End bearing piles 1

[downunder73]

A two-storey building on a highly reactive site is founded on a grid of piles. The soil profile shows a 4m deep reactive clay horizon overlying a deep profile of dense sands. Could there be a problem with founding the piles at the top of the dense sand?

 

[hokie66]

Yes, the clay in changing volume could move the piles up and down if the supported loads are light. The piles should be founded deep enough in the sand to resist any uplift, and the piles designed for the resulting tension. As well, the structure supported on the piles should be isolated from the swelling material with a void former. Your geotech should be able to give you the design parameters for the uplift.