Some Pile Loading Tests in Stiff Clay

Abstract

Loading tests on two timber piles and a Franki pile, embedded principally in a stiff clay, were carried out. Analysis of the results appear to indicate that the adhesion of the piles is the fully mobilized undrained shear strength of the clay. Reasons for this apparent anomaly with data reported in the literature are suggested.Pore water pressures set up in the soil adjacent to the piles during load testing were very small and calculations in terms of effective stresses, indicated that the ratio of horizontal to vertical effective stress at failure is approximately 1.2.

The shaft resistance of axially loaded piles in clay

“…Measurements of pore-pressure changes during the loading of displacement piles have also been reported by Massarsch, Broms and Sundquist(1975), by Airhart, Coyle, Hirsch and Buchanan (1969) and by Lo and Stermac (1964). Table 2.1 summarises the available measurements of pore-pressure changes.…”

“…Lo and Stermac (1964), Orrjie and and Broms (1967), and Stermac, Selby and Devata (1969). The general conclusion is that the clay around timber piles consolidates the fastest, and that around steel piles the slowest.…”

“…Typical measurements range between 0.2 and 0.5 times the initial in situ undrained shear strength in triaxial compression, C^ ^ (e.g. Lo and Stermac (1964), and Clark and Meyerhof (1972 ,a), and Meyerhof (1976)). On the other hand, measurements obtained at the pile face are usually higher, and values up to 1.5 C^ ^ have been recorded along piles in sensitive clays (e.g.…”