Model test of cantilevered double-row anti-sliding piles in steeply slipping landslides

The mechanism governing pile–soil and rock interaction in steeply slipping landslides is quite different from that observed in gently slipping landslides. In particular, the mechanism responsible for the double-row anti-sliding pile stress is notoriously complex. Using the K285 landslide along the Neijiang-Liupanshui railway route as an example in our study, we demonstrated that pile safety in steeply slipping landslides was based on the similarity principle. A physical model interaction test between the double-row anti-sliding piles and the landslide was performed to determine the impact of factors such as the failure mode as well as pile stress, bending moment, and head (top) displacement on the safety of a project site. Herein, we noted that the landslide thrust located behind the lower row was about ½- to 1 times that of the upper row when the distance between two rows of anti-sliding piles was about the same as the pile length, assuming that the same loading conditions were used. Also, the resistance of the sliding mass in front of the upper row piles had a maximum value, and the maximum bending moment of the lower row was about 1 3 - to 1 times that of the upper row under the aforementioned assumptions. The results indicated that the anti-sliding pile heads should be 0.5–1.0 m higher than the ground surface around the piles and backfilled behind the piles. Additionally, the bedrock located before the piles adopted a “wedge” fracture with a depth corresponding to the position of the maximum bending moment. The associated fracture angle and depth were related to the friction angle of the bedrock and the inclination angle of the slipping surface. In conclusion, the study provided insight that will be useful for designing anti-sliding piles to mitigate the occurrence and impact of these types of landslides.