Local Site Effects Evaluation for Gyobyu Lifeline using Microtremor Measurements

Abstract

Gyobyu pipeline, one of the water supply network system of Yangon region, since this pipeline was constructed in 1940, any seismic design was not considered. During the recent earthquake, 13.3.2017 Taikkyi Earthquake, Magnitude 5.1, pipe supports damage were observed at many locations in the Gyopyu reservoir area. Local site effect is one of the most important aspects in the assessment of seismic hazard and many of the destructive earthquakes in the past have shown that local site conditions have major effects on the ground shaking. In this study, the recorded ambient noise along pipeline was used to compute the H/V spectral ratio and then to evaluate the local site effect of the area. The HVSR analysis has been carried out using Cygwin Terminal Software. The predominant frequency (F) ranges between 1.17 to 4.41Hz and amplification factor (A) varies from 1.07 to 3.25. The vulnerability index (Kg) having values ranging from 0.44 to 7.9. The vulnerability index (Kg) is indicated the soil damage level due to ground motions.