Earthquake hazard analysis for the city of Evansville, Indiana

The proximity of Evansville to the Wabash Valley fault zone and the New Madrid seismic zone exposes the area to 2 potential earthquake-related hazards: soil liquefaction and site amplification. Engineering soil data were examined and various methodologies were employed to evaluate earthquake hazards. The input ground motion parameters for liquefaction and site response analyses were determined through seismic hazard analysis. The computed maximum-magnitude earthquakes are m\sb{\rm b} = 6.9 and m\sb{\rm b} = 7.4 for the Wabash Valley fault zone and the New Madrid seismic zone, respectively. The peak horizontal ground accelerations of 0.066g, 0.133g, and 0.178g were computed (for bedrock) for the return periods of 100, 500, and 1,000 years, respectively. Four liquefaction evaluation procedures, 2 SPT- and 2 CPT-based, developed based on Western America and Japanese data, were employed. Three of these methods indicated good agreement in the results. The fourth method based on q\sb{\rm c}/N\sb{60} ratio was further analyzed by modifying the q\sb{\rm c}/N\sb{60} ratios with respect to the Evansville data. About 50 to 60% of the layers studied were found liquefiable. New Madrid seismic zone had the greater influence on the liquefiability of the layers. Liquefaction Potential Index results show that 50% of the layers have very high risk of liquefaction (LPI $\u3e$ 15). Threshold ground acceleration values for liquefaction were computed using the strain approach based on the shear wave velocity data. The results indicate that, when compared with the stress approach, the strain approach overestimates the threshold ground accelerations. Site response analysis was performed for 21 sites using the worst case and reasonable case scenario earthquakes in both seismic zones. The input time histories used were the records of the 1988 Saguenay, Canada earthquake because there was no earthquake data at bedrock for a sizable earthquake in Central North America. Results indicate that amplification ratios due to earthquakes generated in the New Madrid seismic zone are about twice as high as those caused by the earthquakes originating in the Wabash Valley fault zone. Regardless of the magnitude and the location of the input earthquake, the majority of clay sites showed higher amplification ratios than did the alluvial sand sites

perspective

For Anatolian earthquakes, there are insufficient strong motion data from rock sites to model an attenuation relationship for Turkey. This necessitates the use of records from soil sites, which are significantly affected by amplification. In order to include soil site data in the attenuation analyses, boreholes were drilled at 64 recording stations on soil sites. After removing the effects of soil amplification, rock site and soil site data were combined to establish an attenuation relationship. Various models were tested through regression analyses using moment magnitude, epicentral distance and threshold peak horizontal ground acceleration. A new attenuation relationship is modeled for Turkey

Integrated use of hydrochemistry and resistivity methods in groundwater contamination caused by a recently closed solid waste site

In order to investigate the groundwater ies aimed at defining the spatial contamination by solid waste disposal using both ies aimed at defining the spatial hydrochemical and geophysical methods, the Halkali (Istanbul) solid waste disposal site which was closed in 1994 was investigated. The disposal site lies on a ridge between two valleys filed with alluvium. A total of six boreholes were drilled on two lines across the Menekse valley adjacent to the Halkali site. Groundwater samples collected from these boreholes were analyzed for various contaminant parameters. The results indicate that TDS and chloride concentrations decrease horizontally away from the waste site whereas they increase with depth. Electrical soundings carried out at 12 locations yielded high resistivity values at the upstream part of Menekse valley while lower values were obtained from the locations near the leachate seepage points

Investigation of the effect of grain size on liquefaction potential of sands

WOS: 000513583200006Due to the permanent damage to structures during earthquakes, soil liquefaction is an important issue in geotechnical earthquake engineering that needs to be investigated. Typical examples of soil liquefaction have been observed in many earthquakes, particularly in Alaska, Niigata (1964), San Fernando (1971), Loma Prieta (1989), Kobe (1995) and Izmit (1999) earthquakes. In this study, liquefaction behavior of uniform sands of different grain sizes was investigated by using the energy-based method. For this purpose, a total of 36 deformation-controlled tests were conducted on water-saturated samples in undrained conditions by using the cyclic simple shear test method and considering the relative density, effective stress and mean grain size parameters that affect the cumulative liquefaction energy. The results showed that as the mean grain size decreases, the liquefaction potential of the sand increases. In addition, with increasing effective stress and relative density, the resistance of sand against liquefaction decreases. Multiple regression analysis was performed on the test results and separate correlations were proposed for the samples with mean grain size of 0.11-0.26 mm and for the ones with 0.45-0.85 mm. The recommended relationships were compared to the ones existing in the literature and compatible results were obtained

