| TBM(tunnel boring machine),i.e.full face road header,is a kind of tunneling equipment that carries out rock breaking,rock loading,slag discharge and support simultaneously.TBM has been widely used in energy,transportation,water conservancy,municipal engineering and other fields because of its advantages of good safety,fast tunneling speed and high degree of mechanization.TBM uses cutter to break rock,and its rock breaking efficiency is greatly affected by geological conditions.The rock breaking characteristics of cutter in composite rock stratum are quite different from those in homogeneous rock stratum.In order to reveal the rock breaking mechanism of TBM in composite rock stratum and provide a theoretical basis for the optimization of TBM tunneling parameters in composite rock stratum,the research work on loading speed,tool moment and crack is carried out in this paper.The main research work and conclusions are as follows:(1)The physical and mechanical properties of quasi composite rock samples were tested to obtain the physical and mechanical parameters of quasi composite rock samples.The numerical models of uniaxial compression and Brazilian splitting are established by PFC2D numerical simulation software.Based on the physical and mechanical parameters of two kinds of composite rock samples,the micromechanical parameters of particle flow are calibrated.(2)The numerical test of rock breaking by composite rock cutter was carried out.The numerical model of rock breaking particle flow of cutter is established by PFC2D.The distribution and evolution mechanism of normal force,crack and particle contact number in the process of rock breaking are explored by changing the loading speed and moment between cutters.It is found that the crack propagates and develops in the process of rock breaking by cutter.When a single cutter breaks rock,the loading speed is within a certain range.With the increase of loading speed,the maximum normal force of cutter tends to increase.The rock breaking efficiency is the best when the inter cutter moment is 40mm,and the critical normal force is the largest under this inter cutter moment.(3)The existing pressure testing machine design is transformed into an experimental platform,and the rock breaking similar model experiment of TBM cutter is carried out to study the damage and failure characteristics of composite rock under the rock breaking condition of cutter,and reveal the rock breaking mechanism of composite rock cutter.It is found that the variation trend of cutter normal force with penetration obtained from test and simulation is generally consistent.The maximum cutter normal force obtained by simulation is greater than that obtained by test,and the amplitude of the normal force obtained by test with the increase of penetration is less than that obtained by numerical simulation.There is not enough confining pressure and experimental error in the actual experiment,resulting in the value obtained from the experiment is slightly smaller than the data obtained from the simulation.Through the above research work,the numerical model of rock breaking particle flow of Composite Rock TBM cutter is constructed,and the numerical test of rock breaking of Composite Rock TBM cutter and the similar model test of rock breaking of TBM cutter are carried out.The critical normal force and rock failure characteristics of composite rock under different loading speed,cutter number and moment between cutters are obtained.It can provide reference for TBM excavation,parameter optimization and TBM cutterhead optimization design in composite rock stratum.Figure 58 Table 14 Reference 77... |
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