Abstract:

A method of advancing box-culvert with pipe roof was used in soft soil ground for the first time in a tunnel of Shanghai Middle Ring Road. The first step is to jack a steel pipe or a tube of some other material into soil between starting and accepting shafts. Waterproof material is then injected into the lock-join to form a close underground space. Construction of box culvert jacking is complicated, and easy to cause ground deformation. This paper studies characteristics of ground movement during construction of large section box-culvert jacking based on measured data. Some new laws of ground movement are found which is different from those of excavating methods. Three dimensional finite element method (FEM) model is established to simulate the process and ground movement of advancing box culvert. The model can simulate the state of excavating soil inside the pipe roof. Simulated data are compared with practical measurements, showing satisfactory results.

Key words: pipe roof method; box-culvert jacking; ground surface deformation; three-dimensional finite element simulation