Plate load tests for investigation of the load–settlement behaviour of shallow foundation on bitumen-coated geogrid reinforced soil bed

The paucity of the desirable construction land in India due to day by day increasing population has put grand challenges in front of engineers. So they accentuated the use of undesirable construction land which is having low bearing capacity and large plastic deformation. Among several ground improvement techniques, geosynthetic reinforced soil system is widely adopted as foundation medium keeping in view its economical benefits and sustainable development. Therefore, the main objective of this study was to investigate the effect of a bitumen-coated geogrid reinforcement on the bearing capacity ratio of a shallow foundation in a two-layer silty clay foundation bed. The top layer of locally available silty clay was compacted at OMC (19%) with 0.95MDD, and the bottom soft layer was compacted at dry side of OMC (15%) with 0.75MDD. Various model plate load tests were carried out using a square footing of size 200 mm and thickness 25 mm over a silty clay bed reinforced with bitumen-coated geogrid BX-40, BX-60 and BX-80 having different ultimate strengths in a test tank of dimensions 1000 × 1000 × 1000 mm. The effect on bearing capacity and plastic deformation due to varying end conditions of geogrid reinforcement was also investigated. The other various parameters investigated were the top spacing ratio, width of the geogrid, no. of layers of the geogrid and the stress distribution in various reinforcement layouts. The bearing capacity ratio of reinforced clay was found to be increased by 20–55% than unreinforced clay. The settlement reduction factor of reinforced clay was increased by 9–40% than unreinforced clay. Also the vertical stresses were reduced up to 20% in reinforced clay.