Study on the excavation stability of anti-slide piles in slopes containing spherical boulders

The stability of anti-slide pile excavation in steepened cutting slopes containing spherical boulders during highway expansion projects has significant engineering implications. This study investigates the influence of boulder belt distribution and the position of mega-boulders on slope displacement and safety factor, based on the Meizhou-Shantou Expressway expansion project using finite element numerical simulations. The results indicate that shallow boulder belts amplify the self weight effect due to excavation unloading, increasing slope displacement and concentrating deformation toward the fourth level slope surface, thereby elevating instability risks. Mega-boulder behind piles redirects plastic zones backward due to their inherent strength, while cross-pile boulder belts exhibit reduced bonding interactions with soil compared to rear-distributed boulders. This study reveals the synergistic interaction mechanisms between boulder distribution and construction techniques, providing theoretical support and engineering guidance for the optimal design and safe construction of slopes with spherical boulders.