Influence of abrasive waterjet pre-cutting slit on the performance of shield cutter cutting reinforced concrete

Abstract

To improve the efficiency and safety of shield machines cutting reinforced concrete (RC) obstacles, using an abrasive waterjet (AWJ)-assisted shield cutter to cut RC is considered a feasible solution. To explore the effect of an AWJ on a shell cutter cutting RC, laboratory experiments and numerical simulation methods were used to compare the breaking performance and damage mechanism of a shell cutter cutting RC with and without a slit. The results showed that the waterjet pre-cutting slit could effectively reduce the cutter force of the shell cutter and promote the cutting of steel bars. The reduction rate of the cutter force by the waterjet slit increased and then decreased with an increase in the penetration degree. When the penetration degree was 1.5 mm, the waterjet cutting slit had the best reduction effect on the cutting force. An optimal critical value was found for the waterjet cutting slit of the steel bar; when the waterjet slit was larger than ½ of the diameter of the steel bar, the steel bar was prone to tensile fracture under the cutting action. The waterjet pre-cutting slit reduced the residual cross-sectional area and stress distribution of the steel bar, which promoted the bending and tensile fracture of the steel bar and thus improved the cutting efficiency. Furthermore, construction recommendations for the AWJ-assisted shield cutting of RC obstacles were identified. The findings presented in this paper can provide useful reference information for the design and construction of AWJ shield machines.