rock mechanic lab

8/2/2019 Rock Mechanic Lab

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Baluchistan University of Information Technology,

Engineering and Management Sciences Quetta

Lab report: Rock Mechanics

Submitted to: Mining Engineering Department of UET Lahore

Prepared by: Students of Mining Engineering Department BUITEMS Quetta

Group # 4

No Names CMS

(1) Nouman Rahim 5714

(2) Saqib Ajmair 5749

(3) Khushal Zeb 5703

(4) Fazal ullah 4444

(5) Ijaz-ul-haq 10559

(6) Kausar Sultan shah 8911

(7) Naeem Abas 9671

(8) M.Ejaz rasheed 10837

BUITEMS Quality & Excellence in Education


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Acknowledgment

We are very grateful to UET Lahore for giving us the chance of performing practical lab work in such a

friendly and learning environment. We would like to pay thanks to Engr. -------- and our organizer Engr.--

------------- for their help and cooperation throughout the week.

We would also like to thanks Engr.--------------, Engr. -------------, Engr. ----------------- and Engr.-----------------

- for giving us the great learning time and helping us in performing practical work at UET Lahore.

We are very grateful and thankful from core of our hearts to all of them for so supporting and helpful to

us with so polite and friendly attitude.


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Preface

In order to be competitive in the world of engineering, in order to get

strong grip on theoretical knowledge, An Engineer should have practical

exposure. Theoretical knowledge and practical experience are two

different modes of knowledge. In order to see practical implementation

of theoretical knowledge in laboratories is the best place. Performing

practical work in disciplined organization like UET Lahore is a grate

honor for us. UET is one of the most modern university in Pakistan

which labs. Are, equipped with latest machinery. During at UET we gain

a lot of knowledge about practical engineering work. We tried our best

to gain as much knowledge as we can in a week. The way UET treated us

is more than appreciation.


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List of experiments

Experiment #01

Preparation of test specimen (core drilling, cutting and lapping)

Experiment#02

Determination of the point load index: Is (50).

Experiment#03

Determination of elastic constants (Es, Vs)

Experiment#04

Determination of Schmidt Rebound Number

Experiment#05

Determination of Tensile Strength of a given rock sample.

Experiment#06

Determination of Uniaxial Compressive Strength (UCS) of a given rock sample.

Experiment#07

Determination of Slake Durability index of a given rock sample.

Experiment#08

Determination of Porosity, Density of a given sample

Experiment#09

Determination of Sonic wave velocity through the rock sample


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Experiment#01

Preparation of test specimen (core drilling, cutting and lapping)

Scope:

In preparation of test specimen we required standard/specific sample for

valid result.

Selection of sample:

The sample which is collected from main position, represent the

composition of rocks of that area. The sample must be in pure form.

The samples which we used for performing are:

1. Lime stone

2. Stand stone

3. Dolomite

The size of sample should be from 1 inch to 6 inch.

(1)core drilling:

It is done by the core drilling machine. Coring depend upon the

speed of machine and on the types of bed formations. The sample which

we collected through drilling machine is lime stone.


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(2)Core cutting:

In core cutting we cut the core according as required length,

the cut should be square instead of inclined cut, this is done by cutter

blade.


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(3)Lapping / grinding:

In lapping we make smooth surface of core then check the

irregularities on the core sample. Which is removed by lapping

machine or we make it by special sand.


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Experiment#02

Determination of the point load index: Is (50).

Scope:

Its purpose is to measure strength of rocks by applying a concentrated load,

or by applying point load.

Apparatus:

Point load index machine

The apparatus should be coherent. The accuracy range should be +_

0.7mm.

There are two types of loading;

1. Diametric loading

2. Axial loading

The test which we performed is diametric loading. The apparatus shouldbe,

(1)Rigid

(2)Coherent

(3) Instrument attached for measuring length.

Procedure:

Place the sample in between

Measure the diameter from the scale shown on the point load testing

machine.

Start the process of applying force on the sample

.


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Formules:

D= distance b/w platens

Then L/D= 1.4

FOR AXIL LOADING:

L/D=1.1+-0.5

Calculation:

Is (index) = P/D2

3.95/ (42mm)2

=0.00223

UCS=24 Is (50)

F=correction factor

F= (D/50)0.45


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In Diametrical shape


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Experiment#03

Determination of elastic constants (Es, Vs)

Scope of the experiment:

It is used to measure the tensile strength of rock sample. It is indirect method for finding the

tensile strength. Compressive strength is applied to the rock specimen and breaks it into two

parts in tension. It is easy to conduct. It is found by any compressive machine.

