Unsaturated soil slope properties and shallow landslides development in Souk Ahras area, NE, Algeria

Abstract

Shallow landslides in Souk Ahras region, NE Algeria, occur usually after prolonged rainfall events. Three localities which are Zaarouria, Hammam Tassa, and Mechroha were chosen to study these landslides and the conditions of their occurrences. They have been observed to afect mainly agricultural lands, main supplies, and the road network. This paper aims to fnd the relationship between the rainfall, the soil engineering properties, the geology, and the geomorphology. A number of feld trips were organized to the study areas where landslide masses were described and mapped as well as some feld measurement such as natural moisture content and sampling. In the laboratory, we establish gain size distribution, Atterberg limits, density, and efective cohesion and internal friction. Then we established the unsaturated soil property functions such as the soil water characteristic curve (SWCC) and the hydraulic function. The stability computation was undertaken using, GeoStudio software 2020, a coupled analysis where the Seep/W simulates the seepage and the Slope/W for the safety factor. The results show that the sector study containing: silty sand (SM), well graded sand with silt and gravel (SW-SM), and clayey sand with Gravel (SC) while hydraulic conductivity varies between 4.5. 10−6 for 4.10−5 and 10−3 m/s. The factor of safety varies between 0.8, 1.16, and 0.8. In conclusion, our study confrms the feld observations as shallow landslides have been numerous in mars 2019 when rainfall reaches 110 mm. Moreover, high permeability soils, in Mechrouha, show a more dramatic decrease in the factor of safety as the 100=-mm rainfall amount is reached while it decreases gradually for the other two less permeable soils of Zaarouria and Hammam Tassa.

Access Article

Related Publications

Metrics