Similarity analysis and verification of slurry fracturing on shield tunnel face using centrifuge modeling

The geotechnical centrifuge test can restore the real stress field in the small-scale model, and provides an effective research method for investigating the slurry fracturing phenomenon of the shield tunnel face. There are several factors involved in the shield slurry fracturing, including the interaction between soil, slurry and tunnel, especially the existence of various fluids makes the dimensional analysis, test parameter scaling and data interpretation more complicated in the model tests. How to determine a reasonable similarity ratio is the key prerequisite for the success of the centrifuge modelling. On the basis of elucidating the basic physical process of slurry fracturing of shield tunnel face, a model test similarity analysis method based on dimensionless numbers is proposed. The similarity test design system of "tunnel-soil-slurry" based on the Butterfield dimensional analysis method is established to apply to geotechnical centrifuges for simulating the shield slurry fracturing. This system guarantees the similarity between the model system and the prototype system in terms of size, material, dimensionless number, time, etc., so that the real physical process of shield slurry fracturing can be accurately restored. Finally, the proposed similarity criterion is further verified by carrying out the slurry fracturing centrifuge modelling of the shield excavation face. The research results are of certain reference significance for the similarity analysis of the physical simulation of slurry fracturing.