Tensile strength in rock mechanics is a characteristic more frequently determined in the indirect rather than direct way. This paper presents a historical review of the development of the indirect method called the Brazilian test,...

Among many factors that influence an excavator’s performance and productivity, the volume of the bucket load and duration of the excavator working cycle are crucial. In this paper, both factors were investigated, including the granulometric composition of the excavated material. The volume of material in the bucket was determined by photogrammetric analysis while the excavator cycle time was measured by analysis of video recordings captured by a digital video camera during the excavator operation. Interconnections between the angle of repose, slewing angle, particle size distribution of material, and their effects on hydraulic excavator productivity were analyzed. It was found that a larger number of fine particles in granular materials with a higher coefficient of uniformity resulted in an increase in the volume of the bucket load. Correlation analysis revealed significant interconnection between the bucket fill factor and swell factor. It was also found that calculation of the production rate according to ISO (International Organization for Standardization) standards was more accurate for materials with a higher angle of repose while the CECE (Committee for European Construction Equipment) standard was more appropriate for materials with lower angles of repose.

Load factors, defined as portion of utilized engine power, are used in estimation of the diesel mining equipment fuel consumption. Every type of equipment is involved in the specific work operation, common in quarrying of crushed stone....

Specific energy is the measure which connects the operating parameters of the machine with the characteristics of the rock in which the machine works and is equal to the total work required to break a unit volume of the rock. It is...

A method based on extensive laboratory and field measurements was developed to determine the dependence of specific rock cutting energy (SEc) on specific drilling energy (SEd) for machines with different operating and design characteristics and similar breaking mechanics. Laboratory measurements were performed on a linear rock cutting device and a laboratory drill, using a measurement system to measure electrical power and cutting forces using force/torque transducers. Field power consumption measurements were performed on a chainsaw cutting machine and a hydraulic rotary drill under real working conditions in the dimension stone quarries. The analysis of the measured results confirmed the strong dependence of the specific rock cutting energy on the specific drilling energy and confirmed that laboratory devices can be used to simulate actual rock cutting and drilling process. In addition, the results are applicable in the dimension stone exploration and exploitation phase in order to assess and reduce energy consumption by optimizing the operating parameters of the chain cutter and/or the hydraulic rotary drill.