Construction Techniques and Theoretical Researches of Modern Pneumatic Caisson

A ventilation shaft of internal metro tunnel in complicated geological conditions was constructed by unmanned remote controllable pneumatic caisson. Axisymmetric finite element model and large deformation analysis were employed to simulate its construction. The optimum excavation scheme was obtained by comparing caisson stable state and soil plastic zone distribution in various construction stages. In-situ monitoring was also adopted to analyze the influence of its construction on ground lateral displacement and surface settlement. Results show that all changes of surrounding environment were controlled in the allowable range. The key construction techniques in this successful project would be beneficial reference for similar projects in the future.