Evaluating the Effect of Tool Wear in Soft Soil Using New TBM Tunneling Simulator Device

Abstract

Abstract Cutting tool resistance to abrasion are among the most important factors in the efficiency of earth pressure balance (EPB)–tunnel boring machines (TBMs). Excessive wear negatively affects the operating parameters of the tunneling machine and reduces its efficiency. Considering the lack of a comprehensive and accepted method for the study of wear in soft grounds, this study sought to design and manufacture a TBM tunneling simulator to better understand the interaction between soil and cutting tools. For this purpose, after introducing a new machine manufactured in Sahand University of Technology (Tabriz, Iran), the effect of the density of two types of soil with different granulation and moisture on the wear of cutting tools under different conditions was investigated to simulate the TBM tunneling mechanism. The low rotational speed of the cutterhead (similar to EPB machines), continuous contact of the cutting tool with the intact soil, continuous injection of conditioning additives with specified injection pressure during the test, and horizontal operation similar to TBM are the most important features of this machine. The results indicated that an increase in the soil density from 1.5 to 2.0 g/cm3 at a moisture content of 7 % increased the maximum wear of cutting tools from 4.1 to 11.6 %. Accordingly, a similar trend was observed for moisture of 13 %. By studying wear at different densities and percentages of moisture, a decreasing trend of wear was observed under the same conditions at a higher moisture percentage. Furthermore, increasing the soil density initially increases the wear of cutting tools, although a further increase in the density causes clogging in the cutterhead, and no significant changes were observed in the amount of wear in this area. Finally, the results of some operational tests show that increasing the penetration rate and rotational speed of the cutterhead can decrease and increase tool wear under different conditions, respectively.