Study On Rock Breaking Mechanism And On Influencing Factors Of Cutters Performance

The hard rock Tunnel Boring Machine is always used in the rapid tunnel project for its advantage such as fast speed, good quality, and safety and economic. It has a lot of market with the growth of more projects in hard rock, which will need higher quality of the TBM especially on the disc cutter quality and long lifetime.The most cost in the project is the disc cutter cost, which is lot relationship with the efficiency and boring difficult degree. The most stop in the project is the reason for changing cutter tools. And the best solution to deduce the project cost is to deduce the wear and damage of thecutter tools on order to improve the cutter lifetime.The liner cutting method is firstly used to test the boring mechanism and influencing factors of cutters performance in China. And this paper is mostly focus on the boring mechanism and the boring forces and mass according to different boring parameters through the high speed camera shooting technique, simulation and industrial test method. We built the first liner cutting test equipment in China, and a lot of tests were done on this machine. We expected to find the boring parameters’influence law on the boring forces and mass through comparing the test data and project data.The main research work and achievements are as follows:Firstly, we studied the boring mechanism and roch failure rules, and then built three kinds of simulaton model under RFPA simulation environment. We also did a lot of tests using the high speed camra shooting system to make sure about the rock boring mechanism. We can easily find that the boring process is divided into three parts, initial deformation, crack formation, crack grow and rock separation.Secondly, the force model was simplified before building the autodyn simulation model. We can find the cutter influence on the rock around and calculate the boring forces from the simulation. And the test result figured out the fracture mechanism in the microcosmic angle under different disc cutter structure parameters, boring parameters and rock type.Thirdly, we ansysis the displacement offset caused by rock heterogeneity during rock boring test on the liner cutting test platform, and summarize the affecting law by different boring parameters.We tested the significantly influence of the boring parameters on boring forces. It’s found that the penetration is the most important factor, the cutting speed influences crack growth rate, and the cutter space directly affect the size of the fragments. The optimal level and the optimal combination for granite cutting were also obtained.Forthly, we tested a list of single factor test according to penetration, boring speeds,and cutter spaces, and find the optimal penetration, boring speed and cutter spaces in current boring granite through comprehensive comparison of boring forces, mass, rock surface morphology, fracture rock size,etc.Lastly, the cutter wear predicting model was built, then the cutter wear was studied through theoretical calculation and test method and the wear law according boring distance was summarized. And the cutter replacing frequency was recorded on different layout of the Yintao project. The side cutter was more easily wear for long boring distance.