A novel three-dimensional mechanical model for rotary cutting in soil considering wear status and its experimental verification

Cutter is the main cutting tool for shield tunneling in soft soil, so the mechanism of cutter cutting soil is the basis of efficient shield tunneling. This paper proposes a model for revealing the cutting mechanics of shield cutter in soft soil considering the effect of wear. A new analytical method for calculating the cutter force, which can be used in soft soil, was established based on the theory of Rankine's passive earth pressure. The model is composed of three parts: a central failure zone and two side failure zones. To verify the proposed method, an indoor cutter wear test system was independently developed, and the test results show that the proposed model is more in line with the real cutting state compared with the Mckyes-Ali model. Parametric analysis indicates that the parameters associated with the cutter (width, front angle, blade angle, and cutting depth) have important influences on the cutter force and the cutting ability. The results also show that the cutter front angle and blade angle both have a significant impact on the cutter force and the cutting ability. In practical applications, it is essential to strike a balance between the decreased cutting ability of the cutters and the overall improvement in shield tunneling efficiency.