I would like to design bored cast-in-situ piles in weathered rock in South Africa. Has somebody information on the practice of designing piles as friction piles with no end bearing for diameter < 750 mm (where no manual bottom cleaning is possible!)? Is it a South African Standard requirement? I have never heard of a so restrictive practice in Europe. Thank you
I suppose when you want a safer (or is data is uncertain) practice, then you do not include the end-bearing component of the total capacity. The end bearing will serve to be a bonus. However since no cleaning, the end bearing will expectedly be low due to debris collection.
In practice when i'm not certain, I don't only disregard the end-bearing component, I also consider a smaller perimeter as my effective perimeter for additional safety against installation errors or unexpectant occurances.