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

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.