Numerical study on the rock muck transfer process of TBM cutterhead with clump strategy based on discrete element method

Abstract

This paper presents a numerical study on the rock muck transfer process of tunnel boring machines (TBMs) cutterhead. The discrete element method (DEM) is employed, and rock muck is modeled using a clump strategy that considers the geometric parameters of muck, such as gradation, shape and size. The numerical method is verified through tests conducted on a scaled cutterhead bend. The influences of the number and size of the mucking chute, muck shape, cutterhead diameter and revolutions per minute (RPM) on the ability and stability of muck transfer is investigated via numerical simulations. Results show that the muck transfer ability increases with the number, length, width, and area of the mucking chutes, but decreases with the cutterhead RPM. The muck transfer ability is strongly influenced by the muck shape, and the muck sphericity or the scrolling ability is a critical factor influencing the mucking performance of TBM cutterheads. The muck transfer stability improves significantly with the number of the mucking chutes, but no evident effect with respect to chute size. These findings may be useful to understand the muck transfer mechanism of TBMs and can be used as guidance for mucking chute design and TBM operation.