Effects of discontinuities on the rock block geometry of dimension stone quarries: a case study

ABSTRACT

The geometry of rock blocks, including shape and size, is a crucial factor affecting the quarry’s profitability. The block’s dimension is limited by the fracture network properties, especially discontinuity’s orientation, and spacing. Volumetric joint count (Jv), and weighted joint density (WJd) are two well-known indexes to determine the average block’s volume. In this investigation the discontinuity properties of eight quarries are determined through the line and aerial mapping surveys. The investigation was performed along 2258 m scanline in 63 slope benches. Different indexes were used to compare the obtainable rock block’s geometry. An empirical index was proposed considering different aspects of discontinuity network to increase the accuracy of measurements. The index was introduced based on the number of joints in each joint set, average spacing of joints in each joint set, and the total number of joints recorded during the investigation. The joint mean spacing index allows us to estimate the average volume of blocks and evaluate the quarry’s profitability. By increasing the ratio of the joint mean spacing index, the obtainable rock block’s volume and mine profitability increase.

KEYWORDS:

• Discontinuity spacing
• discontinuity orientation
• rock block geometry
• dimension stone
• joint mean spacing index

Acknowledgments

The authors gratefully acknowledge the support of the Kushagaran Novin Pardazesh Company, Iran, and the Mineral Engineering Department of New Mexico Institute of Mining and Technology, USA.

Disclosure statement

No potential conflict of interest was reported by the authors.