Slope Stability Problem in the Chittagong City, Bangladesh

Md Shofiqul Islam; Md Ashraf Hussain; Younus Ahmed Khan; Mohammad Akterul Islam Chowdhury; Md Bashirul Haque

doi:10.37591/joge.v1i3.4036

Abstract

Chittagong, the major port city of Bangladesh is seriously and violently vulnerable for landslide from geological and geographical point of view for many specific reasons. Along with the steep slope, slope cutting, natural weathering and antecedent rainfall causes for landslide of the city during the rainy season caused by thunderclap of heavy storms. This paper presents a quantitative analysis of slope instability problem of the Chittagong city by technical and mathematical analysis of Geotechnical properties of the region from laboratory measurement and modeling the selected vulnerable slopes using a different slope stability technique for circular slicing methods. The soil samples collected from the selected locations which show that the soils are medium to very fine sand consisting of medium to fine grains ranging from 37 to 57% with a tiny amount of silt and clay instance ~7%. Very low cohesive strength was observed for loose and dry samples. Angles of internal friction from 13° to 40° were determined while slope angles from 50° to 80° or more are measured distinctly. This steepness of the slopes is caused for landslide evident from the mathematical modeling. Most of the slopes beyond the friction angle of the slope will fail if the soil will be loosened. Modeling results also show that water pressure builds up within the soil of the slopes were mainly responsible for failure from the natural setting. To protect the slope from failure, the adequate supports have to be suggested which could enable to save the lives and properties of the vulnerable area of the city. Keywords: Chittagong city, slope stability, sand, friction angle,cohesion