Earth Pressure Balance (EPB) shield machines have been widely used in subway construction due to their versatility and safety. During the shield tunneling process, the earth pressure in the shield machine chamber is crucial for controlling ground settlement and ensuring the safety of surrounding buildings. However, current research on the temporal and spatial evolution of earth pressure in water-rich sand layers and its relationship with ground settlement is relatively insufficient. This study focuses on the shield tunneling project between Liuzhou East Road and Puzhou Road on Nanjing Metro Line 11. First, laboratory and on-site tests were conducted to optimize the slump properties of the sediment. Then, based on Terzaghi’s theory and statistical methods, the temporal and spatial evolution trends of the earth pressure in the shield chamber under water-rich sand conditions were explored. Finally, by adjusting earth pressure control parameters on-site and monitoring ground settlement, the impact of earth pressure changes on ground settlement was analyzed. Results showed a linear correlation between the actual earth pressure and shield burial depth. For water-rich sand with medium permeability, the theoretical earth pressure was calculated using Terzaghi’s water-soil combined method in shallow sections, and the average of combined and separated methods in deep sections. The decay envelope showed an exponential downward trend, with rapid decay initially and slower decay later. As earth pressure control values increased, pre-consolidation settlement increased, instantaneous settlement decreased, pre-consolidation settlement rate slightly increased, and instantaneous settlement rate decreased. When excavation pressure was below theoretical pressure, higher instantaneous settlement rates could threaten surface structures. This research offers vital theoretical and data references for shield tunneling in water-rich sand layers and supports related EPB shield machine theory studies.
Ren et al. (Tue,) studied this question.