Research On Rock Fracture Mechanism Under Disc Cutters And Cutter Layout Optimization

As a kind of fast, efficient, safe, economic underground engineering equipment,Tunnel Boring Machine(TBM) is widely used in our country and rapidly developed. Disc hob as the main tool to break rock in the process, the crushing efficiency directly affect the underground project construction efficiency and cost. Practice proves in the hard rock TBM geological condition, the cost of the tools is about a third of the construction cost. So the crushing mechanism of rock further research is a theoretical value and engineering significance. The cutter layout design is the key of TBM design, its tunneling effect is the decisive factor of performance. The layout of cutting tool is significant factor, that influence tool rock fragmentation efficiency, force balance of work, the stability of the knife dish, the load distribution among the uniformity of the working plane and stability of performance of the important factors. It is necessary to optimize layout tools. This paper main research work is below:(1) rock crushing mechanism and hob bearing model under the action of hob: summarized the hob structure and type selection, summarized the hob force prediction model, study the rock mechanics properties, rock damage phenomenon and failure mechanism, constitutive relation of rock subtle statistical damage model, analyses the disc hob broken rock mechanism, the theoretical foundation for the numerical simulation.(2) simulate rock fracture under single cutter, double cutters and several cutters by numerical simulation method, and the results show that under the effect of hob rock failure process is divided into powder body appear, powder nuclear body formation, lateral cracks formation and propagation, broken block produce four stages. Using several cutters can promote the crack growth and penetration. Analysis rock failure mode and load data under different conditions (confining pressure, rock strength, knife section, and the distance of the sword), and concludes that the efficient and reasonable broken rock conditions and parameters.(3) LS-DYNA simulates continuous process of rock broking by disc hob and gets stress and strain in the whole process.(4) establish the optimization model of the cutter layout, using genetic algorithm is proposed to solve the optimization model of cutter layout, and compared with the current layout of cutter, all the indexes have greatly improved, that verified the optimization model is feasible and effective.