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Estimating Some Mechanical Properties Of Rock From In-situ Rebound Values
[A CASE STUDY OF OREKE OPEN PIT QUARRY]
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CHAPTER THREE
3.0 RESEARCH METHODOLOGY (DESK WORK)
The research methodology is the general research strategy that outlines. The way in which research is to be undertaken and among other things, identifies the methods to be used in it. These methods, described in the methodology, define the means or mode of data collection or sometimes, how a specific result is to be calculated. Methodology also is the systematic theoretical analysis of the methods applied to a field of study.
Therefore, the N-type rebound hammer was used to evaluate the hardness of the outcrop at 11 randomly selected points. At each of the sample points, data was collected at an area of 20cm by 20cm according to ASTM (2005). At least 10 measurements were made at each point and any value that differs from the average by more than seven is discarded.
3.1 DETERMINATION OF BULK DENSITY
Bulk density is a basic property of a material and is defined as mass divided by volume while the definition is straight forward, the determination of an accurate and reliable value of a material, bulk density can be difficult to achieve in some circumstance for example, object that consist of irregular shapes that are highly fractured and made up of many pieces can cause difficulties in determining and accurate volume and thus the density.
In most cases, it is not the determination of the mass of the object, but the volume which processes a significant challenges in obtaining an accurate density. Bulk density include both the grain and interstitial spaces.
The bulk density is less than the grain density of the constituent mineral (or mineral assemblage) depending on the porosity.
The bulk density of rock is PB = WG/VB, where WG is the weight of grain (sedimentary rocks) or crystal (igneous and metamorphic rocks) and natural cements. If any, and VB is the total volume of the grains or crystals plus the void (pore) space.
Therefore, density of marble can be calculated by using the equation stated below.
"Density"= Mass/Volume=(g/〖cm〗^3 or kg/m^3)
"Ï = " tÏ/V
Bulk Density=(Density (kg/m^3))/(102kg/m^3 )
Where = Density
tq = Mass of the sample
V = Volume of water level in the cylindrical beaker
3.2 PROCEDURE FOR COLLECTING REBOUND HAMMER VALUE
This basically involved the use of N – type rebound hammer in evaluating the hardness of a marble deposit. The hammer was applied on three different points, at each selected points, ten measurements were made, the average of this measurements was then calculated, any value that has the different of more than seven from the average are to be discarded according to ASTM (2005).
3.3 CONVERTED FROM N – L TYPE DATA
It is therefore not clear why ISRM (1978a) only endorsed the use of the L-type hammer for testing rocks while ASTM (2001) did not specify the hammer types. Ayday and Goktan (1992) have demonstrated that reliable correlation could be developed between the rebound values of the L and N types hammer.
Therefore, Ayday and Goktan 1992 derived an equation to convert N – L type data which is stated below.
Rn (N) = 7.124 + 1.249 Rn (L)
Where Rn (N) is the N type rebound value
Rn (L) is the L type rebound value.
3.4 ESTIMATING UNIAXIAL COMPRESSIVE STRENGTH OF MARBLE (UCS)
The uniaxial compressive strength of rock materials is relatively easy to determine and standardized procedures and available.
This however involves laboratory tests that necessitate careful specimen preparation and rather expensive testing apparatus.
To determine uniaxial compressive strength used by a testing on laboratory or in practical can use the index method in this research, alternatively is to use Schmidt hammer.
