采用数值模拟技术并借助于大型有限元软件,选择在Ottosen四参数破坏准则基础上引入损伤因子的非线性弹塑性本构模型作为软岩的材料模型,建立盾构刀具切削软岩的二维简化模型,模拟破岩过程中裂纹的生成和扩展;建立三维有限元模型,分析切削力在整个切削过程中的变化,并通过试验验证仿真过程的可行性和有效性.研究结果表明;岩石的破碎过程和切屑的形成过程是由拉伸裂纹和剪切裂纹延伸而成;刀具的切削力与切削时间之间遵循波动变化关系,能够较真实地反映盾构刀具破岩过程中岩石的破碎动态响应过程;采用该方法研究刀具几何参数和切削参数对切削力的影响程度和趋势,为盾构刀具的最优化设计提供了参考依据.%By means of simulating technology and functional finite element method, the nonlinear elastic-plastic constitutive model was chosen as the material model of soft rock based on the Ottosen four parameters failure criterion by introducing the damage factor. A simplified 2-D finite element model to simulate cracks generation and propagation in the cutting process was developed using finite element analysis. By building a 3-D finite element model, the change of cutting force during the whole cutting process was analyzed. The feasibility and effectiveness of the method were also verified by experiment. The influence and tendency of tool geometry and cutting parameters in cutting force were analyzed by finite element method. The results show that the fragmentation process of rock or chip formation is caused by the propagation of tensile and shear cracks. The cutting force and time follow a fluctuation variable relationship,which reflects the dynamic fragmentation response process of soft rock in fragmentation by shield cutter in practical. It provides reference for the further optimization design of shield cutter.
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