Evaluation of the Adaptability of an EPB TBM to Tunnelling through Highly Variable Composite Strata

Table 8

Primary evaluation indexes for the adaptability of an EPB TBM during tunnelling.

Target layer	Adaptability degree of EPB TBM under mixed ground conditions D
Criteria layer	EPB TBM design U1	Tunnelling method U2	Geological conditions U3	Environment conditions U4
Index layer	Total thrust W1; Cutterhead structure W2; Cutterhead torque W3; Cutterhead opening ratio W4; Muck improvement technique W5; Selection and layout of cutters W6; Cutter spacing W7; Muck amount of screw conveyor W8	Advancing speed W9; Rotating speed of cutterhead W10; Earth pressure in cutterhead chamber W11; Shield tail void W12; Wall-back grouting pressure W13	Artificial fill W14; Soft soil stratum W15; Liquefied sand layer W16; Residual soil layer W17; Composite strata W18; Microweathered granite protrusions W19; Hard-rock layer W20; Fault crushed zone W21; Spherical weathered boulders W22	Underground structures W23; Ground buildings W24; Structure of existing tunnel lines W25