As an important step in effectively reducing seismic risk and the vulnerability of the city of Mobarakeh to earthquakes, a site effect microzonation Study was conducted. Seismic hazard analysis for a return period of ...As an important step in effectively reducing seismic risk and the vulnerability of the city of Mobarakeh to earthquakes, a site effect microzonation Study was conducted. Seismic hazard analysis for a return period of 475 years was carried out. Data from 10 borings was collected and analyzed, geophysical surveys were conducted and seismology and geoelectric measurements taken in more than 17 stations through out the city. The study area was divided into a grid of 500×500 m2 elements and the sub-surface ground conditions were classified into 5 representative geotechnical profiles. Electric resistivity was measured in close to 17 geotechnical boreholes and surface and sub-surface sediments were collected and analyzed. Site response analyses were carried out on each representative profile using 30 different base rock input motions. Distribution maps of site periods and peak ground acceleration and old and new texture buildings through out the city were developed, providing a useful basis for land-use planning in the city.展开更多
The site effects relating to the amplification of ground motion under earthquake loading are strongly influenced by both the subsurface soil condition and the geologic structure. In this study, for site characterizati...The site effects relating to the amplification of ground motion under earthquake loading are strongly influenced by both the subsurface soil condition and the geologic structure. In this study, for site characterization at the Imam Khomeini International Airport (IKIA) area in south of Tehran, in-situ seismic refraction tomography were carried out as a part of site investigations project, in addition geologic setting, borehole drilling, ground waters information and measurements. Based on seismic refraction studies, three layers are separable which with increasing in depth the S and P wave velocity is increased and this indicates increasing in compaction of soil and geologic materials. In the second and third separated layers, the zones with low and high seismic shear wave velocity is approximately equal, and northeast and southwest of the airport site has the low velocities, in addition to containing loose soils, highly weathered stones, and low depth to groundwater. In terms of Poisson’s ratio, the most important and key installations of airport site are located in suitable positions. According to Iranian Seismic Code, most of the lands around the airport are in class 2 and 3. It seems that a fault or a discontinuity is passed from northwest to the southeast of the study area. This site, according to geological, subsurface geophysical, and geotechnical boreholes studies, is high risk-earthquake prone.展开更多
文摘As an important step in effectively reducing seismic risk and the vulnerability of the city of Mobarakeh to earthquakes, a site effect microzonation Study was conducted. Seismic hazard analysis for a return period of 475 years was carried out. Data from 10 borings was collected and analyzed, geophysical surveys were conducted and seismology and geoelectric measurements taken in more than 17 stations through out the city. The study area was divided into a grid of 500×500 m2 elements and the sub-surface ground conditions were classified into 5 representative geotechnical profiles. Electric resistivity was measured in close to 17 geotechnical boreholes and surface and sub-surface sediments were collected and analyzed. Site response analyses were carried out on each representative profile using 30 different base rock input motions. Distribution maps of site periods and peak ground acceleration and old and new texture buildings through out the city were developed, providing a useful basis for land-use planning in the city.
文摘The site effects relating to the amplification of ground motion under earthquake loading are strongly influenced by both the subsurface soil condition and the geologic structure. In this study, for site characterization at the Imam Khomeini International Airport (IKIA) area in south of Tehran, in-situ seismic refraction tomography were carried out as a part of site investigations project, in addition geologic setting, borehole drilling, ground waters information and measurements. Based on seismic refraction studies, three layers are separable which with increasing in depth the S and P wave velocity is increased and this indicates increasing in compaction of soil and geologic materials. In the second and third separated layers, the zones with low and high seismic shear wave velocity is approximately equal, and northeast and southwest of the airport site has the low velocities, in addition to containing loose soils, highly weathered stones, and low depth to groundwater. In terms of Poisson’s ratio, the most important and key installations of airport site are located in suitable positions. According to Iranian Seismic Code, most of the lands around the airport are in class 2 and 3. It seems that a fault or a discontinuity is passed from northwest to the southeast of the study area. This site, according to geological, subsurface geophysical, and geotechnical boreholes studies, is high risk-earthquake prone.
