S. Hashemi Tabatabaei; A. S. Salamat; A. Mohamadi
Abstract
Seismic site characterization studies are carried out in earthquake- prone areas. In these studies seismic design parameters are chosen based on engineering geological and geotechnical characteristics of the site. Site classification is addressed in various building codes. Codes define various methods ...
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Seismic site characterization studies are carried out in earthquake- prone areas. In these studies seismic design parameters are chosen based on engineering geological and geotechnical characteristics of the site. Site classification is addressed in various building codes. Codes define various methods for soil classification such as measurement of average shear wave velocity up to 30 meters depth. This paper present a part of the seismic geotechnical microzonation study of Shiraz city based on seismic data for soil classification. This method, measures the travel times of multiple elastic waves along the interface of layers having different velocities. In this study a seismograph with an array of 24 geophones and 3.75m intervals was used. The shear wave velocity distribution estimated for 3 different seismic layers. Seismic bedrock was defined as layer for which shear wave velocity is more than 750 m/s. Depth of seismic bedrock was estimated to vary about 1 to 29m.The average shear wave velocity up to depth of 30 m ranges about 375 to 1253m/s. Based on the results soil profile in Shiraz were classified and compared with the Standard No. 2800 and Eurocode-08. The result indicated that Shiraz city can be placed in "site class I" and "site class B, E and A" respectively. The study revealed that Standard No. 2800 site classification should be modified.
M. Rajabi; B. Bohloli; M. Mohammadinia; E. Gholampour Ahangar
Abstract
The shear and compressional wave velocities (Vs and Vp, respectively) have many applications in petrophysical, geophysical and geomechanical studies. Vp is very easily obtained from sonic logs that are available in most of oil and gas wells, but some wells (especially old wells) may not have Vs data. ...
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The shear and compressional wave velocities (Vs and Vp, respectively) have many applications in petrophysical, geophysical and geomechanical studies. Vp is very easily obtained from sonic logs that are available in most of oil and gas wells, but some wells (especially old wells) may not have Vs data. In this study Vs was predicted from porosity well log data (neutron, density and sonic) using fuzzy logic and neuro-fuzzy techniques. For this purpose a total of 3910 data points from Sarvak carbonate reservoir which have Vs and porosity log data were utilized. These data were divided into two parts, one part included 2046 data points used for constructing models and the other part included 1864 data points used for testing models. The results show that fuzzy logic and neuro-fuzzy techniques were useful methods for prediction of Vs in this carbonate oil reservoir.
