Mechanical properties of the combined medium-diameter anti-slide piles and tunnels under landslide loads at different sliding zone angles

In this paper, a technique is proposed to use medium-diameter piles in combination to support existing tunnel systems. The study investigates the stress response of tunnel lining structures and anti-slide piles for different sliding zone angles ranging from 0° to 50°, and analyzes the deformation patterns of the tunnel system with combined medium-diameter piles support through laboratory experiments and numerical simulations. Based on the study, the following conclusions have been drawn: as the angle of the sliding zone increases, the deformation of the pile body and the tunnel lining structure gradually decreases, leading to a reduction in earth pressure and bending moment values. When the angle of the sliding zone is less than or equal to 30°, the impact of the landslide on the tunnel lining structure is significant. However, when the angle of the sliding zone is more than 30°, the influence of the landslide's horizontal thrust decreases substantially, while the proportion of the landslide’s vertical load on the arch foot increases gradually. Numerical simulation was conducted to analyze factors, such as pile spacing, pile type, and anchorage depth. The findings indicate that for sliding zone angles less than or equal to 30°, the primary concern is the impact of the landslide's horizontal thrust on the tunnel structure. On the other hand, for angles greater than 30°, the focus shifts to the effects of the vertical load induced by the landslide body on the tunnel lining structure.