Lateral Loading Experiment on Buried Pipe Using Liquefied Stabilized Soil as Backfill Material for Thrust Restraint

A method for thrust restraint using liquefied stabilized soil (LSS) is proposed in this paper. LSS has been used as backfill material of pipelines recently, but it is not readily known how the bends of pipelines behave when backfilled with the LSS. We expect that the LSS is an effective backfill material against a thrust force. Model pit experiments using a model pipe having a diameter of 260 mm were carried out in order to examine the effectiveness of the LSS for the thrust restraint of a buried bend. The LSS was applied to the passive area of the model pipe and dry silica sand was used as backfill material. The model pipe was laterally loaded at a speed of 1 mm/min after backfilling to simulate the thrust force. The lateral resistance and the horizontal displacement of the model pipe were both measured. The earth pressure distributions of the passive ground were observed. In addition, numerical analyses using the distinct element methods (DEM) were carried out to simulate the model tests. The results of the model experiments showed that the lateral resistance of the bend in using the LSS was increased. It was verified that the LSS is an effective backfill material to some extent for thrust restraint. Moreover, the numerical analyses clarified the resistance mechanism of the proposed method.