For direct values individual machine for finding tensile strength. Diametric load is applied on

rock samples.

Apparatus:

Any compressive load machine and the grade to find the values of loads, varnier calipers and

tape.

Related theory=

Tensile strength is the ability of a body to bear tensile force is called Tensile Strength. The body

break

in tension of the compressive stress less than 3 times than tensile stress. When compressive

stress is applied then tension is produced at the edges which break the body. It is preferred in a

rock disc of specified dimension.

Type of rock: Disc of lime stone.

Dimension of disk:

The surface of disc should be flat.

The diameter(D) of disc should not less than NX size (54mm)

The thickness (t) will be t/D=0.5

t=D 0.5

Range of thickness= (0.2-0.75)


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Measurements:

If Tb be the tensile strength then Tb=2 P/Pie*Dt

Where Tb= Tensile strength

P=Breaking load

D= Diameter

t= Thickness

Calculations:

P=3480kgf

=3840*9.81N

=34138.8N

Tb=2P/pie*D t

=2*34138.6/3.143*42.7*28.83

=17.68

For thickness of disc:

S. No Thickness (t) Thickness (mm) Avg. thickness

1 T1 28.80

28.83

2 T2 28.85

3 T3 28.80

4 T4 28.85


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For diameter of disc:

S. No Diameter(D) Diameter (mm) Avg. diameter

1 d1 42.7

42.7

2 d2 42.7

Recommendation:

Diameter should not less the normal size.

Smooth surface and should be well prepared. Thickness of sample should be 0.5 time of the diameter

and gradually increasing the load with constant increasing. Break rate should be uniform and will

perform in 20 second.


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Photo during experiment performance

Experiment #04

Determination of porosity and density of a given rock sample

Scope of the experiment:


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Porosity is a measure of the void (i.e., "empty") spaces in a material, and is a fraction of the

volume of voids over the total volume, between 01, or as apercentagebetween 0100percent.

The term is used in multiple fields

including pharmaceutics, ceramics, metallurgy, materials, manufacturing, earth

sciences and construction.

Specific gravity is the ratio of the density (mass of a unit volume) of a substance to the density

(mass of the same unit volume) of a reference substance.

Density The mass density or density of a material is defined as its mass per unit volume.

Apparatus:

Varnier calipers, balances, oven (105 centigrade -24hr), vacuumed desiccators

Procedure:

Rock should be intake and well prepared. First find the length and diameter of the core. For one

hour it is kept in water after that is weighted we will get the wet weight of the sample. Then

place it in oven at 105celcious up to 24hr.after that it is weighted and we will get the dry weight

of the sample.

Weight of dry sample=

Volume=mass/density

Volume of water=Vw=mw/dwR=D/2=51.96/2=25.98

Now Vt =pie*r2*l

=3.14*(25.98)2*73.975

=80483.293

Density of wet sample = dw= Wwet/Vt

=377g

Density of dry sample = Wwet =

=368.5g

Vw= (W wet W dry)/ dw

Vw= (377-368.5)/0.00468
http://en.wikipedia.org/wiki/Percentagehttp://en.wikipedia.org/wiki/Percentagehttp://en.wikipedia.org/wiki/Percentagehttp://en.wikipedia.org/wiki/Pharmaceuticshttp://en.wikipedia.org/wiki/Ceramicshttp://en.wikipedia.org/wiki/Metallurgyhttp://en.wikipedia.org/wiki/Materialshttp://en.wikipedia.org/wiki/Manufacturinghttp://en.wikipedia.org/wiki/Earth_scienceshttp://en.wikipedia.org/wiki/Earth_scienceshttp://en.wikipedia.org/wiki/Constructionhttp://en.wikipedia.org/wiki/Densityhttp://en.wikipedia.org/wiki/Masshttp://en.wikipedia.org/wiki/Volumehttp://en.wikipedia.org/wiki/Volumehttp://en.wikipedia.org/wiki/Masshttp://en.wikipedia.org/wiki/Densityhttp://en.wikipedia.org/wiki/Constructionhttp://en.wikipedia.org/wiki/Earth_scienceshttp://en.wikipedia.org/wiki/Earth_scienceshttp://en.wikipedia.org/wiki/Manufacturinghttp://en.wikipedia.org/wiki/Materialshttp://en.wikipedia.org/wiki/Metallurgyhttp://en.wikipedia.org/wiki/Ceramicshttp://en.wikipedia.org/wiki/Pharmaceuticshttp://en.wikipedia.org/wiki/Percentage


