盾构切削混凝土刮刀受力和磨损的离散元数值模拟研究

Numerical Simulation Study on Forces and Wear of Shield Scrappers used for Concrete Cutting by Discrete Element Method

随着城市隧道建设过程中盾构切削混凝土基础案例逐渐增多,研究盾构刮刀在切削混凝土过程中的受力和磨损对于保障盾构安全高效掘进、拓宽盾构机适用范围意义重大.在前期试验的基础上,利用离散元软件EDEM,对刮刀切削混凝土过程进行了数值模拟,研究了刀具参数(刀具前角、刀具后角、刀具形状)、试件强度、切削深度和切削速度对刀具受力的影响,并基于Archard模型探讨了刀具的磨损情况.计算结果表明,刀具前角越大,刀具受力越小;刀具后角和形状对其受力影响较小;试件强度、切削深度和切削速度越大,刀具的受力越大.数值计算得到的刀具切削力平均值与室内试验结果总体上有很好的一致性.刀具磨损情况最为严重的部位是刀尖;刀具前、后角越大,刀具磨损越严重;刀具磨损随切削深度、试件强度、切削速度的增大而增大.研究成果可为盾构刮刀设计和选型提供参考.

In recent years,cases of using shield machines to cut concrete foundations during urban tunnel construction have been increasing steadily.It is of great significance to investigate the forces and wear of the shield scrapers for the safety and efficiency of shield tunneling and the expansion of the shield machine application.Based on the previous tests,numerical simulations of using scrappers to cut concrete are performed by using the software EDEM.And the effects of the cutter parameters(the tool rake angle,tool relief angle,and tool-tip shape),the sample strength,the cut depth,and the cutting speed on the forces acting on the scrapers are investigated.And wear of cutters is also discussed based on the Archard model.Calculation results show:1)The force on the cutters decreases with the increase of the tool rake angles.2)The tool relief angles and the tool-tip shapes have a small influence on the forces on the cutters.3)The force on the cutters increases with the concrete sample strength,the cut depth,and the cutting speed.The averaged calculations of the forces have good agreement with the results attained from the tests on the whole.The most worn part is the cutter tip;more serious cutter wear is observed when subjected to a larger tool rake angle;the cutter wear amount increases with the increase of the concrete sample strength,the cut depth,and the cutting speed.The findings can provide good references for shield scrapper design.