DAMAGE RATION PREDICTION FOR BURIED PIPELINES BASED ON THE DEFORMABILITY OF PIPELINES AND THE NONUNIFORMITY OF GROUND

Damage susceptibility of pipelines during an earthquake bears close co rrelation 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'' a nd the ''nonuniformity index'' in this paper; the latter is defined as a standard deviation of expected seismic displacement in a ground whi ch is expressed as a set of ground blocks. Then the possibility of dam age to a pipeline system is expressed in terms of a probability that a relative displacement between two adjoining ground blocks, which depe nds on the value of nonuniformity index, exceeds the value of deformab ility index of the pipeline. In this paper, values of nonuniformity in dex for various types of grounds are evaluated using damage statistics obtained during past earthquakes, and a practical method of damage ra tio prediction is proposed.