Numerical study on the TBM mucking performance in EH project and optimization of the supporting ribs

To study the cutterhead’s muck transfer performance of the TBM applied in EH project, China, a discrete element method (DEM) based numerical model was built and the mucking process was simulated at different penetration rates and cutterhead rotational speed. It is found that the conventional straight-supporting-rib cutterhead performed well at different penetration rates and low RPMs, but the muck excessive-thrown problem was serious when the RPM was higher than 10 rev/min. To overcome this problem, a new arched-supporting-rib cutterhead was proposed. The curvature radius of the arched supporting ribs is suggested between 1.25 m and 1.75 m, and the offset angle is suggested between 40° and 45°. The newly proposed arched-supporting-rib cutterhead can performed well in muck transfer at a greater RPM range of 4~13 rev/min, which allow the TBM to excavated at low, medium and high RPMs considering ground conditions and requirement of construction progress.