Research on rock muck transfer performance of a hard rock TBM cutterhead

Abstract

This study aims to solve the problem of low mucking performance of the large-diameter tunnel boring machine (TBM). The full-scale linear rock-breaking tests were conducted to analyze the size and shape of the rock muck produced under different test conditions. Based on the 3D laser scanning test, the digital 3D model of the real shape of irregular muck was obtained. The numerical simulation of the mucking process of a large-diameter cutterhead was constructed. The influences of the disc cutter system, the degree of joint development, the tunneling direction, and the TBM operational parameters (cutterhead rotational speed and penetration per revolution) on the mucking performance of the cutterhead were investigated. The results indicated that the disc cutter system has the effects of collision and diversion on muck. In the simulation model with the disc cutter system, the amount of the muck in the center buckets increases by a factor of 2.5. In the stratum with a high degree of joint development, the percentage of muck accumulated in front of the cutterhead and inside the cutterhead increases by 22% and 88%, respectively, and the mucking efficiency decreases by 8.8%. The mucking efficiency of the downhill advancement is lower, and the bucket offset angle can effectively improve the mucking efficiency. The mucking efficiency first increases and then decreases with the increase of the cutterhead rotational speed and penetration per revolution, and there are optimal critical values. The research results provide valuable insights for the optimal design of the mucking structure of the TBM cutterhead and the adjustment of the operational parameters of the machine.