Determination of ground structure using microtremor array method
Loading...
Date
2018-06
Authors
Yi Ben, Cheah
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Ground structure characteristic is an important parameter in seismic site effect
evaluation for earthquake structural design. Many geophysical methods can be used to
estimate ground structure. The best field measurement option that requires least field
effort and yet producing accurate estimation is the main concern of this study. This study
applies microtremor array observation method to investigate the accuracy of VS profile
estimated using Spatial Autocorrelation (SPAC) and Centerless Circular Array (CCA)
methods of various array radii. Based on VS profile obtained, the effect of considering
sediment thickness of more than 30m on ground classification is investigated.
Microtremor array observation was conducted at a total of nine sites in Kuala Lumpur
and Penang with large (10m radius and above), medium (5m radius) and small (1m
radius) array. When using SPAC method, larger array gives better VS profile estimation.
When using CCA method, medium array gives better estimation among three array sizes.
CCA method gives better estimation as compared to SPAC method when medium array
is used in observation. Thus, CCA method is more favourable in term of fieldwork
efficiency. Out of five sites with sediment thickness more than 30m, four sites exhibit
ground type changes by reducing one to two classes and the other one remains
unchanged. Although the ground type remains unchanged, but the acceleration response
increases. These changes in ground type have affected low to medium rise buildings
within the fundamental periods of 0.1s to 1.0s significantly because the acceleration
response increases drastically when sediment thickness more than 30m is considered.