A simple 3-dimensional photoelastic model test was devised that would yield data which is compatible with previously reported unlined elliptical tunnel under line loading. The details are outlined of the three-dimensional photoelastic stress freezing tests that were performed on lightly loaded models in a controlled circulation oven. The studies found that under the action of a concentrated surface load, only a relatively small region of the upper portion of the tunnel is subject to high tensile hoop stresses while the compression hoop stresses are distributed more uniformly with their maximum values at about 45 deg. on both sides of the vertical semi axis. In addition to obvious differences because of the attenuation of the concentrated load effect away from the point of load application, the distribution of hoop stresses in the section directly under the loading was also shown to differ significantly. It is concluded that the stress distribution found from a 2-dimensional physical or numericalmodel under an assumed line loading, can only give a coarse approximation of the true effect of a concentrated point load.

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  • Accession Number: 00148203
  • Record Type: Publication
  • Report/Paper Numbers: ASCE #12536
  • Files: TRIS
  • Created Date: Mar 15 1977 12:00AM