ABSTRACT
In the recent decades, the earth pressure balanced tunnel boring machine (EPB TBM) is one of the commonly employed mechanized tunnelling methods, which supports the tunnel face with the excavated soil. During excavation, various additives should be injected into the tunnel face, chamber and screw conveyor in order to improve the mechanical and hydrological properties of the muck. In this paper, a lab-scale simulating apparatus for EPB TBM excavation was devised to study the excavation mechanism of EPB TBMs including the additives injection. Subsequently, a series of excavation tests were conducted with different soil conditions, and the experimental data such as the thrust force, blade torque and abrasion loss of the cutter bits were discussed. In this research, the effect of the fine content and water content of in-situ soil and the injection volume of foam (Foam Injection Ratio, FIR) on the mechanical behavior of EPB TBMs were carefully studied in particular.
