In the bustling heart of Shanghai, where the city’s rapid expansion meets the intricate dance of high-speed rail infrastructure, a critical challenge emerges: how to excavate deep foundation pits without compromising the stability of nearby high-speed railway subgrades. This delicate balancing act has been the focus of groundbreaking research led by HE Shuqi, a distinguished researcher at the Shanghai Key Laboratory of Rail Infrastructure Durability and System Safety.
The study, published in ‘Chengshi guidao jiaotong yanjiu’ (translated to ‘Urban Rail Transit Research’), delves into the optimization of isolation pile parameters, a protective measure crucial for maintaining the integrity of rail transit foundations adjacent to high-speed railway subgrades. “Deep foundation pit construction can adversely affect the stability of existing subgrade structures,” explains HE Shuqi. “Isolation piles installed outside the foundation pit can effectively control the deformation of the surrounding environment caused by excavation.”
The research team conducted numerical simulations using finite element software, focusing on the construction of the No.1 ventilation shaft excavation for the Shanghai Suburban Railway Airport Link Line. They examined five key design parameters: isolation pile length, distance from the underground diaphragm wall, pile spacing, pile diameter, and pile stiffness. Through an orthogonal experimental design method, they constructed 18 working condition combinations to evaluate the control efficiency of isolation piles on horizontal displacement and settlement.
The findings reveal that isolation piles can effectively control the horizontal displacement of shallow subgrade pile foundations but may amplify the horizontal displacement of deep subgrade pile foundations. The distance between isolation piles and the underground diaphragm wall emerged as a critical factor influencing all evaluation indicators. “To ensure the safety of adjacent high-speed railway subgrades, it is recommended to appropriately increase the distance between isolation piles and the underground diaphragm wall,” advises HE Shuqi.
The commercial implications of this research are substantial, particularly for the energy sector, which often requires extensive underground infrastructure. By optimizing isolation pile parameters, construction projects can minimize disruptions to existing rail infrastructure, reducing downtime and associated costs. This research not only enhances the safety and efficiency of urban rail transit construction but also paves the way for more sustainable and resilient infrastructure development.
As cities continue to expand and infrastructure demands grow, the insights from this study will be invaluable for engineers and planners. The work of HE Shuqi and their team at the Shanghai Key Laboratory of Rail Infrastructure Durability and System Safety underscores the importance of innovative solutions in addressing the complex challenges of modern urban development. This research is a testament to the power of scientific inquiry in shaping the future of our built environment, ensuring that progress and safety go hand in hand.