A plain steel pipe with a diameter of 762 mm was buried in the field at depths of 0.3, 0.6, and 1.0 m to investigate the differences in pipe behavior under soil compaction and external load. The study reveals that soil compaction causes the pipe deforming into a vertical ellipse. Contrary to that, truck load acting on ground vertically compressed the pipe ring, especially at the upper part. The strains generated by a perpendicularly parked truck are higher than those when the truck is parallel to the pipe. Both during the installation procedure and under external truck load, the highest strains are measured at the pipe crown, and the circumferential strains are higher than those measured in the longitudinal direction. The measured pipe strains increase linearly with increasing axle load up to 86.75 kN. A nonlinear relation is observed between the measured pipe strain and the cover depth. Existing equations are evaluated in predicting the maximum circumferential stress under soil self-weight and external truck load. Watkins's method predicts the pipe stresses comparable to those calculated based on pipe strains measured right underneath the tire center.
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