Research on rock-breaking effect of TBM hob and application of new type cutter

Abstract

TBM hob wear is an important factor that affects the TBM tunneling efficiency and construction cost.Different blade types differ in rock breaking efficiency and wear.By analyzing the rock-breaking mechanism of the arc blade wedged hob, this study established the calculation model of hob normal cutting, and analyzed the influence of hob edge angle on normal cutting force.This study then designed three kinds of hobs with different cutter spacing and three types of hobs with different blade for rock breaking tests in laboratory.Results show that the reasonable cutter spacing is 15mm, sharp blade is prone to be worn, the tooth-like blade, which has higher rock breaking efficiency and wear resistance, is better than arc blade.Combined with the actual situation of the project site, a new hob with wedge-shaped blade is developed, which are applied to inclined shaft TBM tunneling at engineering site.Results show that the wear rate of the new wedge-shaped hob is 20 % less than that of the conventional ones, and the service life of former is longer than that of latter.Under the same geological conditions, new wedge-shaped hob can reduce the number of hobs consumption and improve efficiency of tunnelling.The development and application of the new type successfully solved the problems of hob wear and frequent replacement of hobs in the TBM inclined shaft excavation.It can provide technical support for TBM long distance inclined shaft driving, which not only shortened the construction period, but also saved the construction cost.

Keywords

• rock breaking
• wedge-shaped hob
• hob wear
• inclined shaft tbm tunneling