What is the ultimate capacity in kN of the pile group shown in the figure assuming the group to fail as a single block?
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Solution
Ultimate capacity of pile group
Qb = AB.C.NC+As.C
= (1.2 +0.4)2× 45 × 9 + 4 × (1.2 + 0.4) × 12 × 45
= 4492.8 kN
Assuming that a river bed bend does not change and the depth of water in river was 10m,15m and 8 m during months of February, July and December respectively of a particular year. The average bulk density of soil is 20 kN/m3. The density of water is 10 kN/m3. The effective stress at depth of 10 m below the river bed during these months would be
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Solution
Effective stress, σ' = γz
Cut does not depend on depth of water above bed level.
γ' = γsal + γw
= 20 – 10
= 10 kN/m3
= 100 kPa
For all 3 months, σv' is same.
If porosity of soil sample is 18%, the void ratio is_______.
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Solution
To have zero active pressure intensity at the tip of a wall in cohesive soil, one should apply a uniform surcharge intensity of
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Solution
Basic runway length should be increased by ________ %for every 300m rise in elevation from MSC.
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Solution
7
Flownet drawn for a weir, total head loss is 6m, number of potential drops in 10 and length of the flow path for the last square is 1m. The exit gradient is ________ .
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Solution
A 25 kN point load acts on the surface of an infinite elastic medium. The vertical pressure intensity in kN/m2 at a point 6.0 m below and 4.0 m away from the load will be ________ .
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Solution
A retaining wall of height 8 m retain dry sand. In the initial state, soil is loose and has a void ratio of 0.5, γd= 17.8kN/m3 and φ= 30. Subsequently, the back fill is compacted to a state where void ratio is 0.4, γd= 18.8 kN/m3 and φ= 35. The ratio of initial passive thrust to the final passive, according to Rankine’s earth pressure theory,is________ .
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Solution
The MLSS concentration in the aeration tank of extended aeration activated sludge process is 4000 mg/I. If one litre of sample settled in 30 minutes and the measuring cylinder showed a sludge volume of 200 ml, then the sludge volume index would be nearly ________ .
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Solution
In a triaxial test carried out on a cohesionless soil sample with a cell pressure of 20 kPa, the observed value of applied stress at the point of failure was 4 kPa. The angle of internal friction on the soil is
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Solution