Jannie Knudsen


Jannie Knudsen


Project title: Soil-pile interaction for bored cast-in-place piles in stiff clays and soft rocks

Project description:
According to the Danish National Annex to Eurocode 7, part I, the shaft resistance for a bored cast-in-place pile should not be assumed to be greater than 30 per cent of the shaft resistance of the corresponding driven pile, and the toe resistance is maximised to 1000 kPa. Since 1977 this principle has been enforced (code requirement) in Denmark, allegedly due to execution problems encountered in one or two un-documented case histories.

Hence, it is widely recognised that this reduction in bearing capacity is believed to be overly conservative. If the bored cast-in-place pile is established correct, the reduction of the shaft resistance is still applicable due to limited understanding of the governing mechanism and limited knowledge of the complex soil-pile interaction.

A consequence of this lack of understanding is that bored cast-in-place piles are often designed too conservative, and the bored cast-in-place piles are built more expensive than what is required.

This Industrial PhD project will investigate the shaft and toe resistance of bored cast-in-place piles based on full-scale field tests, model field tests, geotechnical and structural monitoring, and develop a first order analytical method for determination of the shaft (and toe) resistance for bored cast-in-place piles.

Supervisors: Professer (Docent) Kenny Kataoka Sørensen, Jørgen S. Steenfelt (COWI A/S) and Helle Trankjær (COWI A/S).

ID: 127113209