Variability of cohesion and angle of friction as a function of water content in fine soils in the municipality of Lalo (Benin)

This article deals with the variability of the cohesion and friction angle of clay soils as a function of their water content. It focuses on the fine soils of Lalo in Benin. Clay soils swell or shrink depending on their moisture content, which can cause stability problems and cracks in buildings. Benin's median depression, where the soils studied are located, has clay formations that are prone to shrink-swell, leading to differential settlement and damage to buildings. The aim of the study is therefore to characterise these formations and understand the influence of water content on their shear strength, measured by cohesion and angle of friction. Soil samples have been taken from various sites and subjected to laboratory tests to determine their physical properties. The results show that the soils studied are fine, mainly clay, with a natural water content varying between 27.47 % and 42.92 %. When the water content varies by 10%, cohesion varies from 4 kPa to 25 kPa and the angle of friction varies from 12° to 27°. It can be seen that cohesion and the angle of friction increase with the decreasing of water content. The results of this study will be recorded in a database so that they can be taken into account in the design of structures