STUDY ON NON-UNIFORMITY COEFFICIENT OF GROUNDS FOR EXAMINING SEISMIC PERFORMANCE OF WATER PIPES IN CONSIDERATION OF THE BOUNDARY CONDITIONS IN MICROTOPOGRAPHY CLASSIFICATIONS

Abstract

 High damage ratios of embedded pipes are seen in microtopography boundaries in a microtopography classification map. Moreover, the past studies have revealed that ground with high non-uniformity is vulnerable to earthquakes. Therefore, it has become necessary to examine earthquake-proofing performance of embedded pipes for which non-uniformity (area where ground constitutions and hardness and softness vary) of ground is considered. The non-uniformity coefficient is defined in "the seismic methods 2009 edition guideline description waterworks". For this non-uniformity coefficient, the authors calculated ground strain by static and dynamic analyses based on types and boundary conditions of microtopography using data of water pipes damaged by Niigata Chuetsu Earthquake in 2004 and Niigata Chuetsu Offshore Earthquake in 2007, a microtopography classification map and ground data. Their results were compared and the non-uniformity coefficient for which types and boundary conditions of microtopography were considered was examined.