Hard rock excavation by roadheaders presents an interesting alternative to mechanical excavation methods or conventional drill and blast excavation. The very low vibration emissions and precise profile of a roadheader excavation may effectively contribute especially to projects with sensible infrastructure in the vicinity. However, the higher susceptibility of this excavation method regarding the rock and rock mass properties does in fact imply a significant risk potential to the application of this method. In order to limit risks connected to insufficient excavation performance and high tool wear rates, the most important rock mass features, such as intact rock strength, rock toughness and rock fracturing must be assessed carefully in the course of preliminary site investigation. Once under operation, additional investigations, like performance documentation, tool wear analysis and rock mechanical field and laboratory investigations may be able to give a better understanding of the development of performance and tool wear as well as consequent operating costs.

1 Introduction

Even if the very low vibration emissions and precise excavation profile of a roadheader may significantly contribute especially to projects with sensible infrastructure in the vicinity, this method is still regarded as rather "exotic" alternative to commonly used methods such as drill & blast or TBM excavation. Reasons for this are usually the significant susceptibility regarding encountered rock and rock mass properties as well as general uncertainties about their application.

An assessment on roadheader application will include estimates on excavation performance and cutting tool wear, both parameters being significantly dependent from rock strength, rock abrasivity and rock mass structure. The presented paper outlines an integrated approach to minimize operational risk by giving easy-to-apply prediction tools and guidelines for preliminary site investigation methods.

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