Influence of Intensity and Position of Surcharge on the Performance of Soil Nail System: Fid-Bau Portal

Influence of Intensity and Position of Surcharge on the Performance of Soil Nail System

Krupa, H. R. / Prasad, S. K.

Soil nailing is one of the efficient and economical methods of reinforcing soil and deep excavation. The complex and composite interaction between the soil, the nail and the facing determines the performance of the soil nail system. However, while analyzing and designing the soil nail wall, the surcharge load is rarely considered and even when considered, its position and intensity are not well defined. Hence, the question is, can a surcharge be added on top of soil nail excavation? If so, what is the right choice of position, magnitude and width of surcharge? In this paper, efforts are made to consider the magnitude of surcharge and its location on top of the soil nail wall excavation and to study their effect on the overall performance of the system. Numerical simulations are carried out using PLAXIS, in which loaded strip footings are placed on top of the wall at various positions. The soil nail wall is constructed stage-wise with the footing placed on top. It is observed that the system experienced severe conditions with increased stresses and increased displacements when the footing was placed at the edge (face of the wall) compared to other cases where the footing was placed away from the wall face. From the present study, it was inferred that the surcharge load, if applied on top of soil wall must at least be at a distance equal to the wall height, from the wall edge and the intensity of surcharge load shall be as low as possible. The footing or the surcharge at any case shall not be placed where the nail line ends. Therefore, it is further emphasized that intensity and position of footing are the functions of soil properties (bearing capacity), load dispersion, nail geometry, density, and the wall height.