The Engineers News formula as proposed by Wellington and Hiley?s formula given by original expression of Hiley are commonly used dynamic formula.

Single acting hammers are advantageous when driving heavy piles in compact or hard piles.

The result of Dutch cone penetration test can be applied with sufficient accuracy to determine ultimate bearing capacity of piles in cohesion soils.

The static formulae are based on assumption that ultimate bearing capacity Qup of a pile is sum of total ultimate skin friction Rf and total ultimate point or end bearing resistance Rp:
Qup = Rf + Rp.

The area of pile group, along failure surface is approximately equal to perimeter P of pile group multiplied by length L of pile.

The following are common types of uncased cast-in-situ concrete piles:
i) Simplex pile
ii) Vibro pile
iii) Franki pile
iv) Padestal pile.

The procedure of construction in bored piles is different than cast-in-situ driven pile where heavy pile driving equipment is required.

Design of grade beam, depth of beam and reinforcement required for various loading is provided by Central Building Research Institute, Roorkee.

Under-reaming or enlarging stem of bore hole at required depths is achieved by means of under-reamer consisting of a set of two collapsible blade assembly.

The bearing capacity of vibro-expanded piles is increased by enlarging its diameter at bottom.