Engineering Geology

Engineering Geology

Analysis of slope instability mechanism due to unusual rainfall: a case study of talubin village landslides (north of Meyami)

Authors
Tahereh Daniyalnezad
Aliakbar Momeni
Shahrood University of Technology
10.22034/JEG.2025.19.3.104488
Abstract
Following an unusual period of rainfall period at the end of the previous winter, several landslides occurred in Tolubin village in early spring 2019. These landslides resulted in the destruction of 12 houses as well as causingdamage to roads and gas transmission lines. This this research was therefore conducted to investigate the mechanism of these landslides. The study was comprised four main phases: a literature review, field investigations, laboratory studies, and a slope stability assessment using Slide 6.20 software. During the field surveys, landslide-prone profiles were identified, and both disturbed and undisturbed samples were collected. The disturbed samples were used for laboratory tests, including determining the grain size distribution, calculating the Atterberg limits, performing calcimetry, conducting X-ray diffraction (XRD) analysis, and carrying out scanning electron microscopy (SEM) analysis. Additionally, 27 undisturbed samples were prepared for direct shear tests under varying moisture conditions. Finally, stability analyses of the studied profiles were performed in Slide software under different moisture conditions, considering both static and quasi-static states, based on the geometric characteristics of the slopes and shear strength parameters (internal friction angle and cohesion).. The obtained safety factors indicated that all slopes were on the threshold of failure under saturated static conditions and would certainly fail under saturated quasi-static conditions. In conclusion, the high sensitivity of the slope’s marly materials to moisture variations and the unusual rainfall in February and March 2019 were identified as the primary factors contributing to these landslides.
Keywords
Landslide
Tolubin
Marl
safety factor
slope stability quasi-static
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