Bearing Capacity Analysis Based on Optimization of Single Layer Depth of Reinforcement Below Rectangular Footing

Abstract

This paper presents a study based on laboratory model tests conducted with rectangular footing on unreinforced and geosynthetics reinforced crusher dust. The test was conducted at loose (RD = 29%) and medium dense (RD = 64%) state of crusher dust taking the variation of single layer depth of geosynthetic placed below foundation to find the maximum ultimate bearing capacity. The single layer depth was varied at a depth of 0.2, 0.25, 0.3 and 0.35B for loose state of crusher dust and for medium dense state, it was varied with 0.3, 0.4 and 0.5B (where B is the width of the footing). Also geogrid along with geosynthetic (stagged one above another) was used below footing at the optimum depth to find their combined effect. It has been observed that the inclusion of reinforcement at various depths provided below footing gives higher ultimate bearing capacity compared to unreinforced condition at both relative density states. For loose state, the optimum single layer depth of geosynthetic was found out to be 0.3B and for medium dense state, it was found to be 0.4B. The percentage variation of ultimate bearing capacity of reinforced crusher dust with respect to unreinforced at loose state (0.3B) was 112.56% and for medium dense state (0.4B) was 71.15%. Increase in relative density along with addition of reinforcement layer to the crusher dust has great impact on the bearing capacity of footing. At both the reinforced and unreinforced conditions, higher density produced higher result than the loose dense state of the material. Combination of geosynthetic and geogrid used as a single layer below footing at optimum depth for RD 29% and RD 64% resulted in higher ultimate bearing capacity compared to the single reinforcement and the percentage variation with respect to unreinforced condition, it is found out to be 121.85% at RD 29% and 74.46% at RD 64%.