Effects of Tamping and Pavement Breaking on Round Conduit

An extensive investigation to establish the minimum strength requirements for round conduit, based upon the effect of static loads has been reported by one of the authors. It was shown that the minimum required strength depends on the magnitude of the load applied at the surface of the fill, the properties of the backfill material, the height of the backfill over the conduit, the trench width and the bedding condition. The increasing use of heavy-duty power-activated equipment for tamping backfill in trenches and for breaking pavement has made it. necessary to expand this investigation in order to determine the effect of dynamic forces on underground conduit and pipes. This study is intended to show the conditions under which tamping or pavement-breaking equipment may be used without damaging underground conduit that has the minimum strength required to withstand static loads. External loads acting upon the conduit produce circumferential bending moments in the conduit wall. The magnitude and distribution of these bending moments caused by the operation of tamping and pavement breaking machinery have been determined in tests conducted recently at the Outside Plant Development Laboratory, Chester, New 1