Ground Response to Pipe-Roof Tunneling of a Large Underpass in Shanghai Soft Soil

Abstract

Pipe roof method is an effective way for urban underpassing scheme. Due to the successive jacking of multiple pipes, the characteristics of ground response are distinctly different from single pipe or twin pipes. In this paper, the gradual ground loss by successive pipe-jacking and the causes of settlement are analyzed. The conclusions drawn from this paper show that: (1) The maximum incremental was right above the pipe axis which could be controlled within 1mm. (2) The shield effect of the former pipe on the latter one resulted in a 50% reduction of maximum incremental settlement. (3) The distribution of cumulative settlement curve was reflected by superimposed effect of staged ground settlements. (4) The results of settlement monitoring illustrated that the field measured settlements were basically tally with those of the simulated values, the goodness of fit was more than 85%.

Large rectangular cross-section tunnel undercrossing urban road by micro pipe jacking and joint assembly structure (MPJ & JAS) method in soft soils

“…Especially, Japan has gradually developed and applied the pipe roof method, and invented some construction methods for passing through railways, such as the under railway road tunnelling (URT) method 2,3 , the prestressed concrete roof (PCR) method 4 , the high-speed element pull and jointed element structure (HEP & JES) method [5][6][7] , etc. Through the site instrumentation, experiment and theoretical analysis, it is found that pipe roof can reduce soil disturbance and ground settlement [8][9][10] . With the advantage of the settlement control of the pipe roof, the roof-box jacking (RBJ) method was formed by combining the pipe roof method and the box culvert jacking method 11,12 .…”