## Modelling hard rock jointed pillars using a distinct ...

Deep Mining 2017: Eighth International Conference on Deep and High Stress Mining – J Wesseloo (ed.) ... Zimbabwe P Mushangwe Zimplats, Zimbabwe L Gardner Implats, ... In total, 27 triaxial compressive strength, 17 base friction angle on saw cut fractures (BFA) and 12 direct shear on open joint (SHJO) tests were carried out as part of the ...

## OVERVIEW OF ZIMBABWE’S MINERAL RESOURCE POTENTIAL

• The structure of the mining industry in Zimbabwe is highly skewed • There is a gap between hundreds of small scale mines and a few large mines. • The apparent missing link bridging the two groups simply indicates that there are many small mines with potential to develop into

## Support design and mining practices in bad ground ...

Zimbabwe room and pillar mining ... • Uniaxial compressive strength (UCS) of rock ... 40% of the rock strength (160MPa) was used based on

## In Situ Estimation of Roof Rock Strength using Sonic Logging

equation may be used to help design roof support systems. The paper also addresses the steps that are necessary to ensure that high-quality sonic logs are obtained for use in estimating UCS. 1. Introduction. Uniaxial compressive strength (UCS) is perhaps the material property that is most frequently quoted in rock engineering (Hoek, 1977).

## Confined compressive strength model of rock for drilling ...

Mar 01, 2015 · 1. Introduction. The confined compressive strength (CCS) is one of the most important parameters for drilling optimization, bit selection, and prediction for the rate of penetration (ROP).A large number of ROP models presented in the literature have considered the effect of the rock strength on ROP such as Bourgoyne and Young's model , the roller-cone-bit model presented by Warren , and ...

## Rock mass properties for underground mines

tm is the ‘tensile’ strength of the rock mass. In order to use the Hoek-Brown criterion for estimating the strength and deformability of jointed rock masses, three ‘properties’ of the rock mass have to be estimated. These are 1. the uniaxial compressive strength s ci of the intact rock elements, 2.

## STRENGTH PROPERTIES OF ROCKS AND ROCK MASSES 1 ...

if a rock mass is cut by directional joint sets , the rock mass strength is anisotropic. Rock mass strength is scale dependent and varies with the volume of rock under consideration. The modes of failure of intact rock are multiple. Rock can fail in tension, compression or shear.

## Estimating Rock Mass Strength - BM 1997 02

s = constant depending on the characteristics of the rock mass, σc = uniaxial compressive strength of the intact rock material, σ1 = major principal stress at failure, and σ3 = minor principal stress at failure. The uniaxial compressive strength for the rock mass, σc, rockmass , can be expressed by setting σ3 = 0 in Equation 2.1 thus obtaining

## Dynamic compressive strength of rock salts - ScienceDirect

Jan 01, 2019 · Mining rock salt results in subsurface damage, which may affect the strength because of applied stress, anisotropy, and deformation rate. In this study, we used a Kolsky compression bar to measure the high strain rate response of bedded and domal salt at strain rates up to approximately 50 s −1 in parallel and perpendicular directions to bedding or foliation direction depending on rock salt ...

## ROCK MASS CHARATERISATION: A COMPARISON OF THE

The Southern African Institute of Mining and Metallurgy Surface Mining 2008 G P Dyke Page 219 Rock Block Strength (RBS) Using the Unconfined Compressive Strength (UCS) of the rock mass, an appropriate Intact Rock Strength (IRS) rating value is assigned to the rock mass with the corrected IRS being determined by estimating the percentage of

## USING THE POINT LOAD TEST TO DETERMINE THE UNIAXIAL ...

testing procedure used for the calculation of a rock strength index. This index can be used to estimate other rock strength parameters. The focus of this paper is to present the data analysis used to correlate the point load test index (Is50) with the uniaxial compressive strength (UCS), and to propose

## Rock mass properties for underground mines

tm is the ‘tensile’ strength of the rock mass. In order to use the Hoek-Brown criterion for estimating the strength and deformability of jointed rock masses, three ‘properties’ of the rock mass have to be estimated. These are 1. the uniaxial compressive strength s ci of the intact rock elements, 2.

