Abstract: To study the law of surface displacement during pipe roof construction of pipe-jacking group, this paper analyses surface displacement data based on the Tianlin Road passing under Middle Ring Road Tunnel Project in Shanghai. Measured data shows that deformation development during the pipe roof construction can be divided into seven stages: 4 construction stages and 3 suspending construction stages. The surface displacement during the pipe roof construction comprises ground loss settlement and ground heave caused by grouting. In the suspension stages, the surface displacement is consolidation settlement. In this paper, the surface displacement is described by the Peck equation. The width coefficient i of surface settlement trough and the ground loss ratio η were back analyzed from the field measured data. Based on the analysis results, the calculation formulas of i and η were proposed for Shanghai soft clay. i is related with the pipe radius R, pipe buried depth h and internal friction angle of soil φ, and the formula of η is described by a hyperbolic function of time after jacking. The surface heave caused by the grouting can be separated to the negative ground loss caused by each pipe jacking with grouting. The above method was used to predict the surface displacement and the predicted results were compared with measured data to verify the correctness of the method in this paper, which can provide scientific reference for the prediction of surface displacement caused by similar pipe roof method construction.  

Key words: pipe roof method, pipe-Jacking group, surface displacement, grouting heave, Peck equation