DEVELOPMENT OF A HARD ROCK EXCAVATOR BY USING AN EDGE EXCAVATION

摘要

As for the construction site such as a tunnel, T.B.M. excavator mounted spirally a lot of discs was used for cutting a hard rock material due to a plane excavation method. However, an edge excavation method was considered to be more effective than the plane excavation method. The aim of this paper is to develop a rock excavator by using of the edge excavation method for hard rock mass. The edge excavation mechanism due to a penetration and rotation speed control system has been verified by several experiments using 2 ripping type disc cutter bits and high strength cement mortar specimen. Here, the penetration speed, radius of curvature at edge, cutting space and unconfined compressive strength of specimen were changed. The individual thrust, rolling resistance and lateral force acting on each ripping type disc cutter bit were measured for the initial edge excavation and steady edge excavation at each step. The difference between the initial and steady cutting stage would be the key point to explain the effective mechanism of edge excavation method. As a result, it was clarified that the rolling resistance was about 1.4 times of the thrust and the lateral force was about 0.8 times of the thrust for the initial edge excavation, and the rolling resistance was about 2.3 times of the thrust and the lateral force was about 0.8 times of the thrust for the steady edge excavation. The individual thrust, rolling resistance and lateral force acting on each ripping type disc cutter bit increased with the increment of penetration speed and radius of curvature at edge.