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EN
Liquefaction which is one of the most destructive ground deformations occurs during an earthquake in saturated or partially saturated silty and sandy soils, which may cause serious damages such as settlement and tilting of structures due to shear strength loss of soils. Standard (SPT) and cone (CPT) penetration tests as well as the shear wave velocity (Vs)-based methods are commonly used for the determination of liquefaction potential. In this research, it was aimed to compare the SPT and Vs-based liquefaction analysis methods by generating different earthquake scenarios. Accordingly, the Erciş residential area, which was mostly affected by the 2011 Van earthquake (Mw = 7.1), was chosen as the model site. Erciş (Van, Turkey) and its surroundings settle on an alluvial plain which consists of silty and sandy layers with shallow groundwater level. Moreover, Çaldıran, Erciş–Kocapınar and Van Fault Zones are the major seismic sources of the region which have a significant potential of producing large magnitude earthquakes. After liquefaction assessments, the liquefaction potential in the western part of the region and in the coastal regions nearby the Lake Van is found to be higher than the other locations. Thus, it can be stated that the soil tightness and groundwater level dominantly control the liquefaction potential. In addition, the lateral spreading and sand boiling spots observed after the 23rd October 2011 Van earthquake overlap the scenario boundaries predicted in this study. Eventually, the use of Vs-based liquefaction analysis in collaboration with the SPT results is quite advantageous to assess the rate of liquefaction in a specific area.
EN
This article presents the results of seismic shear wave velocity (VS) measurements using the CSWS/SAWS (Continuous Surface Wave System/Spectral Analysis of Surface Waves) and SDMT (seismic flat dilatometer) methods, as well as BET (Bender Elements Test), on an experimental test site (and samples taken from it). The test site, a geologically relatively uniform alluvial sand formation area, was carefully chosen and checked for uniformity by means of drillings and soundings. The research aimed to determine how results from indirect, non-invasive surface geophysical tests (SASW and CSWS) correspond with those from SDMT penetration tests as well as the BET laboratory seismic method, and how some methodological aspects can influence them. Different wave sources and frequency were examined as the main factors for interpretation. The influence of other examined factors is also discussed.
EN
Shear and compressional wave velocities, coupled with other petrophysical data, are very important for hydrocarbon reservoir characterization. In situ shear wave velocity (Vs) is measured by some sonic logging tools. Shear velocity coupled with compressional velocity is vitally important in determining geomechanical parameters, identifying the lithology, mud weight design, hydraulic fracturing, geophysical studies such as VSP, etc. In this paper, a correlation between compressional and shear wave velocity is obtained for Gachsaran formation in Maroon oil field. Real data were used to examine the accuracy of the prediction equation. Moreover, the genetic algorithm was used to obtain the optimal value for constants of the suggested equation. Furthermore, artificial neural network was used to inspect the reliability of this method. These investigations verify the notion that the suggested equation could be considered as an efficient, fast, and cost-effective method for predicting Vs from Vp.
EN
Formation’s properties can be estimated indirectly using joint analysis of compressional and shear wave velocities. Shear wave data is not usually acquired during well logging, which is most likely for cost saving purposes. Even if shear data is available, the logging programs provide only sparsely sampled one-dimensional measurements: this information is inadequate to estimate reservoir rock properties. Thus, if the shear wave data can be obtained using seismic methods, the results can be used across the field to estimate reservoir properties. The aim of this paper is to use seismic attributes for prediction of shear wave velocity in a field located in southern part of Iran. Independent component analysis (ICA) was used to select the most relevant attributes to shear velocity data. Considering the nonlinear relationship between seismic attributes and shear wave velocity, multi-layer feed forward neural network was used for prediction of shear wave velocity and promising results were presented.
PL
W artykule zaprezentowano wyniki sondowań sejsmicznych typu SCPT, przeprowadzonych w iłach warwowych okolic Radzymina. Badania wykonano za pomocą aparatury SCPTu firmy Geotech. Rezultaty pomiarów poddano analizie statystycznej w celu opracowania zależności korelacyjnej prędkości fali ścinającej Vs od oporu na stożku qt. Analizy odniesiono do obowiązujących w światowych badaniach związków korelacyjnych wiążących prędkość fali ścinającej z parametrami penetracji sondowań statycznych.
EN
This paper presents a method of seismic piezocone tests. It presents a brief description of the SCPTu Geotech testing apparatus and testing methodology. The results obtained at Mokre test site from in situ measurements of seismic wave velocity in varved clays are presented and analyzed. Local statistical correlations between shear wave velocity Vs and cone resistance q1 are presented in this paper.
EN
Based on a variety of case histories of site investigations, including extensive bore-hole data, laboratory testing and geophysical prospecting, an empirical formulation is proposed for the rapid determination of allowable bearing capacity of shallow foundations. The proposed expression consistently corroborates the results of the classical theory and is proven to be rapid and reliable. It consists of only two soil parameters, namely, the in situ measured shear wave velocity, and the unit weight. The unit weight may be also determined with sufficient accuracy by means of another empirical expression using the P-wave velocity. It is indicated that once the shear and P-wave velocities are measured in situ by an appropriate geophysical survey, the allowable bearing capacity as well as the coefficient of subgrade reaction and many other elasticity parameters may be determined rapidly and reliably through a single step operation, not only for soils, but also for rock formations. Such an innovative approach, using the seismic wave velocities only, is considerably cost- and time-saving in practice.
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