Effect of Blade Angles on the Shovel Muck Capacity and Wear Characteristics for TBM Scraper

During tunnel boring machine (TBM) excavation, scrapers play the role in shoveling the broken rock fragments, directly contacting with them, which may result in seriously wear and failure, causing high economic loss. Therefore, it is an urgent problem to study the wear mechanism of scraper and how to reduce the blade wear. In this study, the wear prediction model of scraper was established based on working mechanism and wear mechanism analysis. The factors influence on wear characteristic were obtained. Then, the numerical model of TBM scraper shoveling the muck was established using discrete element method. The shovel capacity and wear characteristic of scraper were studied. The structural parameters of blade were optimal designed, comprehensively considering the shovel capacity and wear characteristics. The results indicate that abrasive wear is the main type of scraper wear. The main influencing factors of scraper wear are blade angles. When the front angle of the blade is 25° and the back angle is 8°, the wear performance of the scraper would be improved. The optimal results were successfully applied to a tunneling project and the actual data in the engineering construction of the scraper during the construction were analyzed to verify the structural design method of TBM scraper.