The Influence of Soil Reinforcement on the Performance of Single Pile and Pile Group Under Pullout Loads

The influence of soil reinforcement on the uplift performance of single pile and pile group embedded in reinforced and non-reinforced is investigated for cohesionless soil with 60% relative density (Dr). Single pile and pile group models were conducted utilizing steel circular pile with bulges surface conditions. The pile group model was (2x1) piles with spacing of three times the single pile diameter (D). Several configurations of soil reinforcement were compared by varying the reinforcement type, the embedded depth, the width, and the number of reinforcement layers. Specifically, two types of reinforcement (SS30) and (TX150) were utilized in the laboratory experiments. The test results exhibit that the pullout resistance of the single pile and the pile group increase with the increase of the reinforcement layer width. For the single pile, the pullout resistance increases with the increase of the reinforcement width up to width of nine times the pile diameter. While for the pile group, the pullout resistance increases with the increase of the reinforcement width up to (nine + three) times the pile diameter, three times the pile diameter is the spacing between piles. In addition, for both single pile and pile group, inclusion of a double layer of geogrid with spacing between geogrid layers equal to twice the pile diameter will improve the pile capacity ratio more than in the case of the single layer of geogrid. However, the pile group efficiency using a single layer of geogrid is better than the group efficiency using a double layer of geogrid.