Slurry Support Mechanism for Shield Tunneling Considering Slurry Infiltration and Cutter-Disk Cutting Effect

Abstract

This study aims to clarify the mechanism of slurry support and its effect at different stages of slurry infiltration in shield construction. The analysis of various expressions of slurry support throughout the entire excavation cycle is based on the theories of slurry infiltration effects and the cutting action of the cutters. Furthermore, the limit support pressure calculation method at the tunnel face is modified considering the slurry support mechanism observed during different slurry infiltration stages. Some of the main conclusions drawn are as follows. (1) When slurry deep infiltration occurs, the main form of slurry support is the seepage force acting on the soil skeleton. At this stage, the limit support pressure from the filter cake model will not be sufficient to meet the tunnel face stability requirements. (2) The effectiveness of slurry support is influenced by both the slurry infiltration state and the cutting action of the cutterhead. Slurry infiltration and shield tunneling together create a quasi-static equilibrium state, in which slurry support is effective only when the infiltration velocity corresponding to this state is greater than the critical velocity. (3) And the influence of shield tunneling parameters on the slurry support mechanism is significant. Compared with the cutter’s penetration degree, the cutter’s rotational speed has a more pronounced effect on the conversion rate of slurry support pressure at the shield tunnel face.