Abstract: This paper presents an investigation into anti-sliding characteristics of high-pressure grouting steel-tube micropiles under actual stress condition. Full-scale model experiments were performed on landslides reinforced with a single high-pressure grouting steel-tube micropile and a group of micropiles, and with a single gravity grouting micropile as a comparison experiment. The results demonstrate that the root-shaped bonded bodies near sliding zone are formed due to the splitting of soil around the micropile by the high-pressure grouting. High-pressure grouting is able to improve soil mechanical properties significantly in landslides, enhance the resistance deformation capability of the pile bodies, decrease the bending deformation of piles, and leads to an increase of 152.6% for shear strength of the soil in the sliding zone. Comparing with the gravity grouting micropile, the horizontal ultimate loads of the landslides reinforced by a single high-pressure grouting steel-tube micropile and a group of micropiles increase by 37.8% and 71.2%, respectively. In the high-pressure grouting group piles, the horizontal forces and bending moments acting on the backward pile are maximum, followed by the forward pile, while those acting on the middle pile are minimum under the condition of limit state. The failure locations of the piles are characterized by the maximum bending moment. The failure mode of the concrete around the piles transforms from crush failure located at trailing edge to tension failure at leading edge of the landslide.

Key words: landslide reinforcement, high-pressure grouting steel-tube micropile, anti-sliding characteristics, full-scale model experiment