Placement Depth and Layering Effect of Geogrid Reinforcement in Soft Subgrade Using Digital Static Cone Penetration Lab Test

The reinforcement using single-layer geogrid on a soft subgrade is an effective way of solving practical problems. However, unpaved roads are often subjected to high vehicular loads, which compromise the pavement’s strength, safety, and durability. The loading has to be restricted on these reinforced subgrades. With the use of multi-layered reinforcement, this study aims to offer a superior alternative design for supporting heavy loads on geomaterial. The location of reinforcement plays a crucial role in the overall strength. The experimental investigations were conducted on poorly graded sand (SP). The effect of single-layer geogrid reinforcement placed at different depths of the subgrade was evaluated. Further, the bearing capacity of the soft subgrade was compared for single, double, and triple-layered geogrid reinforcement. A laboratory digital static cone penetration test (DSCPT) was performed to assess the load–displacement behaviour of unreinforced and reinforced subgrade. The result shows that reinforced subgrade achieved higher resistance compared to unreinforced systems. An optimum combination of placement depths of double-layered reinforcement is proposed.