Abstract
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.
Highlights
Full-face rock tunnel boring machine (TBM) has been widely used in mining engineering, water conservancy and hydropower tunnels, highway tunnels, and other projects.e disc cutter, at the foremost end of TBM, is an important part of TBM, which determines whether it can effectively break rock and directly generate load on the surrounding rock to cause dynamic damage to the rock mass
As a numerical simulation method based on discontinuous medium theory and mesomechanics, the particle discrete element method can simulate the failure mechanism of rock materials from the perspective of mesomechanics and simultaneously reflect the micro-mesostructure characteristics and macromechanical behavior of materials. e simulation of the physical prototype by the particle flow method is mainly completed by defining the mesoparameters and macroboundary conditions of particle bonding
In the process of rock breaking, the disc cutter ring contacts the rock, and the rock is penetrated by the pressure of the cutter head, and cracks are generated to achieve the purpose of rock breaking. e commonly used 17-inch disc cutter is adopted, the wall combination is used to simulate the disc cutter ring, and the model is 200.0 mm wide and 100.0 mm high. rough the servo mechanism of the upper and lower walls, preloading consolidation is performed to simulate the natural formation process of the rock mass. e left, right, and bottom walls of the sample are all rigidly constrained to limit the displacement of the rock mass
Summary
Full-face rock tunnel boring machine (TBM) has been widely used in mining engineering, water conservancy and hydropower tunnels, highway tunnels, and other projects. In terms of the interaction between the disc cutter and the surrounding rock, around the rock-breaking mechanism of the TBM disc cutter, the predecessors have carried out relevant research works from the perspectives of theoretical analysis, indoor linear cutting machine test, and numerical simulation [6,7,8,9,10,11,12,13,14,15,16,17]. In terms of rock-breaking simulation with TBM disc cutter, the particle discrete element method focuses on the analysis of the damage and fracture mechanism of materials from the perspectives of the mesoscale mechanism, which can realize the numerical experiment and analysis of the mesobrittle fracture mechanism and progressive failure process of rock materials [39]. The influence of the confining pressure conditions and the disc cutter spacing on the rock crack properties, quantity, disc cutter reaction force, rock-breaking effect, etc., are further simulated and analyzed. e research results can provide a reference for TBM type selection and disc cutter design
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
