2025/01/01 by Mukhtiar Ali Soomro
Engineering · #Geotechnical Engineering and Analysis #Geotechnical Engineering and Underground Structures #Geotechnical Engineering and Soil Stabilization
paper · doi:10.1139/cgj-2024-0199
This research utilized three-dimensional centrifuge model experiments and back-analyses with a hypoplastic model to assess the performance of a laterally loaded 2 × 2 pile group subjected to twin stacked tunnelling at different depths. The first tunnel was excavated near the pile shaft ( C/ D = 1.5), and the second tunnel was placed either near the pile toe, below the pile group, or directly underneath it in tests CD1.52.7, CD1.53.7B, and CD1.53.7U, respectively. A parametric study was also conducted to examine the effects of various factors on the pile group responses, including the tunnelling sequence, lateral load direction, tunnel volume loss, and the tunnel depth and location. The results revealed that the most significant lateral movement occurred in test CD1.53.7U, while the highest tilting (0.98%) was observed in test CD1.53.7B. The first tunnel induced “dragload” due to negative skin friction. Excavating the deeper tunnel before the shallower one significantly reduced cumulative lateral pile cap movements and tilting. The direction of lateral load significantly affected lateral movement and bending moment distribution along the pile. Additionally, the depth and location of the tunnel relative to the pile group were crucial in determining the induced lateral displacement and bending moment at the pile head.