挖泥船绞刀挖岩过程的数值模拟

Numerical simulation of rock cutting process for the cutterhead of cutter suction dredger

针对挖泥船绞刀挖岩过程中绞刀切削力难以预测的问题,本文应用有限元方法建立了模拟绞刀挖岩过程的三维分析模型。采用罚刚度的接触约束算法确定绞刀与岩体的接触状态和接触作用力,利用扩展的DruckerPrager塑性模型以及包含单元删除功能的损伤演化模型模拟岩体变形及破碎,从而获得了绞刀挖岩过程中绞刀的切削力,并进行了实验验证。结果表明:绞刀转速恒定时,切削载荷和功率均随绞刀横移速度增大而显著增大;绞刀横移速度恒定时,功率随转速增大而增大,但切削载荷却有所下降;适当降低绞刀转速和提高横移速度有利于降低岩石切削比能。这些结果可为新型挖泥船绞刀设计提供参考。

During rock excavation process of cutter suction dredger,it is difficult to predict the cutting forces of the cutterhead. In this paper,a 3 D finite element model was established to simulate the rock cutting process by the cutterhead. The contact constraint algorithm combining penalty stiffness was chosen to determine the contact state and contact forces of reamer and rock. The extended Drucker-Prager plastic model was selected for the rock concerning its material nonlinearity. The deformation and fragmentation of rock were simulated by using progressive damage and failure rules,which contain element deletion functions. Based on the above established models the cutting forces of the cutterhead during rock excavation process were obtained and were verified by experiments. The results show that when keeping the rotation rate of cutterhead constant,both cutting load and power increase significantly along with the increase of swing velocity. When keeping swing velocity of cutterhead constant,the power increases along with the increase of rotation rate,whereas the cutting load decreases slightly. Furthermore,it is conducive to reducing cutting specific energy if the swing velocity is increased and the rotation rate is decreased properly. These results can provide reference for the design of a new type of cutterhead used for dredger.