Franki pile is more useful where a bearing stratum of limited thickness can be reached at a reasonable depth, so y are best suited for granular type of soil.

The Raymond standard concrete pile consists of thin corrugated sheet steel closed at bottom that acts as a reinforcement.

Bored compaction piles are modification of under-reamed piles. These piles are also cast-in-situ piles, same as under-reamed piles.

The various stage involved in construction of under reamed pile foundation are i) boring by auger ii) under-reaming by under-reamer iii) placing reinforcement cage in position iv) concreting of pile caps, plinth beams and curtain walls.

In 1897, A.A. Raymond patented Raymond pile system and was first develop a practical, economical way of placing cast-in-situ concrete piles.

The maximum spacing of under-reamed pile should not normally exceed 2½ m as to avoid heavy capping beams.

Cast-in-situ piles can be classified in to two classes: driven piles(cased or uncased) and bored piles(pressure piles, pedestal piles and under reamed piles).

For clays, dynamic formulae are valueless because skin friction developed in clay during driving is very much less than which occurs after a period of time.

Generally diameter of under-reamed pile bulb is kept equal to 2.5 times diameter of pile steam. However, it may vary from 2 to 3 times stem diameter of pile steam.

Raymond standard pile and Raymond step-taper pile are common types of cast-in-situ piles.