TORSIONAL RESPONSE OF PILES-DISCUSSION

Short-term torsional load tests were performed upon model cylindrical piles embedded in soils with a constant shear modulus (clay) and shear moduli increasing linearly with depth (sand). In the 3 cases described here, excellent agreement is observed up to about 40 percent of the failure torque, whereafter greater rotation at corresponding levels of torque is evident in the measured data. The deviation in the high torque range is thought to be caused by a progressive failure beginning at the top of the model piles. Failure rotation is achieved near the top of the pile at a level of torque well below the failure torque. Additional rotation is believed to produce a decrease in interfacial pile-soil stress near the top while continuing to mobilize additional stresses farther down. Studies have shown that the soil response to torsional load bears a nonlinear relationship. A graphic figure is used to represent, the practical upper limits to anticipated deviations from response predicted by the authors. A second discusser compares the measured torsion strain indicated by field torsion tests, with that calculated based on the author's procedures. Field soil conditions were rather variable, ranging from clayey silt to clayey sand and gravel but the measured ultimate average torsion resistance was 550 psf. Comments are also made regarding shear moduli values, the torsional strain at the top of the pipe, and measured twist. The author's precedures promise practical solutions to a relatively wide range of field conditions and pile configurations.

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  • Accession Number: 00141314
  • Record Type: Publication
  • Report/Paper Numbers: ASCE #11629 Proceeding
  • Files: TRIS
  • Created Date: Oct 26 1976 12:00AM