Research on the Design Method for Uniform Wear of Shield Cutters in Sand–Pebble Strata

In order to solve the problem of uneven wear of the whole shield cutter caused by the different cutting trajectory length in the EPB shield tunneling process in sand–pebble strata. Based on the principle of friction and wear, the calculation method of cutter wear is established, and the theory of uniform wear of shield cutter and the design method of cutterhead and cutters are proposed. The EDEM particle flow numerical software was used to construct a uniform wear shield tunneling model of 6.6m in sand–pebble strata, and the uniform wear performance of the whole cutter was verified. The results show that: 1) The uniform wear of the whole cutters can be achieved by designing different cutterhead alignments and arranging a specific number of cutters on each trajectory radius; 2) The cutterhead alignment and the number of cutters are related to the “circumferential knife index β” and “formation lithology index n”. In a specific strata, the β value is the key factor affecting the design of the cutterhead cutter of the uniform wear shield, and the reasonable β value range is 1.83~2 for the conventional shield (2.5m≤R<6m). For large shield (R≥6m), a flat cutterhead should be designed, and r^2 cutters should be arranged on each trajectory; 3) Under the uniform wear scheme, the difference in the wear degree of the whole cutters is small, the tool wear coefficient of the outer ring of the cutterhead is greatly reduced, and the maximum continuous excavation distance without changing the cutters has significantly increased.