Abstract

In this paper, a series of parametric three-dimension numerical simulations were carried out to estimate the face stability and to calculate the minimum allowable slurry pressure of pipe jacking tunnel in frozen ground for the first time. In total, 5120 of simulation schemes were done with different ground temperature, diameter and cover thickness of tunnel, cohesion and friction angle of frozen soil. In order to figure out the optimal grouting pressure, 4 groups of additional simulations are computed with the uniform face support pressure of 0.5, 1.0, 1.5 and 2.0 times of horizontal stress, σ_H, at tunnel axis. The qualitative analysis of heading face deformation mechanism and quantitative analysis between deformation profiles and influential factors were implemented to comprehend the heading face deformation characteristics when conducting pipe jacking tunnel in frozen ground. The results show that ground temperature plays a dominant role to control the face deformation of jacking tunnel in frozen ground. And, factors of tunnel diameter and cover thickness have relatively greater influence on the deformation regulation than that of shearing parameters of frozen soil, cohesion and friction angle. Finally, the minimum allowable slurry pressure for each simulation schemes are obtained, which may be used in construction the pipe jacking tunnel in frozen ground.

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