Press-in piling, known as pile jacking, is a relatively new technique for foundation construction. Jacked piles are gaining popularity because they are free from vibration and noise during installation. In this thesis, about 100 cases of static loading tests were collected for compiling a database for jacked piles. The data collected were classified according to different types of founding soil and pile. The relationships between final jacking load and ultimate pile capacity were also investigated for different types of founding soil. ₀...[ Read more ]

Press-in piling, known as pile jacking, is a relatively new technique for foundation construction. Jacked piles are gaining popularity because they are free from vibration and noise during installation. In this thesis, about 100 cases of static loading tests were collected for compiling a database for jacked piles. The data collected were classified according to different types of founding soil and pile. The relationships between final jacking load and ultimate pile capacity were also investigated for different types of founding soil.

Time-dependent effects for jacked piles were investigated in the research. During pile installation pauses, the pile capacity and stiffness generally increase by about 30% per log-time cycle when the reference time t₀ is taken as 1 hour. The change in pile capacity and stiffness with time after pile installation was also studied. Capacity setup was observed in clay and sand, while relaxation was observed in silty sand. The pile stiffness was found to increase with time after pile installation. Behaviour of driven piles and jacked piles was compared in terms of changes in capacity with time. It was found that the setup effect was more significant in driven piles than in jacked piles.

From field and centrifugal test results, when a pile was subjected to a low number of loading cycles, a decrease in the toe resistance occurred; meaning a greater portion of load was taken by the pile shaft. However, a decrease in the shaft resistance occurred when the pile was subjected to a larger number of loading cycles. Cumulative pile settlement was found to increase with a declining rate as the number of loading cycles increased. The effect of cyclic loading on the pile stiffness was found to increase with the number of final jacking cycles. Considering the pros and cons of the cyclic load effects, three jacking cycles was recommended for pile construction.