THE SLOPE STABILITY OF SAND SLOPE WITH TWO ROWS PILE REINFORCING

Population growth in Indonesia affects the rate of urbanization as the increased construction development decreases the available land. The issue of limited land encourages people to make settlements or buildings near the slope edge. Various mitigation methods can be applied to prevent and avoid landslides and to overcome other problems that arise on the slopes, one of which is by strengthening the slopes. In this study, slope reinforcement was carried out by adding two rows of piles to increase slope safety. Firstly, we observed scaled slope models with or without pile reinforcing. Slope modeling was done with a test container of sand soil with a slope angle of 50° and using an aluminum pipe as a model for reinforcement piles. Pile diameter of the test model was varied on the second row (1.5 cm, 2.0 cm, 2.5 cm, and 3.2 cm). The bearing capacity of the scaled-model test results was used to estimate the increase in factor of safety (FoS) assisted by the finite element method (FEM) application in two-dimensional (2D) and three-dimensional (3D) FEM. According to the FEM test results, the FoS value of a reinforced slope with two rows of piles increased by 9.130% in 2D FEM and 34.296% in 3D FEM compared to an unreinforced slope modeling. The most significant FoS value was found in the second row of piles with the largest diameter of 3.2 cm. Additionally, the test results showed that the reinforced slope is susceptible to rotational slope failure.