Abstract
The thrust force generated by the action of internal pressure tends to move the bend of underground pipeline to the back side. This thrust force is supported by the passive earth pressure that affects the back of ground. The concrete block is commonly used at the bend to minimize the thrust.
However, the earth pressure distribution is not readily known when the pipe moves laterally in the ground. In addition, such heavy concrete block becomes a weak point during earthquake, since it is different from the behavior of the pipeline.
In this paper, model tests were carried out using a steel pit having length of 2m and the model pipes having a diameter of 90mm that was equipped with geosynthetics as the lateral anchors in order to clarify the effectiveness of this new method. In addition, similar tests were conducted using a model piece of square on the assumption of the concrete block, to compare with present design method.
As the result, it was found that the weight saving new protecting method with geosynthetics was extremely effective against thrust force. Furthermore, using results of tests having different depth of cover, the equation for estimate was suggested, considering the resistance generated by geogrid.
