Lal Lawmsanga , Benjamin Roluahpuia, Lal Dinpuia, V. Vanthangliana, Jayanta Jivan Laskar, Vanlal Hriatsaka
The traits of residual soils are dependent upon the environmental factors of climate, parent materials, topography and drainage, and time. The structures and designs of buildings are greatly affected by the properties of soils; such as plasticity, compressibility, or strength. A proper foundation soil is needed for the stability of engineering structures like dams, buildings, bridges, tunnels, towers, etc. one that is built into or on top of the soil. Changsari is situated on the north bank of the Brahmaputra River, Kamrup district of Assam. Based on the geotechnical investigations, the region comprises four different soil horizons; i.e. Horizon A, Upper Horizon B, Lower Horizon B and Horizon C, classified as Clay (or organic soil) with low plasticity, Silt with high plasticity, Silt with low plasticity, and Clay with low plasticity respectively. The cohesive strength (C) decreases with depth, and the grain sizes vary in each horizon. The results of the geotechnical investigations show that the geotechnical characteristics of the residual soils discovered in the three separate research areas follow a consistent pattern.