Tunnel Boring Machine Disc Cutter Research Articles

Enhanced wear prediction of tunnel boring machine disc cutters for accurate remaining useful life estimation using a hybrid model

Enhanced wear prediction of tunnel boring machine disc cutters for accurate remaining useful life estimation using a hybrid model

Transfer component analysis-driven domain adaptation approach for estimating the life of tunnel boring machine disc cutters

Estimating the life of disc cutters in tunnel boring machines is crucial for tunnel excavation efficiency. Accordingly, generating accurate predictions of the state of disc cutters can prevent unexpected downtimes while optimizing cutting performance. The literature presents investigations of the application of machine learning (ML) for estimating the disc cutter life. Nevertheless, diverse excavation conditions and data scarcity have stimulated research on transfer learning (TL) frameworks that tailor models for different domains, that is, domain adaptation (DA), by generating a common subspace in which the discrepancies among them are minimized. This study presents an end-to-end framework to estimate the disc cutter life through transfer component analysis, a DA-based method for projecting different domains by considering excavation project datasets in a common space; then, different ML models are trained, including linear, probabilistic, and neural methods. The results revealed that the Gaussian process regression model was superior to other methods, with R2 = 0.99. In conclusion, TL is a valuable tool for estimating disc cutter life across different domains, enabling accurate predictions and leveraging knowledge to mitigate data scarcity challenges. In addition, an explainable AI analysis is conducted to quantify and identify relevant features impacting negatively on the disc cutter life, evidencing great contribution from the cutter rotation speed, quartz content, screw rate and specific energy.

Numerical investigation of temperature distribution on a tunnel boring machine disc cutter affected by geomechanically and excavation parameters

This study focuses on the thermal behavior of tunnel boring machines (TBMs) through an in-depth investigation into the temperature distribution of their disc cutters. Utilizing the differential quadrature method (DQM), the research conducts a comprehensive numerical analysis to assess the impact of excavation and geological parameters on disc cutter temperature and wear. The accuracy of the DQM model is validated against the finite difference method (FDM), demonstrating comparative results with reduced computational requirements. The findings indicate a significant correlation between disc cutter temperature and various factors, such as rotational speed, spacing, geological conditions, and material strength. Notably, increased spacing or cutter speed leads to higher temperatures and accelerated cutter wear. Moreover, geological factors, particularly rock strength, influence friction coefficients, affecting disc cutter temperatures significantly. For instance, even a slight increase in cutter spacing results in a substantial 65% rise in cutter consumption, underscoring the relevance of these findings for life cycle assessment (LCA) evaluations across diverse geological and environmental conditions in TBM operations.

Water saturation effects on rock abrasivity and TBM tunneling efficiency

Tunnel boring machine (TBM) tunneling efficiency is influenced by surrounding rocks, TBM design, and interaction between the TBM cutter and rocks. Using a case study from a water conveyance tunnel project located in northwestern China and involving five different lithologies (metamorphic andesite, sandstone, granite, quartz schist, and quartz diorite), this work investigates the water saturation effects on Cerchar abrasivity index (CAI) and its correlations with other physical and mechanical rock properties and TBM disc cutter and energy consumption. The results show that water saturation reduces CAI for all examined rocks except for the quartz diorite at the 90 % confidence level. CAI of saturated rocks (CAIsat) has statistically better correlations with weighted Mohs hardness value of rock minerals (Ha), equivalent quartz content (EQC), and uniaxial compressive strength (UCS), than CAI of dry rocks (CAIdry). The in-situ construction data analyses suggest that the average disc cutter consumption increases exponentially with the rise of CAI values in both dry and saturated conditions, and the water saturation effects significantly reduce the disc cutter consumption within medium-hard and hard surrounding rocks. Both disc cutter and specific energy consumption have a quadratic relationship with the ratio of the maximum cutter spacing to penetration depth (Smax/P), and water saturation can significantly shift the quadratic relationships. Optimal Smax/P ranges for minimizing the disc cutter and energy consumption are recommended for different rocks under dry and saturated conditions. The findings from this study can support estimating cutter and energy consumption with considerations of groundwater effects.

