Abstract:
This thesis focuses on the damage analysis of buried gas supply pipeline of Dhaka City
subject to earthquake effects. Damage prediction of gas pipelines due to earthquake involves
seismic microzonation of Dhaka city and determination of the length of water supply
pipeline. In this process already developed seismic microzonation map of Dhaka city is used
and the available map of gas supply pipeline network of “TITAS gas Transmission and
Distribution Company Ltd” is digitized to get the length of pipelines with the help of GIS
software.
On the basis of intensity the whole Dhaka city has been divided into three different zones.
Out of total area of 135 sq.km 88 sq.km is (65%) of intensity VIII, 39 sq.km is (29%) of
intensity IX and remaining 9 sq.km is (6%) of intensity X. From the digitized pipeline
network, based on 1988 “TITAS gas Transmission and Distribution Company Ltd”, the
length of 20mm, 25mm, 50mm, 75mm, 100mm, 150mm, 200mm, 250mm and 300mm
diameter pipe is found to be 11.3 km, 121.28 km, 175.16 km, 40.69 km, 28.35 km, 28.52 km,
42 km, 1.5 km, and 3.49 km respectively. Again from the intensity based pipeline network it
is found that 376 km pipe falls in the zone of intensity VIII, 67.31 km falls in the zone of
intensity IX and 22.23 km falls in the zone of intensity X irrespective of pipe diameter. A
selection step is followed to estimate peak ground acceleration (PGA) and peak ground
velocity (PGV) to determine the pipeline damage rate. Existing empirical relations based on
peak ground acceleration such as Katayama (1975), Isoyama and Katayama (1982),
O’Rourke (1998) and Isoyama (2000) for the prediction of earthquake-induced pipeline
damage are reviewed. Similarly empirical relations based on peak ground velocity such as
Eidinger et al. (1995, 1998), O’Rourke and Ayla (1993), Isoyama (2000) and O’Rourke
(2001) also reviewed. Finally using above relations and selected peak ground acceleration
and peak ground velocity damage rate of pipelines is determined.
Pipeline damage rate is expressed in number of repairs per unit length of pipe. In case of
PGA based analysis total number of repairs for all intensities is 97 within a total pipe length
of 465 km. Out of which 24 numbers of repairs required for 376 km pipelines, 28 numbers of
repairs required for 67.31 km pipelines and 45 numbers of repairs for 22.23 km. For PGV
base analysis total number of repairs for all intensities is 182 within total pipe length of 465
km. Out of which 87 numbers of repairs required for 376 km pipelines, 50 numbers of repairs
required for 67.31 km pipelines and 45 numbers of repairs for 22.23 km.
