We are construction foundations consisting of 2,400mm diameter bored piles, 14,000mm deep. Bored pile terminates at ground surface. Subsurface materials are a thin layer of silty sand followed by mostly weathered tuff for the length of the pile so will use bentonite or Supermud for drilling...
This is about a problem we are having for a 1.5m bored pile construction The following is the situation:
1. Boring data shows loose silty fine sand from surface to depth -5m, underlain by soft to medium stiff silty clay (N value=2 to 6) to -25m depth after which depth the clay becomes stiffer...
