DEVELOPMENT OF A STRAIN MEASUREMENT SYSTEM FOR SOILS AND ITS APPLICATION TO SAND AROUND A BURIED PIPE

概要

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A strain measurement system is developed to determine exact strain distributions in soil in model tests using an X-ray technique. This method can determine displacements and strains in soil by tracing images of small lead shot recorded on X-ray films. The lead shot are embedded in advance in soil in a lattice pattern. The reliability of the method therefore depends upon the accuracy of determining the coordinates of lead shot images. An equipment called "X-ray Film Reader" which satisfies this requirement is developed. The method has also in advantage of detecting rupture lines on X-ray films as dark curves, which represent the failure mechanism of soils, since the void ratio exceedingly increases there. As an example the method is applied to model tests to study the behaviour of sand around a buried pipe, where the adjacent sand settles. In this case the failure mechanism of sand is usually based upon the projection condition of the Marston-Spangler theory. Several interesting observations are made from the model tests that the configuration of rupture lines largely depends on the initial void ratio of backfilled sand and differs from the sliding planes assumed in the Marston-Spangler theory, and that the maximum shear strain is prominent along rupture lines recorded on X-ray films.
社団法人地盤工学会の論文
1983-09-15