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=1816.2313

Water content in percentage:

(Water content in wet sample water content in dry sample)*100/Water content

in dry sample

Water content= (377-368.5)/368.5*100

= 2.30665

Volume of water will be the volume of porosity

n = Vw/Vt

=1816.239/80483.292

=0.0225

Specific gravity= rho dry / rho W (1-n)

S.no Length of specimen (L) Diameter of specimen(d) Thickness of specimen(t)

1 75 52.25 28.80

2 74.15 51.80 28.85

3 72.25 51.85 28.80

4 73.70 * 28.85

5 74.10 * *


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6 74.65 * *

* Avg=73.975 Avg=51.96 Avg=28.825


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Experiment #05

Determination of slake durability Index

Scope of the experiments:

To study the weathering effects on rock sample.

Weathering is a process of breaking up rock materials under the influence of

air and water. It designs the Earth's surface by shaping it through different

physical and chemical processes. Each of these processes has a different

effect on rocks and their minerals, and different rocks react differently to

weathering, depending on their structure. The three types of weathering

processes are mechanical (or physical), chemical and biological weathering

Apparatus:

Electric motor (20rpm) and the sample is magmatite.

Precaution:

No perforation should be closed due to particles of samples. The

perforated drum will be submersed in water up to 20cm.The weight of

rock sample from 45g

50g.The 10 pieces of rock sample be prepared

having a diameter of 2inches.The sample should not be sharpen edges.

The edges should be making round.

The size of rock sample should not greater then 3mm.

Procedure:

The perforated drums should be clean from particles of rock samples

and weighted the empty drum then putt the dry rock samples and again

weighted. After that submerged into water up to 20cm. Start the

electric motor with speed of 20 rpm up to 10 minutes. Then weighted

the drum contain the wet samples of rock. After that again weighted the

wet drum without the rock samples. Place the wet sample in oven up to

106celcious till 24 hr.


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A= initial mass of drum + rock pieces

B= massafter first rotation

C= mass after 2nd rotation

D=mass of dry & clean empty drum

FORMULA:

Durability index=

Mass retain after the cycle/initial mass of rock sample

Id1 = [(B-D)/ (A-D)]*100

In our experiment

A=250+250.2+D

B=252+251.5+D

C=249+250.5+D

D=2kg=2000g

A=250+252+2000=2502B=252+251.5+2000=2503.5

C=249.5+250.5+2000=24099.5

D=2000g

For Id1 = [(B-D)/ (A-D)]*100

Id1= (2503-2000) / (2502-2000)*100=100.192

For Id2= [(C-D)/ (A-D)]*100

Id2= (2499.5-2000)/ (2502-2000)*100=99.5


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Apparatus of experiment


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Experiment # 06

Determination of UCS by Schmidt Hammer Rebound Number.

Related theory:

UCS means uniaxial compressive strength which can be finding by direct method

and by an indirect method.

Direct method: it is an expensive method and time consuming, also a lot of

preparation needs i.e. coring, sampling etc.

Indirect method: it is easy and better then directs method because it does not

need the core preparation or sampling. It is not expensive, no need of a lot of

time consuming but not to accurate.

Working principle:

Weight of hammer and the force which will be applied should be constant. It

mechanism is spring loaded and energy is stored when it reached to constant

point then it is released and then transfer to the rock mass, after that it will

rebound to hammer where the value is noted.

At different orientation the hammer will give different values due to gravitational

effects.

There are three types of hammer

1. L-Type

2. M-Type

3. N-Type

But here we used the L-Type Hammer.


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Observation and calculation:

C.F= specified standard value/ Avg of 10 reading

On different location noted the rebound nor.

