Numerical study of the effect of confining stress on rock fragmentation by TBM cutters

Analysis of Roadheader for Breaking Rock Containing Holes under Confining Pressures

“…The rock fragmentation process using the cutterhead is also a process of energy dissipation. Generally, during the advancement process of the cutterhead, the energy dissipation can be divided into several modes: elastic strain energy, plastic strain energy, brittle failure energy, ductile failure energy, thermal energy, and so on [11]. Specifically, two energy modes are mainly responsible for the rock fragmentation: the brittle failure energy consumed by tensile failure as well as the ductile failure energy consumed by shear and compressive failure.…”

“…This is consistent with the test results obtained by Ma el al. [10,11]. Numerical simulations on rock cutting with lateral pressure were performed by Huang et al [12] using the LS-DYNA software, with the results showing that the cutting force increases with an increase in the lateral pressure.…”

Rock Fragmentation Characteristics by TBM Cutting and Efficiency under Bi-Lateral Confinement

“…The results demonstrated that a small increase of confining pressure caused the position of the maximum tensile stress to move significantly from the vertical thrust line and increased the crack vertical angle. Cook et al [23], Liu et al [24], and Ma et al [25] reported that cracks tend to develop to the free surface once the confining pressure increases. It is worth mentioning that field investigations, laboratory tests, and numerical simulations can promote perceiving the mechanism of rock breaking of TBM in the presence of various confining pressures.…”

“…It is worth mentioning that field investigations, laboratory tests, and numerical simulations can promote perceiving the mechanism of rock breaking of TBM in the presence of various confining pressures. However, most previous studies were undertaken as two-dimensional (2D) [23][24][25], imposing barriers to truly representing the breaking mechanism in three-dimensional (3D) spaces.…”

“…Ma et al [25] studied the impact of different cutter spacings on the excavation's efficiency using a TBM cutter, in which a series of rock cutting tests were undertaken using five sets of cutter spacing. Balci [26] and Chang et al [27] used disc cutters to perform a dynamic linear cutting test and analyzed the rock failure mechanism based on different rock conditions, disc cutters' parameters, loading parameters, and rock failure parameters, which were collected during the cutting process.…”