In the bustling city of Nanchang, where the metro system is expanding rapidly, a significant challenge has emerged: predicting and managing land subsidence caused by shield tunneling in water-bearing sandy soil layers. Traditional methods, such as the Peck formula, have shown considerable deviations due to unique local geological conditions. However, a recent study led by ZHOU Chenghua from Nanchang Rail Transit Group Co., Ltd., published in ‘Chengshi guidao jiaotong yanjiu’ (translated as ‘Urban Rail Transit Research’), offers a promising solution.
The study focuses on the interval of Nanchang Metro Line 3, where the existing Peck formula fails to accurately predict land subsidence. “The deviations were significant,” explains ZHOU Chenghua. “We needed a more precise tool to ensure the safety and efficiency of our tunneling projects.” The research team collected field-measured data and considered three primary factors affecting land subsidence: tunnel burial depth, tunnel radius, and the internal friction angle of the overlying soil.
By introducing a correction coefficient for maximum subsidence and performing linear regression modification of the Peck formula, the team derived a new calculation formula tailored to Nanchang’s conditions. The results were impressive. “The land subsidence curves predicted by the modified Peck formula closely matched the measured subsidence curves,” ZHOU Chenghua states. This accuracy is crucial for predicting and mitigating the risks associated with land subsidence during shield tunneling.
The implications of this research extend beyond Nanchang. Urban rail transit systems worldwide face similar challenges in water-bearing sandy soil layers. The modified Peck formula could provide a more reliable tool for predicting land subsidence, ensuring the safety and efficiency of tunneling projects. This is particularly relevant for the energy sector, where underground infrastructure often intersects with energy pipelines and facilities.
As cities continue to expand and metro systems grow, the need for accurate subsidence prediction becomes ever more critical. ZHOU Chenghua’s research offers a significant step forward, providing a tool that could shape future developments in urban rail transit and beyond. The study, published in ‘Urban Rail Transit Research’, serves as a testament to the power of localized research and its potential to drive global advancements.