Optimum spacing and rock breaking efficiency of TBM double disc cutters penetrating in water-soaked mudstone with FDEM

Cutter spacing is one of the key factors affecting the rock breaking efficiency of Tunnel Boring Machine (TBM). In the excavation of deep soft rock tunnels, the water content can change the fragmentation behavior by TBM cutters, and further influence rock breaking efficiency. This study takes mudstone as an example to study the influence mechanism of water content on the optimum cutter spacing and rock breaking efficiency when TBM disc cutters penetrate soft rock. Firstly, the FDEM water migration-fracture coupled model considers the water weakening effect based on existing experimental fitting results. Secondly, several numerical experiments are conducted to calibrate the microscopic parameters input in FDEM. Finally, a series of numerical experiments of TBM double disc cutters penetrating in water-soaked mudstones are carried out using the coupling model. The crushing characteristics, cutter force, acoustic emission (AE), and crack pattern with different water content and cutter spacing are discussed in detail. Moreover, a novel recognition algorithm is proposed to calculate the rock chip distribution and area. The crack number, work done by the cutters, and specific energy (SE) are quantitatively analyzed. The results indicate that the water content of 2%–3% and the cutter spacing of 60–80 mm can lead to the lowest SE and highest rock breaking efficiency. Overall, the optimum cutter spacing decreases with the increase of water content. The modeling results can supply guidance for the optimization of cutter spacing during TBM tunneling in water-rich soft rock ground.

Performance improvement strategy of the TBM disc cutter ring material and evaluation of impact-sliding friction and wear performance

Tunnel Boring Machine (TBM) cutter ring is prone to collapse, fracture, wear, and other types of failures when dealing with hard rock/extremely hard rock. In order to address the above issue, performance enhancement strategies including electroslag remelting and increased number of tempering cycles in the heat treatment process have been implemented. These strategies lead to improvements in the comprehensive performance of the cutter rings. To evaluate the effectiveness of these enhancements, a comparison was made between the mechanical properties of the cutter rings made by H13 and W360 steels, based on the parameters including microhardness, impact toughness, and impact-sliding resistance. The results show that the microhardness of W360 cutter ring specimen has increased by 9.99%, while the impact toughness has also increased by 54.2%. According to the impact-sliding wear experiment, the impact region of the W360 specimen has a smaller wear depth under the impact angles, reflecting that the impact resistance of the W360 specimen is better. However, when the impact angle is 60°, the wear volume of the sliding region of W360 specimen is larger than that of H13 specimen, which may be related to the fact that H13 specimen contains a higher proportion of martensite. To sum up, better comprehensive performance could be obtained by choosing a reasonable metallurgical method and an optimizing heat treatment process.

Study on rock-breaking efficiency evaluation of TBM disc cutters based on Rostami prediction equations

As the main cutting tool of Tunnel Boring Machine (TBM) for rock-breaking, the rock-breaking efficiency of TBM disc cutters directly affects the TBM’s boring speed, which in turn affects the overall progress of the tunnelling project. Therefore, a simple and accurate evaluation method of the rock-breaking efficiency of TBM disc cutters is an essential prerequisite to improve the rock-breaking performance of TBM. In this paper, the classical force prediction equations of disc cutters were summarized and the applicability of each equation for the constant cross-section disc cutters was analyzed. The calculation equation of the specific energy per ring of TBM rock-breaking was derived based on the Rostami prediction equations and the specific energy theory for disc cutter rock-breaking. The specific energy per ring equation was verified through a practical engineering case. The results show that the maximum relative error of the effective thrust force and the effective torque of the cutter head based on the Rostami force prediction equations is 9.8%. The relative error of the specific energy per ring is 8.0%, which indicates that the prediction of the specific energy per ring equation can accurately reflect the rock-breaking efficiency of disc cutters. The derived equation of the specific energy per ring can not only simplify the rock-breaking efficiency evaluation of TBM disc cutters, but also serve as a valuable reference for practical engineering projects.

Evaluation of Cutting Performance of a TBM Disc Cutter and Cerchar Abrasivity Index Based on the Brittleness and Properties of Rock

The brittleness of rock is known to be an important property that affects the fragmentation characteristics of rock in mechanized rock cutting. As the interaction between the cutting tool and the rock (i.e., cutter forces, cutting efficiency, s/p ratio, and abrasivity) during mechanical rock cutting is strongly influenced by the characteristics of rock fragmentation, the cutting tools (i.e., disc cutter and pick cutter) experience different cutting behaviors depending on the rock brittleness. In this study, the relationships between the rock brittleness and the abrasivity of rock, and the cutting efficiency of a Tunnel Boring Machine (TBM) disc cutter were investigated for Korean rock types. The brittleness was calculated by the mathematical relations between the uniaxial compressive and Brazilian tensile strengths of the rock. The cutting efficiency and abrasivity were evaluated by the cutter forces and specific energy from the linear cutting machine (LCM) test and the Cerchar abrasivity index (CAI) test, respectively. The results show that rock brittleness is significantly correlated with cutting efficiency and CAI values. Consequently, some prediction models for cutter forces, specific energy, and the CAI were proposed as functions of the rock brittleness.

