Temporal and spatial distribution of the grout pressure and its effects on lining segments during synchronous grouting in shield tunnelling

Abstract

The advance of tunnel shield creates void between the lining segments and the surrounding rock at the tail part of the tunnel shield. Grout is continuously injected into that void, to control the ground subsidence and maintain the segments stability. The grouting process must be precisely controlled and monitored to prevent any undesired significant subsidence or segment damage. In this work, a novel model to characterise the temporal and spatial distribution of the grout pressure in the rock-segment void is proposed, based on the theory of group diffusion and consolidation. The temporal variation of the grout viscosity is also considered in the proposed model. The proposed model is verified against field monitored data of the grout pressure, and exhibits quite good performance. Then a three-dimensional finite element model of the lining segments is developed to study the effects of the grout pressure on the mechanical response of the lining segments. The mechanical responses of the lining segments, in terms of internal force, moment and stress profile, are thoroughly analysed. These mechanical responses are also verified against the field monitored data, to further validate the proposed model of grout pressure distribution.

Keywords:

• Shield tunnel
• synchronous grouting
• grout pressure distribution
• varying grout viscosity
• mechanical response of lining segments