Model test studies on soil restraint to pipelines buried in sand

The buckling of submarine pipelines may occur due to the action of axial soil frictional force caused by relative movement of soil and pipeline, which is induced by the thermal and internal pressure. The likelihood of occurrence of this buckling phenomenon is largely determined by the capability of the soil to resist pipeline movements. A series of large-scale model tests were carried out to facilitate the establishment of substantial data base for a variety of burial pipeline topologies. Results show that the soil resistance depends on the pipe diameters and the depth of cover. According to the uplift test results, the force-displacement topologies with smaller depth of cover are greatly different from those with larger depth of cover. The results of the lateral sliding and axial pull out tests show that the soil resistance initially increases before a peak value is reached and then keeps the same level. For the same covered depth, the lateral soil resistance is more than twice that for uplift.