Numerical study on the rock breaking mechanism of high-pressure water jet-assisted TBM digging technique based on 2D-DEM modelling

In order to improve the digging efficiency of tunnel boring machine (TBM) in high-strength and highly abrasive formations, high-pressure water jet-assisted tunnel boring machine rock breaking technology has been developed and applied in steps. In this study, rock breaking mechanism by the new technology is investigated based on two-dimensional particle flow code (PFC2D) modelling. The force chain field distribution law and crack extension evolution characteristics of three typical rock breaking models are studied, and the influence of precutting slits parameters on force chain field distribution, rock sample rupture pattern, and peak load are further analysed. The results show that: 1) The rock breaking processes of the three typical modelling types (i.e., complete cutting model, same trajectory cutting model, and different trajectory cutting model) are different. Among them, the different trajectory cutting model is more likely to produce tensile failure and effectively reduce the penetration depth required for rock breaking. 2) The percentages of tension cracks to the total cracks in the three typical modellings are 90.8%, 93.9%, and 89.8%, respectively, indicating that the above three models are dominated by tension damage in the mesoscopic view. 3) With the increase of the depth of the precutting slit, the depth of the stress concentration zone beneath the disc cutter increases, inducing the increase of the angle between the edge of the stress concentration zone and the upper surface of the rock sample. Meanwhile, the peak load decreases, hence the difficulty of the tunnel boring machine disc cutter penetration is gradually reduced.

Rock Crushing Analysis of TBM Disc Cutter Assisted by Ultra-High-Frequency Loading

In the construction of mountain tunnels, the increasing proportion of hard rock stratum enhances the difficulty of rock breaking by tunnel boring machine (TBM). As a type of cyclic load with ultrahigh frequency, ultrasonic vibration has the advantages of energy concentration and strong penetration. In the process of rolling and extrusion, the weakening of the rock by ultrahigh-frequency loading can improve the rock crushing efficiency of the TBM disc cutter. In this study, we established a physical model of rock cutting using a disc cutter assisted by ultrasonic vibration and obtained a motion equation. The discrete element software particle flow code (PFC) was selected to construct a heterogeneous granite model to demonstrate the mechanism and development of cracks inside the hard rock under a rolling disc cutter assisted by ultrasonic vibration. The results demonstrate that ultrasonic vibration helps the disc cutter construct a stronger stress field in the shallow layer, which promotes tensile damage of the surface rock. Vibration promotes the development of cracks inside the rock and accelerates the penetration of transverse cracks, which is conducive to the stripping of rock fragments. The addition of ultrahigh-frequency loading also reduces the fluctuation increase of cracks, which makes the operation state of the disc cutter more stable and avoids abnormal damage to tools.

Spacing Optimization of the TBM Disc Cutter Rock Fragmentation, Based on the Energy Entropy Method

We used the hyperbolic Drucker–Prager and damage-failure models to simulate a three-dimensional rock fragmentation with a tunnel boring machine (TBM) disc cutter through ABAQUS. The energy entropy method was proposed to identify the optimal disc cutter spacing. In order to verify the results of the numerical simulation, previous linear cutting machine (LCM) test data were referred to. The results of the numerical simulation were verified by comparing the mean rolling force and the specific energy against the corresponding values from the LCM tests. The proposed energy entropy method showed a good agreement with the LCM test results, thus proving its usefulness in analyzing rock fragmentation for various disc cutter spacings. The comparison between energy entropy and the specific energy showed that both methods provide similar conclusions with regard to optimal spacing. The results of this research showed that energy entropy can predict the performance of TBM disc cutters and could help improve their design.

Comparison of DEM Models with Different Elemental Dimensions for TBM Disc Cutter Rock Fragmentation

Disc cutters are the dominant tool used in the excavation of hard rock formations in any underground construction application, such as when tunneling using tunnel-boring machines (TBM), as well as in shaft- and raise boring operations. Optimization of the cutting geometry of a given disc cutter for application in a rock formation often involves full-scale cutting tests, which is a difficult and costly proposition. An alternative to full-scale testing is the numerical simulation of TBM disc cutters for optimization under different settings. Recent efforts in the field of numerical simulations of rock cutting have shown the relative success of discrete element models, such as particle flow code (PFC), to simulate two- and three-dimensional rock fragmentation. This study is focused on a sensitivity analysis of PFC simulation of rock-cutting relative to the size of the elements. The calculated cutting forces were compared with the recorded forces under various conditions during full-scale tests using a linear cutting machine (LCM) on Colorado red granite (CRG). The estimated cutting coefficient and specific energy in the LCM tests and simulations showed good correlations, which validates the numerical simulation results. Two- and three-dimensional models showed that two-dimensional numerical models can offer a qualitative assessment of crack development, whereas three-dimensional models could be used to estimate the specific energy when cutting. The results can help in predicting the cutting forces in different rocks and ultimately improving disc-cutter geometry and cutter-head design.

