In this study,a detailed analysis is conducted on the shield section project from Luogang station to Shuixi station of the Phase Ⅱ of the Guangzhou metro line 7.The tunneling technology employed by the three-mode tunnel boring machine in full-section hard rock under TBM mode is examined.Furthermore,various aspects,including mucking mode,driving parameter control,cutter management,and stabilizer application,are evaluated.Results reveal the following key points:(1)Using toothed disc cutters in the three-mode tunnel boring machine results in lower cutter consumption compared to smooth disc cutters,accompanied by reduced cutterhead torque.(2)The implementation of mud circulation and double-channel mucking via screw conveyors substantially minimizes mud pipe blockage issues and enhances mucking efficiency.(3)Strategically positioned stabilizers and grippers on the front and middle shields,respectively,ensure shield body stability during boring operations in hard rock strata.(4)Optimal operation parameters for tunneling in full-section hard rock strata include a cutterhead rotation speed of 3.0 r/min,total thrust force of 15 000 kN,thrust speed of 1 300 kN·m,and torque of 8-12 mm/min.
rail transitthree-mode tunnel boring machinehard rock sectiontunneling efficiencyfull-section rock stratum