盾构机切刀切土过程的有限元模拟分析

Numerical Simulation for Breaking Soil Process of Cutting Blade on Cutterhead of Shield Machine Using Finite Element Analysis

采用有限元方法数值模拟了盾构机刀盘切刀的切土过程。采用Drucker-Prager本构模型表征土体的非线性变形特性。讨论了如何将土体直剪实验得到的抗剪指标参数转换为ABAQUS软件的3个塑性指标的方法。有限元分析结果仿真再现了在刀盘切刀作用下的土体破碎过程。在开始时刻,在切刀与土体的接触面产生较大的应力。随着切刀的继续向前推进,最大等效应力位置已经转移到切刀前方大约45°方向。研究结果表明,在切刀启动阶段,切刀切土阻力近似为平稳阶段的4倍。本研究可以为刀盘切刀的优化布置和盾构机掘进参数的合理设定提供借鉴和参考。

The breaking soil process of cutting blade on cutterhead of shield machine is investigated using finite element analysis. Drucker-Prager constitutive model is used to characterize mechanical behaviors of soils. The three plastic parameters in ABAQUS software are derived from direct shear tests for soils. The numerical computing results reproduced breaking soil process of cutting blade on cutterhead. The high stress is induced at the contacting surface between cutting blade and soil at the beginning period. With advancing cutting blade, the direction of maximum Von Mises stress is changed at 45%in front of cutting blade. The investigation shows that the thrusting resistance during starting period approaches to four times of that during normal operation. This study could provide some references for the optimization placement of cutting blade on cutterhead and the reasonable parameters of tunneling shield machine.