Investigation on Rock Disintegration and Clay Stabilization: A Case Study for the Landslide Prevention at Chattogram Hill Tracts of Bangladesh

A landslide is a natural disaster that often happens in high terrain such as the Chattogram Hill Tracts of Bangladesh. Besides damaging geology and soil properties, reckless deforestation is the result of certain farming practices, urbanization, greater population density and improper land usage, which has triggered frequent devastating landslides in this area. This study primarily determines the landslide-induced risk zones in this area with intensity and respective population density. Subsequently, a series of experimental investigations are conducted on the existing sedimentary rock (shale) with the mixing of the sodium carboxymethyl cellulose (CMC) chemical to understand the slake durability and crack changing pattern at different environmental conditions. The particle size of the collected shale samples from the Chattogram-Rangamati Highway was analyzed at the laboratory, and thus the elemental compositions were examined. The influence of CMC concentration at different temperatures was examined in terms of total dissolved solid, pH, and conductivity to determine the optimum concentration for minimizing shale disintegration and its stabilization. The test results demonstrated that the Chattogram-Rangamati Highway is composed of silt, clay, and fine sands with a trace of illite. Illite’s behavior is complex to some extent, particularly when it is dissolved in water; further, the mineral is primarily responsible for the formation of fissures in shales. This study revealed that doses of 4 and 6 g/L of CMC can successfully reduce the shale disintegration at 20°C and 40°C, respectively, when exposed to water. The findings of this research may contribute to provide insights into landslides in the identified zone or similar sites, thus ensuring a cost-effective solution and safety of the occupants.