RELATIONSHIP BETWEEN ROCK FRAGMENT SIZE DISTRIBUTION, EXCAVATED SURFACE ROUGHNESS AND CUTTER FORCES FROM LINEAR ROCK CUTTING MACHINE EXCAVATION

During mechanical rock excavation under a linear rock cutting machine, the fragment morphology and sizes depend on the mode of fracturing, which is also a function of the mechanical properties of the rock and excavation machine parameters. Deeper cutter penetration produces larger fragments than shallower penetration at the same cutter spacing. Thus, there exists a relationship between fragment size distribution and the cutter forces since the cutter forces depend on penetration (spacing/penetration ratio). Also, generating different fragment shapes and size distributions will generate different excavated surface roughnesses. This study, therefore, intends to establish the relationship between fragment size distribution, excavated surface roughness and cutter forces involved in rock excavation using linear rock cutting machine (LRCM). The excavation is executed by linear rock cutting machine mounted with a long-blade disc cutter. The cutter forces are recorded by load cells at a frequency of 5000 samples per second during the excavation. After excavating each pass, the fragments are collected, and size distribution analysis (sieve analysis) conducted. The excavated surface after each pass is imaged using a laser system. These images are used to generate digital elevation models, from which the roughness parameters are obtained. Correlation and regression analysis will be conducted on the results to establish the relationship between the fragment size distribution, surface roughness and cutter forces. The established relationship will serve as a basis for incorporating surface roughness parameters in excavation performance prediction models. This relationship will be used in the prediction of cutter forces which in turn will be used excavation performance prediction.