Assessment of Local Site Condition on Seismic Ground Motion in Arak, Using Experimental Measurements and Numerical Model
- PDF / 2,908,969 Bytes
- 16 Pages / 595.276 x 790.866 pts Page_size
- 84 Downloads / 175 Views
RESEARCH PAPER
Assessment of Local Site Condition on Seismic Ground Motion in Arak, Using Experimental Measurements and Numerical Modeling I. Raeisizadeh1 · E. Haghshenas2 · M. Kamalian2 · S. H. Lajevardi1 Received: 3 October 2019 / Accepted: 21 January 2020 © Shiraz University 2020
Abstract In order to estimate the seismic site response of alluvial deposits in Arak, spectral analysis of microtremor data in 20 locations (in northwest–southeast and northeast–southwest sections) has been performed. Using horizontal-to-vertical spectral ratio (H/V) on the recorded data, natural periods and corresponding amplification factors of soil layers, and using Rayleigh wave inversion techniques, the thickness of the soil layers and depth of seismic bedrock were estimated. In addition, 1D numerical analyses using DEEPSOIL software and 2D modeling using PLAXIS program, linearly at low strain levels, were performed and the results were compared to experimental technique. The comparison of microtremor results with 1D and 2D numerical modeling results shows a 25% difference in NW–SE direction. This difference can be attributed to the magnitude of seismic waves in a one-dimensional and two-dimensional analysis of this study. While in the northeast–southwest directions, the results are fairly consistent indicating one-dimensional site behavior in this direction. Keywords Microtremor · H/V method · HVTFA method · Shear wave velocity profile · 1D and 2D soil response analysis
1 Introduction Arak city is relatively low risk in terms of earthquake hazards calculated in 2800 standard. Therefore, there has never been a comprehensive study on the geotechnical conditions of this area and its seismic zoning. Due to the possibility of earthquake recurrence, zoning studies in the area seem necessary, following the earthquakes occurred on January 2011 in the northwest of Arak city and southeast of Ashtian city. The local effects of the site, soil parameters and alluvial * E. Haghshenas [email protected] I. Raeisizadeh i‑raeisi92@iau‑arak.ac.ir M. Kamalian [email protected] S. H. Lajevardi sh‑lajevardi@iau‑arak.ac.ir 1
Department of Civil Engineering, Arak Branch, Islamic Azad University, Arāk, Iran
Geotechnical Engineering Research Center, International Institute of Earthquake Engineering and Seismology (IIEES), No. 26, Arghavan Street, North Dibajee, Farmanieh, Tehran, Iran
2
dynamic analysis can be studied, and adequate information on local soil conditions at the time of the next earthquake can be provided using microzoning studies (Fäh et al. 2001). Most of the obtained spectral curves have a specific peak at frequencies below 1 Hz or around it, according to the study conducted by Haghshenas et al., using H/V method in the urban area of Arak city. The low frequencies observed in different parts of the city with different geological conditions may be due to the presence of strong impedance difference in deep or the effects of sedimentary basin margins. Also, along with these natural factors, the possibility of industrial orig
Data Loading...