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ABSRACT - [ Total Page(s): 1 ]ABSTRACTThe research deals with estimating some mechanical properties of rock from in-situ rebound value in Oreke open pit quarry ,N-Type Schmidt rebound hammer data were collected from Oreke open pit .the data were collected with the view to ascertain the suitability of Schmidt hammer for quick ,cheap and less cumber some estimation of the uniaxial compressive strength of marble .The data collection was strictly carried out by ASTM and suggested equation by different authors. UNIAXIAL COMPRES ... Continue reading---
LIST OF TABLES - [ Total Page(s): 1 ]LIST OF TABLESTABLES 4.1: Determination of Bulk Density for Location 4.2: Density Test Result for Location 4.3: Density Test Result for Location 4.4: Field Rebound Values 4.5: Standard Procedure of Bulk Density Determination 4.6: Standard for Uniaxial Compressive Strength (UCS) ... Continue reading---
LIST OF FIGURES - [ Total Page(s): 1 ]LIST OF FIGURESFIGURES 1: Details of an L type Schmidt hammer 2: Conversion Graph ... Continue reading---
TABLE OF CONTENTS - [ Total Page(s): 1 ]TABLE OF CONTENTSTITLE PAGE CERTIFICATION DEDICATION ACKNOWLEDGEMENT TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES CHAPTER ONE 1.0 INTRODUCTION 1.1 AIM AND OBJECTIVES 1.2 STATEMENT OF THE PROBLEM 1.3 SCOPE OF THE PROJECT 1.4 JUSTIFICATION OF THE PROJECT 1.5 LOCATION OF THE STUDY AREA CHAPTER TWO 2.0 LITERATURE REVIEW 2.1 CONCEPT OF SCHMIDT REBOUND HAMMER 2.2 GEOLOGICAL FORMATION OF MARBLE 2.3 MECHANICAL PROPERTIES OF MARBLE ... Continue reading---
CHAPTER ONE - [ Total Page(s): 1 ]CHAPTER ONE 1.0 INTRODUCTIONRock mechanics engineers design structures built in rock for various purposes, and therefore need to determine the properties and behavior of the rock. The UCS of rocks is one of the important input parameters used in rock engineering projects such as design of underground spaces, rock blasting, drilling, slope stability analysis, excavations and many other civil and mining operations. ISRM (1981) testing of this mechanical property in the laboratory is a si ... Continue reading---
CHAPTER TWO - [ Total Page(s): 3 ]CHAPTER TWO2.0 LITERATURE REVIEW A literature review revealed that most of the empirical equations introduced for determination of the Uniaxial Compressive Strength (UCS) of rocks based on the Schmidt hammer rebound number (N) are not sufficiently reliable mostly due to the relatively low coefficient of correlations. This is attributed to the fact that in most cases one formula is used for all types of rocks, although the density of rocks is introduced to the formulae in some cases. On the ... Continue reading---
CHAPTER FOUR - [ Total Page(s): 7 ]The result obtained for the uniaxial compressive strength range from lowest value to the highest value which is 1.15×1040mpa respectively. Base on the standard present by Deere and Miller (1966) and ASTM (2001). The mean value obtain which is6.22×1040mpa made the marble to be classified as a rock with very low strength. 4.3 DISCUSSION The average rebound value was used trace the UCS with the corresponding bulk density in figure (4.1.1). The result shows that the uniaxial comp ... Continue reading---
CHAPTER FIVE - [ Total Page(s): 1 ]CHAPTER FIVE5.0 CONCLUSION AND RECOMMENDATION5.1 CONCLUSIONThe need to test rock in order to determine their physical and mechanical properties cannot be overemphasized .However , laboratory testing procedures and equipment may be required to do this for engineering project .Hence, the Schmidt rebound hammer (RN) has being used by many researchers to measure the strength and other engineering properties of rocks. This usually enables a quick and easy means of measurement. Marble be ... Continue reading---
REFRENCES - [ Total Page(s): 1 ]REFERENCESAggestalis, G, Alivazators, (2000) Correlating Uniaxial Compressive Strength with Schmidt Hammer Rebound Number, Journal of Bulleting Engineering Geology, Vol. 5,4, ppg 3 – 11.ASTM, (2001) Standard Method for Determination of Rock Hardness of Rebound Hammer Method, ASTM Stand 04.09(D5873-00).ASTM. D-5873(2005) Standard Test Method for Determination of Rock Hardness by Rebound Value Method.Aufmuth, E.R. (2002). A Systematic Determination of Engineering Criteria for Rocks. Journal ... Continue reading---
