DONMA-ÇÖZÜLMENİN ETKİN OLDUĞU YÜKSEK RAKIMLI BÖLGELERDE SOLİFLÜKSİYON TÜRÜ TOPRAK AKMALARININ İNCELENMESİ

Abstract

In the last years, the eastern parts of Turkey have begun to receive more snowfall in the winter and the number of days under 00C has increased. As a natural consequence of this, soil frost depth is increasing every year. Especially in Erzurum, Erciyes and Artvin, the depth of frost penetration reached and passed about 1.5 meters. In plains where the groundwater level is close to the earth, frost effect can reach deeper parts of the soil. As a result of this, significant damage can occurs in the settlements built on the plains, particularly in superstructures with shallow grounds (roads, railways, airports, etc.) and in lower structures (sewerage, water network etc.). Frozen soil in the winter, starts melting at the spring then physico-mechanical properties of soil changes because of freeze-thaw effect. At the top side of the soil, there is a volumetric increase with frost and the soil acquires a porous structure. The effective stress falls due to oversaturated soil which is result of melting frozen water in the pores of the soil, the soil loses too much strength and landslides can be seen with the movement that is close to liquid behavior In the scope of the thesis study, soil flows in slopes which are reaching to extreme saturation after the melting of frozen soils at high altitude areas have been investigated in two separate titles which are field studies and laboratory studies. In field studies; The soil flows which can be seen at high altitude area such as nearest to Erzurum, Erciyes, Ilgaz and Artvin were investigated in field conditions. Also, with the Photographs which were taken by unmanned aerial vehicle (drone), photoscan and surfer softwares were used to create orthophotos and digital elevation models of the study areas. In this view, observed instabilities (soil flows, creeps etc.) in the field conditions were modelled and schematic information about the mechanisms of the soil flows were able to obtained. Index and mechanical properties were determined by experiments on soil samples taken from study areas. Also, a new device was designed for modelling soil movements which are results of freezing-thawing effect in the laboratory environment. The specially prepared specimens were subjected to experiments at different slope values in the new developed device, and the potential soil slides were constantly monitored. The photographs of specimens were taken before and after the soil slide experiment. Then, orthophotos of test sample and digital elevation models of test sample were created with using Photoscan and Surfer softwares. As a result of the created numerical elevation models and the experiments on the samples which are taken from the field, the mechanisms of soil slides which can be seen at low slope conditions and results of freezing-thaw effect were investigated. Also, ArcGIS software was used to interpret the ground movements depending on grain size.