刃形对硬岩地层中TBM滚刀磨损行为的影响研究

Influence of Cross-Section Profile on Wear Behavior of TBM Cutters in Hard Rock Stratum

全断面隧道掘进机(TBM)是用于长大隧道建设的关键装备,在公路铁路、引水输水等国家重大战略工程中发挥着重要作用.盘形滚刀位于TBM最前端,是执行破岩掘进的关键零部件.冲击重载和缺少润滑等恶劣工况条件导致滚刀在面对硬岩地层时磨损速率极高,频繁更换刀具对隧道建设的工期、成本和安全性造成严重负面影响.对滚刀磨损机理的深入研究是建立长寿命高性能滚刀设计方法的必经之路.滚刀截面形状以及表面结构是刀-岩接触行为的决定性因素之一,而接触行为对滚刀磨损存在直接影响,但机理机制尚不十分清楚.本文中使用高强度花岗岩开展滚刀磨损试验,针对工程实际中最常用的平顶与圆顶滚刀,研究不同刃形滚刀在磨损过程中切削力、质量损失和表面形貌演变的规律,并结合有限元数值仿真,揭示滚刀刃形通过改变刀-岩接触状态而影响其磨损行为的机理.结果表明,在通过相同距离时平顶滚刀直径变化量小,即达到磨损极限时行进总距离更长、耐磨性更好.圆顶滚刀接触应力集中效应明显,容易发生局部磨损,使圆顶滚刀半径变化更大;但在相同刀盘推力下,圆顶滚刀侵入岩石的深度大于平顶滚刀,在破岩效率方面具有潜在优势.本研究对工程实际中滚刀选型与设计具有重要指导意义.

Tunnel boring machine(TBM)is one of the key equipments used in long tunnel construction,which plays an important role in Sichuan-Tibet railway and other major national strategic projects.Disc cutters are located at the front end of TBM,which directly contact with rock.Harsh working conditions such as heavy impact and lack of lubrication lead to high wear rates of cutters when facing hard rock stratum.Frequent tool replacement has a serious negative impact on the construction period,cost and safety of tunnel projects.In-depth research on cutter wear mechanism is essential for the establishment of design method of long life and high-performance cutters.The cross-section profile of the cutters is one of the decisive factors of the cutter-rock contact behavior which has a direct influence on the cutter wear,but the relevant research is rare.In this work,the cutter wear experiments were performed by using the granite,and the most commonly used cutter profiles,flat-top and circular-top cutters were considered.The effects of cutter profile on cutting force,mass loss and surface morphology evolution were investigated.With the assistance of the finite element simulations,the relationship of contact status and wear behavior was further revealed.The results showed that when passes the same distance,the flat-top cutter had a smaller change of diameter,that was,when the wear limit was reached,the total distance was longer and the wear resistance of the flat-top cutter was better.The contact stress concentration effect of circular-top cutter was obvious so local wear was easy to occur,which made the radius of such cutter decreased more.However,under the same normal force,the circular-top cutter penetrated deeper into rock than the flat-top cutter,which had a potential advantage in rock breaking efficiency.This research had important guiding significance to the selection and design of cutter in engineering practice.