# GATE Questions & Answers of Deep foundations - Types of piles

## What is the Weightage of Deep foundations - Types of piles in GATE Exam?

Total 8 Questions have been asked from Deep foundations - Types of piles topic of Foundation Engineering subject in previous GATE papers. Average marks 1.75.

It is proposed to drive H-piles up to a depth of 7 m at a construction site. The average surface area of the H-pile is 3m2 per meter length. The soil at the site is homogeneous sand, having an effective friction angle of $\style{font-family:'Times New Roman'}{32^\circ}$. The ground water table (GWT) is at a depth of 2 m below the ground surface. The unit weights of the soil above and below the GWT are 16kN/m3 and 19kN/m3, respectively. Assume the earth pressur coefficent, = 1.0, and the angle of wall friction, $\style{font-family:'Times New Roman'}{\delta=23^\circ}$. The total axial frictional resistance (in kN, up to one decimal place) mobilized on the pile against the driving is _______________

The action of negative skin friction on the pile is to

A single vertical friction pile of diameter 500 mm and length 20 m is subjected to a vertical compressive load. The pile is embedded in a homogeneous sandy stratum where: angle of internal friction (φ) = 30°, dry unit weight (γd) = 20 kN/m3 and angle of wall friction (δ) = 2φ/3. Considering the coefficient of lateral earth pressure (K) = 2.7 and the bearing capacity factor (Nq) = 25, the ultimate bearing capacity of the pile (in kN) is _______________

A singly under-reamed, 8-m long ,RCC pile(shown in the adjoining figure) weighing 20 kN with 350 mm shaft diameter and 750 mm under-ream diameter is installed within stiff, saturated silty clay(undrained shear strength is 50 kpa, adhesion factor is 0.3, and the applicable bearing capacity factor is 9) to counteract the impact of soil swelling on a structure constructed above. Neglecting suction and the contribution of the under-ream to the adhesive shaft capacity, what would be the estimated ultimate tensile capacity(rounded off to the nearest interger value of kN) of the pile?

The ultimate load capacity of a 10 m long concrete pile of square cross section 500 mm x 500 mm driven into a homogeneous clay layer having undrained cohesion value of 40 kPa is 700 kN. If the cross section of the pile is reduced to 250 mm x 250 mm and the length of the pile is increased to 20m, the ultimate load capacity will be

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