Artık Toprak Zeminlerin Zemin-Su Karakteristik Eğrilerinin Belirlenmesi

Abstract

Matric and total suction pressure are two key concepts used in unsaturated soil mechanics. The soil water characteristic curves which are used to determine many engineering features of residual soil are the main purpose of this thesis. For this purpose, the soil mechanic experiments were carried out by using three different residual soil samples which were taken from Solfasol district in Ankara. The laboratory studies were conducted in two different phases. The first phase covers soil mechanics experiments. The experiments carried out in this stage are subsequently sieve analysis, Atterberg limits test, standard Proctor tests and direct shear box tests. Following the experiments carried out on each three soil samples, the second phase was initiated to examine unsaturated soil mechanics concepts. In the second phase, filter paper experiments were conducted to determine saturation degree, matric and total suction pressure values of the samples of residual soil. The filter paper moisture content graphs which are suitable for the matric suction pressure of the soil were drawn and soil water characteristic curves were formed. Within the scope of the thesis, pressure plate extractor testing apparatus were designed to determine matric suction pressure of the soil samples in a different way. Soil water characteristic curves (SWCC) were drawn with the results obtained from the experiments which were carried out using new device. The result of this study revealed that smoother soil water characteristic curves can be obtained by implementing matric suction pressure at a frequent interval to samples on clay soil during pressure plate experiments. Examining the soil water characteristic curves obtained from both the pressure plate and filter paper tests, it has been observed that the curves slope upwards as the clay proportion in the samples increased. As a result of SWCC analysis obtained from filter paper tests, the highest matric suction pressure value (4.44 bar) was found in the residual soil sample which has %21 clay content. On the other hand, matric suction pressure was observed as 4,19 bar in the reddish-pink colored soil samples containing the lowest proportion of clay %2,7. Filter paper and pressure plate test data show that the matric suction pressure value has increased based on the increase in fine grain size while it decreased due to the increase in coarse grain size.