Module 5 : Design of Deep Foundations
Lecture 20 : Introduction [ Section 20.2 : Design Methodology For Piles ]
   
Raymond piles. (Driven cast-in-situ piles, first tapered shell is driven and then cast)
Franki Piles (Driven cast-in-situ piles, first casing is driven upto 2m depth, then cast a block within that casing and then drive the block. When it reaches the particular depth, take out the casing and cast the piles.)
 
Underreamed piles (bored cast-in-situ piles, bulbs used, hence not possible to install in loose sand and very soft clays.)
  PILES IN CLAY
  Zone of influence
 
 
Fig.5.2 Driven piles in clay
 

The heaving effect can be felt upto (10 –15) D from the centerline of the pile. Due to driving load, pressure is generated and as a result heaving occurs. Afterwards with time, the heaved part gets consolidated and strength gradually increases as the material regains shear strength within 3 – 6 months time after the installation of the pile. This regain of strength is called thixotrophy.

   
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