Large Scale Experiments on Lightweight Thrust Restraint for Buried Bend under Internal Pressure

Abstract

In bends, unbalanced force, which is called thrust force, is generated. Generally a concrete block is installed at the bend to provide the lateral resistance. However, the heavy concrete block is weak point in earthquake. In our previous study, a lightweight thrust restraint using geogrid was suggested and the effect was proved by laboratory small tests. In the present study, the large-scale tests for the new method were carried out in a large pit (8.4m×5.4m×4m), using a pipe bend having a diameter 300mm. As the results the lateral displacement of the bend was reduced by the proposed method. In addition, it was revealed that the effect was depended on the stiffness, length and installation of geogrid.