I have been interested for some time about what happens to the capacity of a steel pile when it has undergone some corrosion. I understand that in many circumstances, below groundwater table, steel piles driven into natural ground should suffer little if any corrosion.
However, in cases where corrosion does occur, one practice is to make an allowance for a layer of sacrificial steel, and structural design is based on the corroded section.
But what happens geotechnically to the shaft resistance? On the one hand, one might expect an increase in normal stress at the pile-soil interface because of the increased volume of the corrosion product relative to the parent steel. On the other hand, shear transfer is now through a steel- corrosion product-soil double interface, which could be expected to have a lower interface friction angle than the original steel-soil interface.
Does anyone have any information, research, experience or thoughts on this matter?