Performance of Construction with New Pneumatic Caisson Method in Shanghai Soft Ground

Abstract

In the new pneumatic caisson method (NPC), soil excavation and removal is completed remotely by workers on the ground. In 2007, this method was successfully applied in a tunnel shaft in Shanghai. Combined with the construction example, field monitoring and measuring has been conducted. Typical monitored results, such as the working pressure, lateral earth pressure, reaction pressure, and ground movements, were presented and analyzed. In addition, a numerical approach considering the soil disturbance during construction was proposed to predict the soil movements induced by the NPC construction. It was successfully implemented in the three-dimensional finite element method (FEM) codes. Calculated soil movements were examined and verified by the field measurements. In the meantime, these results were compared with the ones obtained from the two-dimensional approach proposed by the authors in the previous study. Results showed that, they agreed well with each other, and in general the three-dimensional analysis results approached the actual situation more closely.