Damage Ratio Prediction for Buried Pipelines Based on the Deformability of Pipelines and the Nonuniformity of Ground

Abstract

Damage susceptibility of pipelines during an earthquake bears close correlation with both the degree of “deformability” and the degree of “nonuniformity” of subsurface ground in which the pipelines are laid. A ground-block model is used to define the “deformability index” and the “nonuniformity index” in this paper; the latter is defined as a standard deviation of expected seismic displacement in a ground which is expressed as a set of ground blocks. Then the possibility of damage to a pipeline system is expressed in terms of a probability that a relative displacement between two adjoining ground blocks, which depends on the value of nonuniformity index, exceeds the value of deformability index of the pipeline. In this paper, values of nonuniformity index for various types of grounds are evaluated using damage statistics obtained during past earthquakes, and a practical method of damage ratio prediction is proposed.