Load Transfer Analyses of Buried Pipe in Different Backfills

Abstract

Nonlinear finite-element analyses have been carried out to assess the effects of different trench backfill materials, pipe burial depths, and pipe materials on the amount of traffic load transferred to buried pipe. The analyses show that the use of trench backfills such as controlled low strength material (CLSM) instead of traditional materials such as sand and clay, results in significantly reduced stresses in polyvinyl chloride (PVC) pipe under traffic loading. This finding is in agreement with recent truck load tests carried out in the City of Edmonton, where strains were monitored on buried PVC water mains. The protection of buried pipes under or in CLSM backfill from traffic loading becomes more significant with the decrease in pipe burial depth and stiffness. The reasons behind the difference in load transfer between the traditional backfills and CLSM are the high elastic modulus and strength of CLSM, as well as uniform load transfer along the longitudinal axis of the pipe.