Assembly Deviation Analysis of New Integrated TBM Disc Cutter and Design of the Supporting Cutter-Changing Robot End-Effector

At present, the replacement of disc cutters of the tunnel boring machine (TBM) is a very important and difficult manual operation. It is meaningful to study disc cutters of TBM replacement with a robot. In this paper, the machining and assembly deviation of the new integrated disc cutter developed by our research group is modeled and analyzed using the improved Jacobian–Torsor model, and the analysis results are verified by experiments. On this basis, aiming at the possible radial deviation and angle deviation in the working process of a robot replacing TBM disc cutters, a cutter-changing robot end-effector composed of a guiding mechanism, a flexible connecting mechanism and a universal wrench is designed for the disassembly and assembly of the new integrated disc cutter, and scaled-down models were made for the experiment. The test results show that when there is a radial deviation of 19.21% or an angle deviation of 11° between the fastening bolt and the end-effector of the robot, the robot end-effector can complete the docking with the fastening bolt.

Effect of Impact-Sliding Angle on the Wear Performance of the H13 Steel of a Tunnel Boring Machine Cutter

Tunnel boring machines (TBMs) are widely used in tunneling engineering. Due to the harsh and complex working conditions, the TBM disc cutters suffer extensive wear, resulting in large economic losses. Among many influencing factors, the contact angle between the rock and the cutter significantly influences the cutter ring. In this study, the composite wear properties of the cutter base material (H13 die steel) were investigated at different impact-sliding angles to determine the wear mechanism. The results show that the damage to the impact region of a flat sample is primarily caused by the large contact stress generated by the high-strength instantaneous impact. The damage is positively correlated with the impact-sliding angle. As the contact angle increases, the contact duration during the sliding process increases, and the area of the flat sample with the most damage changes from the impact region to the start of the sliding region. In addition, the wear mechanism of the flat sample changes from abrasive wear to mixed abrasive and adhesive-fatigue wear. This work is a fundamental study of the microscopic wear mechanism of the H13 steel, which is used in the TBM cutter. Therefore, the results reflect the wear conditions of the TBM cutter at different contact angles and provide significant guidance for the installation of the TBM cutter.

Investigation on Two-Step Simulation Modeling Method for Rock Breaking by TBM Disc Cutters Assisted with Laser

Considering that conventional experiment methods are time-consuming, laborious and expensive, on the premise of understanding the rock fragmentation mechanism of disc cutter cutting and laser drilling respectively, a novel simulation modeling method of rock breaking of tunnel boring machines (TBM) disc cutters assisted with the laser is proposed. The method includes two-step modeling features: 1) in the first step, a finite element model of laser drilling is established in ANSYS, and then the morphology of a single hole and fissures can be predicted using the birth and death element method; 2) in the second step, a rock finite element model with multiple holes is reconstructed in HyperMesh, where the holes with a given hole spacing n have the same shape as the first step; then, ANSYS/LS-DYNA is used to carry out the simulation analysis, thereby indirectly simulating rock breaking process of TBM cutters assisted with laser. Finally, to demonstrate the applicability of the method, a simulation case study is carried out and the obtained values such as cutting force, the amount of rock breaking, and specific energy consumption are according with theoretical expectations. It can be seen that this paper provides an economical and feasible solution for the study of laser-assisted rock breaking.

Prediction and analysis of slurry shield TBM disc cutter wear and its application in cutter change time

Disc cutter is mainly used in cutting through hard rock. Disc cutter wear is inevitable during tunnel boring machine (TBM) tunneling, and excessive wear can lead to a decrease in tunneling efficiency and increase construction risks. Therefore, the importance of predicting the disc cutter wear accurately and arranging the cutter change plan can never be overemphasized. In this study, disc cutter wear data and replacement records for three shield chamber openings were analyzed, which were collected from a water conveyance tunnel project in Guangdong, China. It was found that the normal wear failure accounted for approximately 76.19%, while the abnormal wear failure accounted for 23.81%, and the range of tools to be replaced due to normal wear continues expanded as the tunneling distance increased. Based on the observed wear data, it is found that the wear rate of edge tools is much lower than that of center tools, which does not conform to the normal wear rules. Subsequently, a new disc cutter wear prediction model was developed considering energy conversion and uneven thrust distribution for explaining this problem. The determination method of the energy conversion coefficient k and thrust distribution coefficient b was proposed, and they had been obtained from the wear data in the first replacement. On the other hand, the proposed model has higher accuracy in both cutter wear and cutter change range prediction compared with the existing models. However, the prediction accuracy of the proposed model will decrease with the increase of the tunneling distance, so the undetermined coefficients k and b need to be updated in a timely manner.

