The Rolling Indentation Abrasion Test (RIAT) - NTNU/SINTEF's new approach to tool life assessments on hard rock tunnel boring
Cutter consumption plays a significant role in performance and cost during TBM tunnel boring especially in hard rock conditions. Reliable assessments of cutter consumption will facilitate the control of risk as well as avoiding delays and budget overruns. The new NTNU/SINTEF abrasivity test method RIAT (Rolling Indentation Abrasion Test) has been developed to reproduce wear behaviour on hard rock TBM tunnel boring (Macias et al., 2015, 2016; Macias, 2016). The RIAT procedure introduces wear by rolling contact on intact rock and the achieved results indicates a great ability of this new test method to assess abrasive wear on rolling discs. There are several laboratory test methods (CAI, AVS, LCPC) which are traditionally used to assess cutter consumption. None of them were originally developed for TBM cutter wear assessment, as they uses sliding or impact contact in order to cause wear. The question is hence whether they are able to reproduce the wear behaviour encountered during TBM tunnel boring in a realistic way. The RIAT should however, by introducing rolling contact on intact rock samples, be able to asses cutter wear in hard rock TBM tunnelling as close to reality as possible in a down scaled test. The main advantages of the RIAT are: wear caused by rolling contact, testing of intact rock samples, relatively small samples needed, cost effective method and in addition, a simultaneous measurement of the rock indentation resistance or rock surface hardness.