الفهرس | Only 14 pages are availabe for public view |
Abstract Although the area of Cairo is not a place of high seismic hazard compared to other parts in Egypt (e.g., Northern Red Sea, Gulf of Suez, and Gulf of Aqaba), it may be a place of high seismic risk or high probability of seismic losses. This is may be attributed to the high population density and the presence of many cultural, economic, and political centers in the city of Cairo. In addition, most of the buildings and lifelines do not follow anti-earthquake design codes, especially those found in some localized rural communities. It is well known that near-surface geological conditions strongly influence earthquake ground motion at a particular site. The objective of this work is to analyze the influence of local geology in the southern part of the city of Cairo on earthquake ground motion and preliminary estimation of site classification scheme and strong motion modeling for the purposes of seismic design for this heavily populated area. Boreholes data, which are available from 36 sites in the study area, were used to investigate the lateral and vertical changes of the characteristics of the subsurface layers. A shallow seismic refraction survey was carried out at 11 sites in the study area in order to estimate seismic velocities (Vp and Vs) and to detect the shallow ground model. Ambient vibrations were recorded at three arrays in the investigated area in order to obtain the shear-wave velocity profile for both shallow and deep sedimentary layers. The frequency-wavenumber (f-k) method was used to derive the dispersion curves from the raw signals. The resulted dispersion curves were inverted using the neighbourhood algorithm to obtain the Vs and Vp velocity profiles at the measured sites. The Vs and Vp obtained from seismic refraction and ambient vibrations array were used in determination of the geotechnical parameters and dynamic characteristics for the shallow sedimentary layers, which are of great interest in civil engineering applications. Site classification for the investigated area was performed using the scheme accepted in the European building code (Eurocode 8), which is based on the average shearwave velocity for the upper 30 meters of the soil column (VS, 30), as well as the value of standard penetration test NSPT (available from boreholes data). Also, the information on groundwater level, which is available from boreholes data, was used to Abstract |