Abstract:

A predictive model of thrust force requirements for tunnel boring machines(TBMs) is proposed, which is based on the method of mechanical analysis. When TBM is advancing, there are plenty influence factors including geological conditions, operating status as well as TBM’s structural features. Mechanics characteristics of the interaction between equipment and ground is analyzed. By calculating the limit stress state of rock elements in contact with the arc surface of cutter, a mathematic formula of the force acting on rock by cutterhead is presented, which is able to reflect influences of geological, operating, and structural parameters. Besides cutterhead, thrust components acting on shield and subsequent equipment are also taken into consideration. These three load components make up the total thrust force requirements for TBMs. Then two typical engineering cases in China are involved in model analysis and verification. Furthermore, the total thrust corresponding to unit penetration as an index for the discussion of TBM geological adaptability is introduced. By eliminating the influence of operating parameters, it is proper to analyze the intrinsic correlation between the thrust and geological parameters. It is indicated that uniaxial compressive rock strength(UCS) is the critical factor among various geological parameters. There is an approximately linear relationship between the UCS and the total thrust corresponding to unit penetration. This work can be used not only to estimate the total thrust requirements of TBMs under different geological and operating conditions, but also to provide the reference for equipments’ optimization design and intelligent control.

Key words: geological adaptability, mechanical analysis, TBM, total thrust, predictive model