Impact-sliding behavior of Ni-based coating prepared on tunnel boring machine disc cutter material produced using a plasma transferred arc welding process

The working condition of the disc cutter of the tunnel boring machine (TBM) is extremely harsh and is severely worn during the rock-cutting and tunneling process. Reducing the wear rate of the cutter and extending the service life of the cutter are essential to improving the economic costs and safety of the TBM. This article explores the feasibility and effectiveness of using surface coatings to improve the wear resistance of the cutter ring. NiCrBSi/WC coatings with different current intensities were prepared on the disc surface using plasma surfacing technology. The wear performance of the coating was evaluated using a bespoke impact-sliding device that fits the actual working conditions, and the wear mechanism was studied in detail. According to the “tadpole-like” wear scar characteristics of the coating after the impact-sliding wear experiment, the wear scar zone can be divided into two regions: the impact region and the sliding region, which are consistent with the actual wear characteristics of the cutter ring. In addition, the wear behavior of the coating noticeably changed under each experiment parameter, and the evolution process of the impact-sliding wear of the gage cutter at each position can be well reproduced. When the impact angle was 45°, the wear depth and wear volume of the coating were significantly smaller than those of the uncoated samples. This is mainly due to the metallurgical bond between the Ni-based alloy zone (binder phase) and the spherical WC particles (hard phase) on the surface of each specimen. When impacted by the tribo-ball, the WC particles can undergo plastic deformation and relaxation through the Ni-based alloy zone under the applied force, thereby obtaining excellent impact and sliding resistance. When the impact angle was 60°, the impact dominates, causing the impact force to increase. Furthermore, compared with the uncoated specimens, the wear depth and wear volume of the coated specimens significantly increased, indicating that the anti-impact ability was seriously degraded in such situation. In summary, the powder composition and preparation process parameters should be reasonably selected according to the impact angle, and the impact-sliding wear experiment can effectively evaluate the impact and sliding wear performance of different coatings. This approach has an important directive function in the promotion and application of cutter ring coatings.

Statement of Retraction: Modelling and Simulation of Surfacing Welding Remanufacturing for Tunnel Boring Machine Disc Cutter

Statement of Retraction: Modelling and Simulation of Surfacing Welding Remanufacturing for Tunnel Boring Machine Disc Cutter

Dynamic Rock-Breaking Process of TBM Disc Cutters and Response Mechanism of Rock Mass Based on Discrete Element

Rock-breaking efficiency of full-face rock tunnel boring machine (TBM) is closely related to the performance of the disc cutter and the characteristics of the rock mass. In the point of view of mesomechanics, the particle flow code (PFC) is used to establish a numerical model of the rock mass and the disc cutter, and the process of TBM disc cutter intrusion into the rock mass is analyzed. The dynamic response mechanism and crack evolution process of the rock mass under the action of the disc cutter are studied on the basis of micromechanics, and the relationship between the rock mass crack, penetration, and cutting force during the intrusion of the disc cutter is revealed. The sensitivity analysis is carried out on the confining pressure conditions and the influence parameters of the disc cutter spacing. The results show that the rock breaking by disc cutter undergoes the transformation characteristics of compaction, shearing, and tension failure modes, and the failure process of the rock mass is the joint action of tension and shear. In the whole process of rock breaking, the disc cutter has the phenomenon of repeated loading-unloading alternation and leaping rock breaking; after the penetration of the disc cutter reached 9.0 mm, penetration creaks begin to appear on the surface of the rock mass; the penetration was obviously reduced with the increase of confining pressure, and it is mainly the penetration cracks on the surface; after the disc cutter spacing reaches 100.0 mm, there is no penetration crack between the two disc cutters. The research conclusion can provide a reference for the disc cutter optimization design.

Full-Scale Cutting Experiments of Different Granite Integrity Using Tunnel Boring Machine Disc Cutter

Full-Scale Cutting Experiments of Different Granite Integrity Using Tunnel Boring Machine Disc Cutter