Stability Analysis of a Landslide: A View with Implications of Microstructural Soil Characters

Abstract

The 2015 Devrek landslide is one of the largest and most puzzling features on the Devrek-Eregli Highway in Zonguldak Province, in the north-west of Turkey. The landslide which was activated in March, was about 700 m long, 110 m wide with a volume of 1,100,000 m3. In order to assess the landslide hazard in a systematic way, we have employed several techniques such as geotechnical, microstructural and finite elements (FE) modelling. X-ray diffraction and X-ray fluorescence studies show low clay content in the crown section and the amounts of illite and sepiolite do not exceed 25% where there is detrital sand indicating that there is continuous sliding activity. The main sliding body demonstrates implications of liquefaction according to the amount of fine sand and clay obtained by laboratory measurements. The most active clay group prevailing the landslide formation are illite and sepiolite. Furthermore, rounded fine quarts have increased sliding and rolling activity risk according to their physical structures combined with high-seasonal rainfall rate. The FE method was used for both static and dynamic slope stability investigations. Since the landslide region are in a very active tectonic region, earthquake-triggered landsliding strongly correlates with measured peak ground acceleration. Therefore, we have tested the model in numerical dynamic analysis, and the results show a deterioration in landslide stability during seismic loading which puts the study area at risk. All analysis carried out for the landslide assessment shows a continued landslide hazard for the residential areas close to the landslide foot zone.