Dynamic Method

Q. A precast concrete pile is driven with a $50\text{kN}$ hammer falling through a height of $1.0\text{m}$ with an efficiency of 0.6. The set value observed is $4\text{mm}$ per blow and the combined temporary compression of the pile, cushion and the ground is $6\text{mm}$. As per Modified Hiley Formula, the ultimate resistance of the pile is

1. $3000\text{kN}$
2. $4285.7\text{kN}$
3. $8333\text{kN}$
4. $11905\text{kN}$

Q. A drop hammer is used to drive a wooden pile. The hammer weight is 25 kN and its free falling height is 0.8 m. The penetration in the last blow is 12 mm. What is the nearest approximation to the load carrying capacity of the pile according to the Engineering News Formula?

1. 125 kN
2. 110 kN
3. 3000 kN
4. 90 kN

Q. In the Engineering News Recorded formula for determining the safe load carrying capacity of a pile, the factor of safety used is

1. 2.5
2. 3
3. 4
4. 6

Q. A timber pile is being driven with a drop hammer weighing 25 kN and having a free fall of 1.2 m. The average penetration of the pile is 6 mm. What will be the load carrying capacity of pile using the Engineering News Formula ?

1. 140 kN
2. 160 kN
3. 180 kN
4. 200 kN

Q. In which one of the following conditions, is the pile system as shown in figure highly inappropriate ?

1. 
2. 
3. 
4. 

Q. A timber pile of length 8m and diameter of 0.2m is driven with a 20 kN drop hammer, falling freely from a height of 1.5m. The total penetration of the Pile in the last 5 blows is 40mm. Use the engineering news record expression. Assume a factor of safety of 6 and empirical factor (allowing reducing in the theoretical set, due to energy losses) of 2.5 cm. The safe load carrying capacity Of the pile (in kN, round off to 2 decimal places) is

1. 151.515

Q. The Engineering News Record Formula, $Q_a=\frac{Wh}{6(s+0.25)},isusedforthecaseof$

1. Drop hammer
2. Single-acting hammer
3. Doubl-acting hammer

Which of the above is/are correct?

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

Q. Direction : The following items consists of two statements; one labelled as 'Assertion (A)' and the other as 'Reason (R)'. You are to examine these two statements carefully and select the answers to these items using the codes given below:

Codes :

Assertion (A) : Pile driving formulae have very limited use in the case of cohesive soils.

Reason (R) : Pile driving in cohesive soils results in liquefaction of clays.

1. both A and R are true and R is the correct explanation of A
2. both A and R are true but R is not a correct explanation of A
3. A is true but R is false
4. A is false but R is true

Q. Consider the following statements:

1. Dynamic resistance of a soil is not much different from its static resistance.
2. The most comprehensive pile driving formula is Hiley's formula.
3. Pile driving formulae are more useful if the subsoil consists of coarse grained soil.

Which of the above statements are correct?

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