Average the number

And then plotted the values on chart

Noted: In this experiment we used three different surfaces

Core

Floor

Steel base

S.no 1 2 3 4 5 6 7 8 9 10

Core 15 19 16 16 23 24 20 20 22 17

Floor 13 29 28 31 36 24 * * * *

Steel base 32 33 36 37 36 36 38 39 28 *


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Experiment # 07

To determine UCS of given rock sample.

Scope:

This is test is intended to measure the UCS of rock sample of regular

geometry. It is used for classification and characterization of intact rock.

Related theory:

Compressive strength is the capacity of amaterialor structure to withstand

axially directed pushing forces. When the limit of compressive strength is

reached, materials are crushed.

When a specimen of material is loaded in such a way that it extends it is said to be

in tension. On the other hand if the materialcompressesand shortens it is said to

be in compression.

On an atomic level, the molecules oratomsare forced apart when in tension

whereas in compression they are forced together. Since atoms in solids always try

to find an equilibrium position, and distance between other atoms, forces arise

throughout the entire material which oppose either tension or compression.

The phenomena prevailing on an atomic level are therefore similar. On a

macroscopic scale, these aspects are also reflected in the fact that the properties

of most common materials in tension and compression are quite similar.

Apparatus:

UTM, varnier caliper, prepared rock sample

Procedure:

The range of length to diameter ratio (L/D) should be 2.5-3.0, not greater than 3.

Diameter should be the normal size of core which is 54mm.the specimen should

be flat and edges should be sharp rock specimen is placed in UTM then applyingthe load by compressing the sample.
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Observation and calculation:

Rock

Sample

Avg diameter

(cm)

Avg length

(cm)

Specimen

area(m2)

Breaking

load(kg)

Breaking

load(Nm)

UCS (Mpa)

Dolerite

D1=4.74

D2=4.71

D3=4.72

L1=13.775

L2=13.735

L3=13.760 A=0.001752 20200 198162 113.1

Avg=4.725 Avg=13.75


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Experiment#09

Determination ofsonic waves velocity for a given sample rock core

Related theory:

Sonic wave:

Sound waves are called sonic waves, which moves faster in solid than

gases. The velocity of sound waves is directly proportional to the

compression and compression is proportional to the strength.

Procedure:

We take different samples of rocks and first find their length which is

distance, measured by varnier calipers and then find the velocity.

For primary wave velocity

Vp= d/tp

Tp= primary wave time

For secondaryVs=d/ts

Sample

no.

Length (cm) Time

(sec)

Velocity Vp=d/tp

Lime

stone

L1=11.16

L2=11.15

L3=11.15

T1=18.6

T2=18.7

T3=18.5

1.667

Avg=11.153 Avg=18.6

Sand

L1=9.215

L2=9.100

L3=9.120

T1=18.4

T2=18.6

T3=18.5

2.020


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stone Avg=9.145 Avg=18.5

Dolerite

L1=13.885

L2=13.890

L3=13.865

T1=19.0

T2=19.5

T3=19.5

0.719

Avg=13.880 Avg=19.3


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Mine ventilation

List of experiments:

Experiment# 01


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Determination of inlet by using Traversing pitot tube

Experiment#02

To measure the velocity of air by using vane anenometer

Experiment#03

Calibration of anenometer

Experiment#04

To measure the relative humidity of air using sling psychomotor.

Experiment#5

Determination of the effect of miss alignment of pitot static tube an air

stream (velocity pressure variation with an angle of yaw)

Experiment#06

To determine the effect of miss alignment of a pitot static tube an air

stream (static pressure variation with an angle of yaw).

Experiment#07

Experiment#01

To determine the inlet by using the traversing pitot static tube

Applications


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It is used to determine the direction of air.

It is used to measure a velocity.

The accuracy should be + minus 1.

EQUIPMENT:

1. Mine ventilation educators

2. Manometer

Related Theory:

Experiment # 2


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Objective:

To measure velocity of air by using vane anenometer .

Apparatus:

The apparatus is vane anemometer. It consists of a dial

which gives distance. It has 3-scale, the total distance of the first one

is 100ft, second one is 1000ft and the third one is 10000ft. and

stopwatch which to calcoate the specific time for measuring the

velocity of air.

S.NO START TIME

(Sec)

END TIME

(SEC)

DISTANCE

(ft)

VELOCITY

V=d/t

m/sec

1 0 48.4400

5.847

2 0 70 455 6.5

rock mechanic lab

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