: A.
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Question 18 ప్రశ్న 18Answer: A. As a vertical cantilever fixed at the base slab, with principal vertical tension reinforcement generally near the backfill face సమాధానం: A.
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Question 19 ప్రశ్న 19Answer: B. 100 kN/m and 187.5 kN·m/m సమాధానం: B.
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Question 20 ప్రశ్న 20Answer: A. Near the top face of the heel slab సమాధానం: A.
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Question 21 ప్రశ్న 21Answer: A. Near the bottom face సమాధానం: A.
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Question 22 ప్రశ్న 22Answer: B. 60 kN·m/m సమాధానం: B.
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Question 23 ప్రశ్న 23Answer: C. 90 kN·m/m సమాధానం: C.
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Question 24 ప్రశ్న 24Answer: A. It adds an approximately uniform lateral pressure Kaq over the wall height and increases both lateral thrust and overturning moment సమాధానం: A.
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Question 25 ప్రశ్న 25Answer: A. Establish soil, water and surcharge actions; check external stability and bearing; then structurally design the stem, heel and toe for the resulting actions సమాధానం: A.