The post-failure characteristics of rock

Abstract A strain-softening constitutive relationship is introduced that describes the post-failure stress-strain curve for rock regardless of whether the rock is intact or broken. The core of this relationship is an “apparent friction” concept that relates the post-failure apparent cohesive and frictional characteristics of the rock to the strain. The relationship can be determined for a given rock via a series of tri-axial strength tests establishing the peak strength and corresponding strain for a range of confining pressures, together with the determination of the base angle of friction via a simple tilt test. The postulates and assumptions used in deriving this relationship are verified from results of tri-axial tests on both intact and broken rock. This strain-softening relationship is then applied to coal. Having determined the post-failure stress-strain curve for coal specimens, this information can then be used in a finite element program, such as Phase 2, to examine the post-failure characteristics of coal pillars. Using example data, the strength of coal pillars of different width/height ratios are estimated and compared with well-known empirical pillar size-strength relationships. In addition, the post-failure stress-strain behaviour of a coal pillar is compared with an empirical relationship reported in the literature.
Keywords: Failure, Friction, Coal, Rock mechanics, Stress-strain curve.

Full Access to Technical Paper
PDF version for $20.00
Search
Sort By:  Relevance
Showing results 1 - 4
Text
Summary: Aqueous slurries of fine particle size calcium carbonate are used in a diverse range of end-use products. In many cases, the end-use performance is governed by the fineness of the particle size distribution. In turn, the maximum fineness of the particle size distribution is primarily determined by the efficiency of the dispersants used during the production process. Here, we report the sodium polyacrylate mediated dispersion of calcite and kaolin. Firstly, we report a colloid chemical...
Publication: CIM Bulletin
Author(s): J.S. Phipps, D.R. Skuse
Keywords: Calcium carbonate, Calcite, Dispersion, Dispersant, Polyacrylate, Stabilization, Fine particle size.
Issue: 1070
Volume: 96
Year: 2003
Text
Summary: Potassium is one of the three basic plant nutrients along with nitrogen and phosphorus. There is no substitute for potassium compounds in agriculture; they are essential to maintain and expand food production.
Potash is extracted from buried ancient evaporites by underground or solution mining. This accounts for most of the potassium produced. Another important source is brine from land-locked water bodies, such as the Dead Sea, Salar de Atacama or Great Salt Lake. About 95% of potash...
Publication: CIM Bulletin
Author(s): C.F. Perucca
Issue: 1070
Volume: 96
Year: 2003
Text
Summary: Fires due to self-heating of coal have been a real problem since the beginning of mining. In order to minimize the harmful effect of fires caused by spontaneous combustion (sponcom), the tendency of coal for sponcom should be analyzed in detail. This paper presents the results of such research, which had two objectives: firstly, to determine the spontaneous combustion characteristics of lignites of all underground (u/g) mines of Turkish Coal Enterprises (TKÍ) in the laboratory; and secondly,...
Publication: CIM Bulletin
Author(s): T. Guyaguler, C. Karpuz, S. Bagci
Keywords: Spontaneous combustion, Mine fires, Crossing-point temperature, Adiabatic oxidation, Turkish lignites.
Issue: 1070
Volume: 96
Year: 2003
Text
Summary: The St. Lawrence deposit is a large wollastonite skarn (ca. 9 Mt @ 41.3% wollastonite) adjoining the gabbroic-to-syenitic Leo Lake pluton in the granulite facies Frontenac Terrane of the Grenvillian Central Metasedimentary Belt. It occurs within a horseshoe-shaped horizon of quartzite, open to the east. The skarn extends over 1.2 km2, and comprises wollastonite-dominant, wollastonite-clinopyroxene, and diverse quartz-feldspar-sulphide
(-titanite) layers, interbanded with, and strongly folded...
Publication: CIM Bulletin
Author(s): T.A. Grammatikopoulos, A.H. Clark, B. Vasily
Keywords: Skarn, St. Lawrence deposit, Beneficiation, Wollastonite, Industrial minerals.
Issue: 1070
Volume: 96
Year: 2003
Powered by Coveo Enterprise Search