Assessment methods for excavation performance
This chapter examines methods that have been developed to predict rock excavation by machines. It provides the method which developed in Norway to predict full-face tunnel machine performance. Assessments on the production or performance of tunnel boring machines can best be made using the method of the Norwegian Institute of Technology, which is based on the analysis of a large data base. One of the earliest methods used to assess excavatability by ripping is the seismic velocity of the rock mass as determined in the field by a seismic refraction survey. H. J. Smith considered his rippability rating more appropriate to dredging. Excavation occurs by ripping or cutting. Den Hartog developed a preliminary scheme for the data on production and tool consumption of the rock cutting trenchers, to define the rock properties that determine trencher performance. The results of the application of fuzzy set theory to the trencher project data are promising.