The effect of the pH of the testing liquid on the slake durability of gypsum

It is known that foundation problems are caused by the dissolution of gypsum due to both chemical and mechanical processes. In order to investigate the combined effect of physico-chemical agents on the erodability of gypsum, a series of slake durability tests were carried out on eight different types of gypsum using testing solutions with different pH values. XRD, chemical and petrographical analyses, and basic strength tests such as unconfined compression, Brazilian tensile, and point load were performed on the eight rock types. The slake durability results ranged from medium to very high under the different pH conditions but it was concluded that the slake durability of gypsum is independent of the pH of the testing solution. Mineralogical composition and fabric are considered to have a greater influence on the slake durability of gypsum. © Springer-Verlag 2005

TERS EKSTRÜZYON DENEYİNİN İKİ KIVAM LİMİTİNİ BELİRLEMEK ÜZERE YENİDEN DEĞERLENDİRİLMESİ

Likit limit (LL) ve plastik limit (PL) ince taneli zeminlerde çok sık kullanılan özelliklerdendir. Bunlar zeminlerin sınıflandırılmasının dışında birçok mühendislik özelliklerinin deneştirilmesinde de kullanılmaktadır. Bu nedenle, Atterberg tarafından ilk kez 1911 yılında ortaya konmasını takiben birçok araştırmaya konu edilmiştir. Mekanizmaları çok sayıda standart ile belirlenmiş ve uzun süredir kullanılıyor olmasına rağmen, yapısında var olan bazı belirsizlikler nedeniyle çokça da eleştirilmiştir. Casagrande tası ve nodül yuvarlama metotları yerine daha uygun başka bir test metodu bulabilmek için çok çalışma yapılmıştır. Bu çalışmaların bir kısmı, ilgili iki özellik göstergesini birlikte belirleyecek tek bir yöntem bulmaya yönelik olmuştur. Yakın geçmişte ters ekstrüzyon test yöntemi jeoteknikte kullanılmaya başlanmıştır. Bu yöntemin LL, PL ve hatta büzülme limitlerinin (SL) belirlenmesinde kullanılabileceği ortaya konmuştur. Bu çalışmanın amacı ters ekstrüzyon yönteminin daha ileri aşamada rafine edilerek LL ve PL’yi belirlemedeki becerisini yeni bir değerlendirmeye tabi tutmaya yöneliktir. Bu amaçla farklı plastiklik derecesine sahip 70 ince zemin örneği kullanılmıştır. Aynı şekilde düşen koni ve nodül yuvarlama metodları da LL ve PL’nin belirlenmesinde kullanılmıştır. Ters ekstrüzyon testi her zemin numunesi için 5 farklı su içeriğinde yapılmıştır. Grafiklerde ekstrüzyon basıncı su içeriğine karşı yerleş- tirilmiş; veri çiftlerine uygun eğri uygulanmıştır. Buradan hareketle eğrinin y eksenini kestiği yeri (a katsayısı) ve eğimi (b katsayısı) belirlenmiştir. Böylece, daha önceki çalışmacıların yaptğı gibi ters ekstrüzyon katsayıları kullanılarak LL ve PL ile ilgili temsilci ekstrüzyon basınçları belirlenmeye çalışılmıştır. Ters ekstrüzyon basıncı kullanılarak LL ve PL’nin belirlenmesi çalışmasının sonucu pek ümit verici olmamıştır. Daha önceki yaklaşım önerilerinden farklı olarak, ters ekstrüzyon katsayıları (yani, a ve b), yaygın olarak kullanılan düşen koni ve nodül yuvarlama metotları kullanılarak ters ekstrüzyon parametrelerinin fonksiyonu olarak bulunan LL ve PL değerleri ile birlikte çoklu regresyon analizine tabi tutulmuştur. Bu çalışma ile ters ekstrüzyon katsayıları kullanılarak LL ve PL’nin hassas olarak bulunacağı ortaya konmuştur. Düşen koni metodu kullanılarak elde edilen likit limitlerin büyük çoğunluğu çoğu ±%10 hata payı ile bulunabilirken, nodül yuvarlama metoduyla tayin edilen hemen hemen bütün plastik limitler ters ekstrüzyon yöntemiyle ± %10 hata payı ile bulunabilmiştir. Ters ekstrüzyon testi üzerinde yapılan rafinasyon çalışması, tek bir yöntem kullanılarak iki önemli kıvam limitinin kolay, etkin, ucuz ve hassas olarak belirlenebileceğini ortaya koymuştu