Search Results (3)

The TBM disc cutter cuts soft–hard composite strata during shield construction, and the cutter–rock cutting process generates high temperatures and severe wear. In this research, different strength types of rocks are taken as objects to analyse the interacting rock-breaking force and cutter motion model. The effects of rock properties on wear are investigated, and the cutter ring wear mechanism and damage types are discussed. Combined with the thermal stress theory of elastomer and the abrasive wear theory, a prediction model for cutter wear depth and wear mass is proposed. The results of the study show that the type of wear is dominated by abrasive wear, with the highest probability of uniform wear occurring in cutting hard rock. Hard rock is the most abrasive to the steel material of the cutter ring, and the percentage of abrasive wear decreases for cutting soft–hard composite strata. The amount of abrasive wear is negatively correlated with the hardness of the cutter ring. The rock damage patterns are different when cutting soft and hard rocks, and the wear areas are located at the bottom and sides of the cutter ring, respectively. Considering the thermal effect, the depth of wear for cutting hard rock has a power function relationship with the installation radius, which is closer to the actual value. The theoretical models are generally lower than the actual measured values. The wear prediction model is useful for determining the replacement interval of the cutter and improving the rock-breaking efficiency. Full article

Disc cutter wear has emerged as a critical concern impacting the efficiency and cost budgets of TBMs (tunnel boring machines). Through statistical analysis of field data on cutter wear in a TBM tunnel, this study explores the wear rules of different types of disc cutters in granite. Grey sensitivity analysis is employed to investigate the sensitivity between the cutter ring wear rate of face cutters and two types of cutter wear influence parameters. Subsequently, reasonable parameters are selected to develop a new cutter life prediction model for face cutters. The results show that, with increases in the installation radius, the accumulated wear extent shows a linearly increasing trend for both the center and the face cutter, while it first increases and then decreases for gauge cutters, and the accumulated replacement number shows a linear growth trend for face cutters. The accumulated wear extent of the average single cutter position of gauge cutters is about 3 times that of face cutters and 7 times that of center cutters; the number of replaced cutter rings of the average single cutter position for gauge cutters is about 3–4 times that for center cutters and face cutters; and the average utilization rate of gauge cutters is the highest (80.97%). The cutter ring wear rate of face cutters is the most sensitive to three intact rock parameters (uniaxial compressive strength (UCS), Cerchar abrasion index (CAI), and equivalent quartz content (EQC)) and two TBM tunnelling parameters (cutterhead thrust (F) and cutterhead rotational speed (RPM)). Finally, a new cutter life prediction model (R² = 0.964) for face cutters is developed based on F, UCS, and RPM. The research results can provide a certain theoretical basis for cutter wear and cutter life prediction for the face cutters of TBM projects in similar geological conditions and TBM specifications. Full article

Accurate evaluation of cutter life at different cutter positions on the cutter head is helpful to determine the time of cutter change and reduce the time of cutter wear measurement, which is of great significance to improve the tunneling efficiency of tunnel boring machine (TBM) projects. Unfortunately, there is no unified cutter life evaluation index now. The field data of cutter wear are collected from a section of a long TBM tunneling water conveyance tunnel in China. Two kinds of cutter life evaluation indexes (based on the radial wear extent of cutter rings and replacement number of cutter rings) are selected and the variation rule between these two kinds of indexes with cutter installation radius is statistically analyzed. The results show that the regression relationships between the two kinds of cutter life evaluation indexes and installation radius mainly present linear functions and quadratic functions. Those regression relationships are affected by factors such as wear type, installation angle, cutter spacing, influence width, and allowable limit wear extent of cutter rings. Considering the calculation accuracy of the evaluation index, the actual working conditions of the disc cutter, and ignoring the influence of tunnel diameter, it is recommended to preferentially choose the radial wear extent of cutter rings per unit rolling distance as the evaluation index of cutter life. The research results can provide a reference for the selection of cutter life evaluation index, prediction of disc cutter life at different cutter positions, and establishment of cutter life prediction mode. Full article