The bending strains developed in an experimental shallow buried pipeline due to static and rolling wheel loads have been investigated. The instrumented pipeline, comprising eight 3.7 m lengths of 100 mm internal diameter spun iron pipe with lead-run joints, was constructed under a weak pavement. Both good and poor bedding conditions were established. Commercial vehicles having axle loads up to 10 mg were used to traffic the buried pipeline at speeds of up to 48 km/h. The measured bending strains increased linearly with axle load, the strains for any given load tending to decrease with increasing vehicle speed. Axle spacing had little effect on maximum strains in the pipeline for the range of vehicles used. Residual strains developed during backfilling and pavement construction did not vary appreciably throughout the test programme, involving some 300 axles of loading. Maximum strains were always associated with the poorly bedded pipes and under the most severe loading applied, were similar in magnitude to the maximum residual strain and small in relation to the failure strain derived from tests on sample pipes. (Author/publisher)
Abstract