A new cutter wear testing method for evaluating the plowing effect of ripper tooth during shield TBM tunneling in abrasive sandy ground

• A new cutter wear testing method is developed for evaluating the plowing effect of ripper tooth. • The plowing coefficient is proposed to quantify the influence of plowing effect on scraper wear. • The influence mechanism of plowing effect is revealed based on excavation process analysis. • The height difference between ripper tooth and scraper is optimized for sandy ground tunneling. When shield TBM tunneling in dense sandy ground, the installation height of the ripper tooth is higher than that of the scraper. The ripper tooth plows the excavation surface, followed by the scraper cutting the loose sand. The plowing effect refers to the mitigation of scraper wear by the ripper tooth, which loosens the dense sand on the tunnel surface. Although it has been analyzed qualitatively over the past few decades, there is still a lack of reliable parameters for quantitative evaluation. The influence of cutter height difference, sand density and particle size on plowing effect is unclear. In the present study, the WHU-SAT test apparatus that can continuously change cutter height difference was developed to explore plowing effect of ripper tooth. The plowing coefficient was proposed to quantify the plowing effect on dense sandy ground. The influence mechanism of cutter height difference, sand density and particle size on plowing coefficient was revealed based on excavation process analysis. The cutter height difference between ripper tooth and scraper was optimized for dense sandy ground tunneling. The results indicate that as cutter height difference increases, the loosening depth of ripper tooth on tunnel face increases. The bulk density of sand samples cut by scraper decreases first and then stabilizes, leading to a similar trend in the plowing coefficient. With the increase of sand density, the loosing depth corresponding to the stable plowing coefficient increases first and then stabilizes, resulting in a similar pattern for the optimal cutter height difference. As the average particle size increases, the loosing depth corresponding to the stable plowing coefficient increases, leading to an increase in the optimal cutter height difference. The present study provides a reference for optimizing cutter height difference in dense sandy ground tunneling.