Dynamic response of driven end-bearing piles and a pile group in soft clay: an experimental validation study

This paper presents novel measurement data on the dynamic soil-structure interaction of an end-bearing pile foundation. The purpose is to assess the ability to predict the foundation impedances based on the small-strain properties of the soil obtained from site investigations. Measurements were performed in two stages of construction, allowing to assess interaction between the piles through the soil. First, single pile impedances and interaction factors between the piles were experimentally obtained for the four piles when they were free to move at the surface. Second, the impedances of the square pile group were measured after casting a concrete pile cap. The piles were additionally instrumented with accelerometers at depth along the centerline of each pile, allowing to illustrate the global behaviour of the piles within the soil. Numerical predictions based solely on information of the small-strain soil properties obtained from extensive site investigations are compared to the experimental results. The impedances of the individual piles are overestimated compared to the measurements, while the interaction factors show a better agreement. The pile group impedances are better captured than the individual ones, using the same soil model. The pile-soil-pile interaction is clearly manifested in the experimental results by pronounced peaks in the pile group vertical impedance, validating results from previous numerical studies.

Automated summary

This paper presents novel measurement data on the dynamic soil-structure interaction of an end-bearing pile foundation. The results show that the individual pile impedances are overestimated compared to the measurements, while the interaction factors show a better agreement. Additionally, the experimental results validate the pile-soil-pile interaction results from previous numerical studies.