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Consider the following statements about the under-reamed pile in swelling soils:
1. Its bulb provides anchor against movement due to volume changes of soil.
2. It is a driven pile.
3. Its bulb diameter is 2.5 times its shaft diameter.
Which of these statements are correct?
Under-reamed pile is a special type of bored pile which is provided with a bulb/pedestal at the end. The usual size of such piles are 150 to 200 mm shaft diameter, 3 to 4 m long. The diameter of under-reamed portion is usually 2 to 3 times the shaft diameter.
Consider the following statements:
1. Piles are provided in groups, which are connected together by a pile cap. The structure rests on top of the pile cap. The pile cap is situated below the ground level.
2. For situations where pile is subjected to upward pull, pedestal piles or under reamed piles are more suitable type of foundations.
Which of these statements is/are correct?
A square pile of section 30 cm x 30 cm and length 10 m penetrates a deposit of clay having c = 5 kN/m2 and the mobilizing factor α = 0.8. What is the load carried by the pile by skin friction only?
The load carried by skin-friction only
In the Engineering News Record formula for determining the safe load, carrying capacity of a pile, the factor of safety used is
Pile driven in deep clay deposits transfers its loads by
For clay deposits ultimate load of pile is given by,
cNcAp accounts for end bearing while accounts for frictional resistance.
Resistance load due to skin friction for a pile varies with
Resistance load due to skin friction As is surface area of pile over which skin friction acts = π D x L = πLD
In pile foundation, the skin friction and end bearing are separated by
Static formula gives the ultimate capacity of an individual pile
Hileys formula and Engineering news formula are dynamic formula to calculate the load-carrying capacity of a driven pile
In Cyclic loading test an incremental load is repeatedly applied and removed to separate skin friction and end bearing of a pile.
The settlement ratio of pile group is generally
The settlement of a group of piles in more than the settlement of a single pile even when the load on the single pile and the load on each pile of the pile group are same. This is because of the fact that the zone of influence of a pile group is much deeper than that of a single pile.