The Effect of Liquefied Stabilized Soil with Geosynthetics against Thrust Force of Buried Bend

摘要

Thrust force is generated at a bend of pipeline due to internal water pressure. Commonly, the thrust force is resisted by the passive resistance acting on the bend. In Japanese current design (M.A.F.F. 1998), the passive resistance is calculated based on Rankine's earth pressure theory.rnIn this paper, new backfill methods using geogrid, gravel and liquefied stabilized soil were proposed. In the new backfill methods, geogrids are employed at the passive area in front of the bend in order to increase the passive resistance against thrust force. In addition, gravel or liquefied stabilized soil are used for the reinforcement of the passive area. In order to clarify the effect of these proposed methods, lateral loading experiments were carried out using a model pipe having a diameter of 114 mm. The model pipe was backfilled in dry sand at the depth of 114 mm. After backfilling, the model pipe was laterally loaded at a speed of 0.5 mm/min. using a jack.rnFrom the experimental results, it was proved that the passive resistance in case of reinforcement was larger than that in case of non-reinforcement. In addition, it was found that the passive resistance was influenced by the arrangement of geogrid. Furthermore, it was confirmed that the passive resistance was considerably increased in case of using liquefied stabilized soil with geogrid.