## Modelling hard rock jointed pillars using a distinct ...

Deep Mining 2017: Eighth International Conference on Deep and High Stress Mining – J Wesseloo (ed.) ... Zimbabwe P Mushangwe Zimplats, Zimbabwe L Gardner Implats, ... In total, 27 triaxial compressive strength, 17 base friction angle on saw cut fractures (BFA) and 12 direct shear on open joint (SHJO) tests were carried out as part of the ...

## Rock mechanics in mining practice (Book) | ETDEWEB

Budavari, S. 1983. "Rock mechanics in mining practice." South Africa. abstractNote = {Chapters cover: fundamental principles of solid mechanics; mechanical properties of rock and rock masses; response of the rock mass to excavations underground; design of mine tunnels and the selection of support; stresses and displacements induced by mining ...

## A review of empirical methods used to estimate rock mass ...

A review of empirical methods used to estimate rock mass compressive strength and deformability in the mining industry E. Villaescusa Western Australian School of Mines, Curtin University of ...

## Lecture 9 – Introduction to Rock Strength David Hart ...

UNIAXIAL COMPRESSIVE STRENGTH C o (x 1000 psi) 0 50 100 150 SPECIMEN LENGTH L (in.) VARIATION OF COMPRESSIVE STRENGTH WITH SIZE C o = 35 x L-0.14 In this plot of the size effect on strength, a power function was used to best-fit the experimental data. NOTE, however, that beyond L=36 in. the size effect ceases to be of much consequence.

## Empirical Estimation of Uniaxial Compressive Strength of ...

Apr 01, 2021 · Empirical relationships for estimating Uniaxial Compressive Strength (UCS) of rock from other rock properties are numerous in literature. This is because the laboratory procedure for determination of UCS from compression tests is cumbersome, time consuming, and often considered expensive, especially for small to medium-sized mining engineering projects. However, these

## ROCK MASS CHARATERISATION: A COMPARISON OF THE

The Southern African Institute of Mining and Metallurgy Surface Mining 2008 G P Dyke Page 219 Rock Block Strength (RBS) Using the Unconfined Compressive Strength (UCS) of the rock mass, an appropriate Intact Rock Strength (IRS) rating value is assigned to the rock mass with the corrected IRS being determined by estimating the percentage of

## the uniaxial compressive strength machine for rocks

Uniaxial compression tests - SP. Specimen inserted in the testing machine between the loading platens with ... Examples of results from an uniaxial compression test including the ... for determining the uniaxial compressive strength and deformability of rock materials.

## 8. STRENGTH OF SOILS AND ROCKS

out for rock. In a direct tensile strength test a cylindrical rock specimen is stressed along its axis by means of a tensile force. The tensile strength is then calculated as the failure tensile force divided by the cross-sectional area. It has been found that a rock core will split along a diameter when loaded on its side in a compression machine.

## Compressive Strength Of Basalt Stone

6.1.7 Compressive Strength. and feldspar and is often used as building stone. Basalt is a common extrusive igneous rock formed by the rapid cooling of basaltic lava exposed at or very near the surface of Earth. These rocks are composed of many distinct minerals. The process of formation of rocks is different for various rocks.

## Correlation Between Point Load Index and Uniaxial ...

Nov 11, 2011 · Uniaxial compressive strength (UCS) is one of the most significant geomechanical properties of rock, being of importance in civil engineering, mining, geotechnical, and infrastructure projects, etc. The UCS is a useful approximate parameter when considering a variety of issues encountered during blasting, excavation, and supporting in ...

## rock strength table mpa - the Punjabian

Rock strength from log parameters - PetroWiki. An understanding of rock strength is important for designing recovery plans for a reservoir and for developing an appropriate reservoir simulation.A detailed discussion of rock failure can be found in Rock failure relationships and Compressive strength of rocks.But the data needed for these methods may not be readily available, so there is a ...

## CHANGE THE UNIAXIAL COMPRESSIVE STRENGTH OF

Keywords: pasta backfill, flotation tailings, uniaxial compressive strength, ore body Borska reka, mass excavation method * Mining and Metallurgy Institute Bor ** This work is the result of the Science Project No. 33021, "Research and Monitoring the Changes in Stress Deformation State in the Rock Mass “IN SITU” around the Underground ...

## Predicting the unconﬁned compressive strength of the ...

Compressive strength is the most widely used design parameter in the construction industry and in rock engineering. For example, Bieniawski [Bieniawski, Z. T., Estimating the strength of rock materials, Is. J. S. Afr. Inst. Min. Metall., 1974, 74, 312– ... International Journal of Rock Mechanics and Mining Sciences 36 (1999) 139–153 0148 ...

