Performance of Geosynthetics Reinforced Subgrade Subjected to Repeated Vehicle Loads: Experimental and Numerical Studies

Abstract

Use of the geosynthetics to strengthen the soil is one of the highly desirable techniques under static and dynamic loads. The present study describes the experimental and numerical studies performed on the geosynthetic reinforced subgrade subjected to repeated vehicle loads. The cyclic plate load tests were conducted on the sand subgrade reinforced with planar and 3D geosynthetic reinforcements. The vehicle load was simulated by applying a repeated load of magnitude 275 kPa with 1 Hz frequency on the reinforced subgrade. Results of the experimental investigations revealed that the performance of the subgrade soil improved significantly in the presence of reinforcements. The estimated parameters illustrated the three-fold reduction in settlement of the subgrade in the presence of reinforcement. Further, the heaving of the subgrade soil was found completely arrested with the use of geosynthetic reinforcement. The three-dimensional geocell reinforcement performed effectively as compared to planar geogrids under dynamic load. The measured pressure values at different depth demonstrated a significant reduction in the pressure in the presence of reinforcements. Besides, numerical simulations were performed using PLAXIS 2D to understand pressure and settlement distribution patterns in the reinforced subgrade. In overall, a good agreement was observed between numerical and experimental results.Abbreviations: B, width of geocell mattress (mm); C, cohesion of unreinforced sand (kPa); C c , coefficient of curvature (dimensionless); C r , increased apparent cohesion (kPa); C u , uniformity coefficient (dimensionless); C , total apparent cohesion (kPa); d 0 , equivalent geocell pocket diameter (mm); D, width of loading plate (mm); D 10 , effective particle size (mm); δ, soil surface settlement (mm); e min , minimum void ratio (dimensionless); e max , maximum void ratio (dimensionless); E, young's modulus of elasticity (kPa); ε a , axial strain (dimensionless); G, shear modulus (kPa); G s , specific gravity of sand (dimensionless); γ d , dry unit weight (kN/m 3 ); h, height of geocell (mm); H, height of sand bed (mm); k p , coefficient of passive earth pressure (dimensionless); M, secant modulus of geocell material (kPa); N r , number of loading cycles for reinforced case (dimensionless); N u , number of loading cycles for unreinforced case (dimensionless); r, radial distance from the center of loading plate (mm); S 0 , settlement of unreinforced subgrade (mm); S r , settlement of reinforced subgrade (mm); σ n , horizontal stress increment (kPa); σ ' yy , vertical effective stress (kPa); w, specific weight (kN/m/m); W, width of the sand bed (mm); µ, poisson's ratio (dimensionless); z, depth of geocell (mm); α/β, rayleigh damping parameters (dimensionless); φ, angle of internal friction (degrees); ψ, dilatancy angle (degrees).Frontiers in Built Environment | www.frontiersin.org 1 February 2020 | Volume 6 | Article 15

Performance evaluation of reinforced earth walls with sustainable backfills subjected to railway loading

“…Backfill soil is weak in tension and the reinforcement strips provide adequate tensile strength to the backfill soil, leading to improved RE wall performance. The reinforcements also increase the load carrying capacity of backfill and reduces the overall settlement (Hegde and Palsule, 2020). Figure 13 shows the tensile force in the topmost reinforcement at two different distances from the facing.…”