Publication Abstract

Proceedings - Fourth International Conference - Piling and Deep Foundations, 1991, Stresa, Italy, (DFI)

Short and long term shaft resistance of driven instrumented pile in soft clay
M.M. Hamza; Suez Canal University, Egypt

A special testing program was carried out for a composite "Lacor" type concrete pile of 36 meters long, 35 cm diameter, driven through soft, very soft and medium consistency clay, to finally rest in dense sand at Damietta power plant site, Egypt. The pile was instrumented at six levels with two strain gauges at each level, capable of sensing and recording the value of the pile load at the installed level. The measurement allowed the field load transfer profile and shaft resistance to be determined for static loading condition. The instrumented pile was statically tested twice, for short and long term evaluation; one month and eighteen months after driving. Analysis and comparison of short and long term load transfer profiles indicated the time effect on increasing shaft resistance after pile driving. The long term pile shaft resistance in the soft clay was 2.75 times the short term value. The measured values were used to test the theoretical prediction of the increased undrained shear strength, by Wroth et al. (1979), and good agreement is found. To the author's knowledge, no similar field measurements of delayed shaft resistance were available for comparison.

 article #521; publication #37 (IC-1991-IT)