## DETERMINATION OF ROCK MATERIAL PROPERTIES TO

Since mining platinum started at Unki Mine in 2005, large and small geologically controlled falls of ground (FOG) have been problematic especially in 2011 where a FOG caused a fatality. This study is about determining the rock properties at Unki Mine and then using the results to design and recommend robust support to reduce

## ROCK MASS CHARATERISATION: A COMPARISON OF THE

The Southern African Institute of Mining and Metallurgy Surface Mining 2008 G P Dyke Page 219 Rock Block Strength (RBS) Using the Unconfined Compressive Strength (UCS) of the rock mass, an appropriate Intact Rock Strength (IRS) rating value is assigned to the rock mass with the corrected IRS being determined by estimating the percentage of

## v116n4a4 Review of support systems used in poor ground ...

The strength of the intact rock that makes up the pillar material, suitably downrated to take into account the scale effect The geometry of the pillar, taking into account the shape and width to height (W:H) ratio. For W:H ratios less than 4.5, the strength of hard rock pillars is given by: Ps = K.W eff 0.5/H0.75 [4] where P s is the pillar ...

## the uniaxial compressive strength machine for rocks

Uniaxial compression tests - SP. Specimen inserted in the testing machine between the loading platens with ... Examples of results from an uniaxial compression test including the ... for determining the uniaxial compressive strength and deformability of rock materials.

## Rock and Ground Support - Normet

The term rock support is the term widely used to describe the procedures and materials used to improve the stability and maintain the load bearing capacity of rock near to the boundaries of an underground excavation. ... compressive and tensile strength within minutes. Ideal for injection into high convergence zones in deep mining or tunnel ...

## Rock Properties.pdf - Engineering Properties of Rocks ...

Unconfined (uniaxial) compression test • The rock sample is unconfined at its side while the load is applied vertically until failure occurs. In this case, the compressive strength is called unconfined compressive strength (uniaxial compressive strength). s c = P / A where P is the failure load, and A is the cross section of the sample

## v118n12a10 A model to calculate blasting costs using hole ...

compressive strength, joint set orientation, the cost of drilling, and the unit cost of explosives. This model will enable engineers to estimate blasting costs prior to designing the blast pattern. Based on the model, an increase in the rock strength and the angle between the bench face and the main joint set will increase the blasting cost.

## Investigation of Rock Mass Properties for Foundation ...

The strength of intact rock may be related to the bearing strength and compressibility of the jointed rocks mass. Added to that, values obtained from splitting test and uniaxial compression test can be used to specify whether the foundation can be excavated using explosive or not, or whether the excavated material can be used as a construction ...

## Modelling Hard Rock Jointed Pillars | SRK Consulting

Modelling Hard Rock Jointed Pillars | SRK Consulting. This paper presents a methodology to design jointed hard rock pillars transacted a clay-filled shear zone at Ngezi mine, Portal 4 (P4), in Zimbabwe. The nature of the problem is highly complex due to the large number of

## Rock mechanics in mining practice (Book) | ETDEWEB

@misc{etde_6842424, title = {Rock mechanics in mining practice} author = {Budavari, S} abstractNote = {Chapters cover: fundamental principles of solid mechanics; mechanical properties of rock and rock masses; response of the rock mass to excavations underground; design of mine tunnels and the selection of support; stresses and displacements induced by mining tabular deposits; design ...

## (PDF) Rock Blasting Technique -Mining Engineering ...

Mining Engineering Department – Faculty of Technology Mineral Universitas Pembangunan Nasional Veteran Yogyakarta February, 2016 Rock Blasting Technique – Mining Engineering Department Lesson 1 Introduction Rock Blasting Technique – Mining Engineering Department Rule of the lesson: 14 x lesson, minimal presence 12 x, the other rules ...

## Selecting A Crusher By Compressive Strength Of The Crushed ...

Selecting A Crusher By Compressive Strength Of The Crushed Rock. Before choosing a crusher for a certain application the quarry and especially the characteristics of the raw material has to be analyzed.Of fundamental significance is the hardness of the material to be crushed.To de-scribe this property the compressive strength, the los angeles index or the mohs hardness should be determined.