Laboratory Observation of the Response of a Buried Pipeline to Freezing Rubber-Sand Backfill

This paper addresses the potential use of granulated rubber as backfill material for buried pipelines in cold regions. An experiment on a laboratory scale buried pipe was conducted to evaluate the pipe-backfill interaction upon freezing. Two backfill materials were employed. In Case 1, sand was used as backfill material. In Case 2, granulated rubber was mixed with sand. Induced circumferential and longitudinal strains along the pipe were measured with movement of the freezing front into the backfill and an estimate of the freezing soil pressure was obtained based on the measured pipe strain. Experimental results showed that the behavior of the buried pipe was influenced by the progression of the freezing front and type of backfill material. Cold temperatures advanced faster into the sand backfill compared to the rubber-sand backfill due to the good thermal characteristics of rubber. Circumferential strains increased in both backfills indicating the development of freezing soil pressure in the backfill. Dominant vertical compressive strains were observed at 0 degrees and 180 degrees in both backfills. A significant reduction in strain and pressure exerted on the pipe upon freezing in the rubber-sand backfill was confirmed and the application of rubber mixed with sand as backfill material is possible.