İsa Vural

Effects of Freezing and Thawing Cycles on the Engineering Properties of Soils

In this study, particular engineering characteristics of soil exposed to freezing and thawing cycles were investigated. Low plasticity clay (CL) soil samples (classified according to the USCS soil classification system) were sampled in situ, and some basic properties of these soil samples were investigated by performing sieve analyses, hydrometer tests, specific gravity tests, and liquid, plastic, and shrinkage limits tests. The same tests were also conducted after freezing and thawing cycles. Additionally, scanning electron microscope (SEM) tests to determine the microstructures of the soil samples and energy dispersive X-ray-EDX tests to determine the chemical compositions of the samples were performed. Finally, triaxial compression tests were conducted before and after the freezing and thawing cycles to determine the strength parameters of the soil samples. The experimental results show that the physical and mechanical properties of the soil changed significantly after the freezing and thawing cycles.

Investigation of the soil amplification factor in the Adapazari region

Turkey is located on the highly active Eurasian plate. A very active strike slip fault, the North Anatolian Fault Zone (NAFZ), crosses Turkey from east to west; earthquakes occurred on this fault on August 17, 1999 (Kocaeli) and November 12, 1999 (Düzce). Regional geology and subsoil conditions can significantly change the characteristics of ground motion. For this reason, determining soil amplification during an earthquake, especially for soft soils, is a very important topic for researchers. In this study, one dimensional ground response analyses were performed for selected Adapazari sites using the August 17, 1999 Kocaeli earthquake strong ground motion record with SHAKE2000 software. Soil characteristics and depth to engineering bedrock at the selected sites are different and the observed level of structural damage at these sites during the Kocaeli earthquake was also different. Calculated soil surface response spectrums at these sites were compared with the recommended design spectra of the Turkish Earthquake Code and the Eurocode 8. According to one dimensional ground response analyses, the calculated response spectra of the selected sites exceed the recommended design spectra of the Turkish Earthquake Code and the Eurocode 8. Calculations show that higher amplification ratios occur at higher periods due to soil behaviour. Results of this study indicate that local geological conditions may amplify ground motion at some periods and, due to this amplification, the calculated response spectra may exceed the recommended design spectra. Therefore, it is clear that local site conditions must be considered for earthquake-resistant engineering designs on soft alluvial soil deposits.

Effects of Freezing and Thawing on the Consolidation Settlement of Soils

The effects of freezing and thawing on consolidation parameters and other properties of soil were investigated experimentally. Samples of soils were collected in-situ and characterized in the laboratory. Index properties of soil samples were determined by conducting sieve analyses, hydrometer tests, specific gravity tests, and liquid limit, plastic limit, and shrinkage limit tests before and after 30 freezing-thawing cycles. Microstructure and elemental composition of the soil samples were determined by scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analysis, respectively. To determine the effects of freezing thawing onto the consolidation parameters of soil, consolidation tests were conducted on the samples before and after the freezing-thawing cycles. After 30 freezing-thawing cycles, consolidation settlements increased by about 23%.