| TBM is widely used in tunnel construction in recent years due to its advantages of high efficiency,quickly speed,safety,environmental protection and high quality.Compared with engineering practice,theoretical research on TBM is relative lag.Especially when it comes to the mechanical behavior of rock breaking of cutters,its mechanical interaction with cutters,the influencing factors of rock breaking of cutter head,the formation adaptability of TBM and the rapid tunneling parameters of TBM under different surrounding rock conditions,there is no unified understanding on these technical problems.Based on the diversion tunnel in Nepal,this thesis focuses on the rock breaking mechanical behavior of cutters,the interaction relation among cutters,the influencing factors of rock breaking by cutter head,the stratum adaptability of TBM and the parameters of rapid tunneling with the program ‘research on key technology of rapid excavation of double shield TBM in the water diversion(small section)extra-long tunnel’.Five methods,such as data research,laboratory test,theoretical analysis,numerical simulation and field data analysis,are used together to study the Rock breaking mechanical behavior of cutters,the interaction analysis of cutters,the analysis of influencing factors of rock breaking of cutter-head,the formation adaptability of TBM and the optimization of rapid excavation parameters.The main contents are as follows:(1)After establishing the principle of TBM equipment selection,comparing and analyzing the differences and advantages and disadvantages of the single and double shield TBM,combined with the engineering conditions,the construction plan using the double shield TBM was determined.A systematic comparative analysis of different types of TBM equipment components shows that the Robbins double shield TBM was the optimal excavation machine for this project.(2)Based on the three-dimensional particle discrete element method,combined with laboratory mechanics experiments,the particle flow calibration tests were carried out on the mudstone and sandstone in different sections of Siwalik,and the relationship between the macroscopic mechanical parameters and the microscopic parameters of particle flow was established.The mechanical behavior of rock breaking by cutters at different position of cutter head is analyzed and studied,and the feasibility of discrete element method is verified by comparing prediction model and tunneling parameters on site.Meanwhile,the interaction relation of cutters is studied.(3)From the three influencing factors of penetration degree,rotation speed of cutters and rock strength,the rock breaking force of cutter-head of TBM was deeply studied,and the saliency of three factors was analyzed by orthogonal test.Combined with the excavation parameters of TBM on the construction site,statistical analysis was carried out on the excavation parameters,and the correlation between the excavation parameters and the reasonable excavation parameters of different strata were analyzed to find out the formation adaptability of TBM excavation.(4)The solution method of rapid excavation parameters was established.The excavation parameters and the discrete element method were used to optimize the excavation parameters of different surrounding rock conditions in Siwalik,and the optimal rapid excavation parameters under the surrounding rock of grade Ⅲ,Ⅳ and Ⅴ were obtained. |
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