Wear characteristics of shield cutters in sand-pebble strata based on EDEM

In order to reveal the wear characteristics of typical EPB shield cutters in sand–pebble strata and guide the design and layout of shield cutters in the strata, the particle-cutter wear contact parameters are calibrated through the indoor triaxial tests and discrete element software simulation analysis of EDEM. An EDEM numerical shield model for the sand–pebble strata is established based on the Beijing New Airport Line section from Cigezhuang station to No.1 air shaft in the sand–pebble strata. The wear characteristics of typical rippers and scrapers during soil pressure balance shield tunneling in the sand–pebble strata are visualized, and the model is verified through an actual project. The research results show that: (1) The rippers for plowing loosely the undisturbed soils are the essential cutting tools with an excessive wear, and the manifestation is continuous friction and wear on the alloy surface of the cutting head and at the blade edge. (2) The scraper for the purpose of stripping and discharging is mainly characterized by random pitting wear on the soil surface of the blade body and the alloy surface of the blade head, and the wear amount is small. (3) The wear amount of the radial cutter of the cutterhead increases with the increase of the radius of the trajectory and the height of the cutter body. The wear coefficient of the high cutter is higher than that of the low cutter on the same trajectory, and the high cutter has a protective effect on the wear of the low cutter. The gradient arrangement of cutters can extend the single continuous excavation distance and improve the efficiency of shield tunneling in the sand-pebble strata.