Abstract
Many kinds of pipelines are buried underground in a city and the earthquake often brings the damage to these pipelines. The purpose of the present study is to propose the decision method of the optimum kind of pipe (i.e. the optimum material of pipe) against the earthquake damage by using the reliability theory. This paper firstly describes the actual conditions of the earthquake damage of pipelines and the results of the factorial analysis in relation to the type and state of the ground and the materials of pipes forming a pipeline. As a result, it is shown that the earthquake damage of pipelines is strongly influenced by N-value of a surface layer up to 5 m in depth and the kind of pipe. Secondly the probability of failure of pipelines are calculated by using the past data of the actual damage and the decision method of the optimum kind of pipe is discussed with many numerical examples. The numerical study gives the results which agree with the common-sense presumption.
