PETER GROUND IMPROVEMENT INC. (PGII) is one of the pioneers of soil nailing and shotcreting in the
Philippines.
Soil nailing is a procedure by which steel reinforcement is installed on a soil mass to mobilize frictional
resistance along the soil nail interface. The shear and pullout resistance of the nail is mobilized to prevent slides or shear failures in the soil. The resistance strengthens and reinforces the soil mass.
The soil nails are “passive” reinforcements or inclusions. The term “passive” means that the soil nails are not pretensioned (as tiebacks or anchors) when they are installed. The nail rebars are forced into
tension as the ground deforms laterally in response to the loss of support caused by continued excavation or by insufficient shear strength in the supporting soil mass. The grouting of the nail increases the overall shear strength, limits the displacement during and after excavation by providing a bigger area for friction to build up. A structural facing (commonly shotcrete) connected to the nails is used when the slope angle exceeds a predetermined critical value or when environmental conditions would cause deterioration of the reinforced soil over its design life.