Rock Testing Guide

167

Rock mechanicsRock sampling and sample preparation . . . . . . . . . . . . . . . . 168Strength and deformability tests . . . . . . . . . . . . . . . . . . . . . . 171Automatic tests systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172Elastic modulus and strength characteristics of rock specimens in uniaxial and triaxial conditions . . . . . 173Hoek cells for triaxial tests . . . . . . . . . . . . . . . . . . . . . . . . . . 175Semi-automatic test systems . . . . . . . . . . . . . . . . . . . . . . . . 178Classification tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180Splitting tensile test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180Slake durability index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180Permeability of rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181Behaviour of joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182Measurement of shear strength . . . . . . . . . . . . . . . . . . . . . . 183Roughness measurement . Profilometers . . . . . . . . . . . . . . . . 183Tilt test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183Strength index (point load) . . . . . . . . . . . . . . . . . . . . . . . . . . 184Rock classification hammer . . . . . . . . . . . . . . . . . . . . . . . . . . 184

45

I N T R O D U C T I O N

According to the “Committee on Rock Mechanics, National Academy of Sciences”, rock mechanics is a theoretical and applied science concerning the physical behaviour of rocks subjected to stress conditions of different origin . In general terms, rock mechanics involves the study of underground works such as tunnels, and surface construction such as open quarries or dam foundations .

When a rock sample is subjected to defined stress conditions in the laboratory, the stress-strain diagram can show behaviours of non linearity also for very small strains, hysteresis, anisotropy, fluage conditions, etc . All these phe-nomena can be mathematically described .

Rock Testing

Contents

Testing equipment for the construction industry

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168

Accessories for 45-D0536 core trimmer and cut-off machine

s45-D0536/1 Cooling recirculating pump complete with reservoir. 230 V, 50 Hz, 1 ph.

s45-D0536/1Z Same as above but 110 V, 60 Hz, 1 ph.

s45-D0536/1YSame as above but 220 V, 60 Hz, 1 ph.

s45-D0536/2 Diamond cutting blade. 230 mm dia. x 2.5 mm thickness. Maximum cutting area 110x70 mm

s45-D0536/3 Double-faced diamond cup wheel. 205 mm dia. x 16 mm thickness. Used for finishing sample ends parallel and at right angles to the axis

s45-D0536/4Clamping device for irregular pieces max. dim. 57x104x102 mm (length) and core from 15 to 60 mm dia.

45-D0529 Detail of 45-D0536 with double-faced cup wheel 45-D0536/3 during surface grinding of cylindrical specimens ends

Detail of 45-D0536 with cutting blade 45-D0536/2 during operation

45-D0536/3, D0536/2

Used for preliminary rock identification.

M 45-D1710 Rock pick pointed tipFully polished, leather grip.

A Weight approx.: 650 g

M 45-D1711

Rock pick chisel edgeFully polished, nylon vinyl grip.

A Weight approx.: 550 g

M 45-D0529

Mohs hardness scale set

M 45-D0536

Laboratory core trimmer and cut-off machine, complete with water inlet. 230 V, 50 Hz, 1 ph.

M 45-D0536/ZSame as above but 110 V, 60 Hz, 1 ph.

M 45-D0536/YSame as above but 220 V, 60 Hz, 1 ph.

q STANDARDASTM D4543

General description and specifications

Used to obtain rock samples perfectly machined (cubes, prisms, etc.) from irre-gular rock or core pieces. It is supplied complete with a proper vice to hold irre-gular pieces firmly in place up to 70x140 mm approx. Another “V” vice is used to cut cores to a maximum size 75 mm dia. x 140 mm height. Longer cores can be obtained by turning the samples upside down in the vice. It is supplied complete with cooling water inlet. Blade cup wheel and water pump must be ordered separately.

Power: 1100 W

Speed of the blade: 3000 r.p.m.

BDimensions: 730x1050x590 mm

A Weight approx.: 100 kg

- Usable for both trimming and surfa-ce grinding

- Usable to obtain cube specimens from irregular pieces

- Transparent protec-tion cover confor-ming to CE directive

45-D0536 with 45-D0536/4

45-D1710, 45-D1711

Rock picks Core trimmer and Cut-off maChine

ROCK TESTING

Rock sampling/ Sample preparation . . . . . . . . . . . . . . . .


Rock picks/ Core Trimmer

45

169

Accessories

s45-C0331 Clamping device for cores max. dia. 100 mm complete with transparent protection

s45-C0343 to 45-C0346 Drill bits and spigot adaptors

Accessories

s45-C0211/4 Diamond blade 350 mm dia. for rock specimens

s45-D1717 Clear safety goggles

M 45-C0210/C

Rock and masonry saw. 380 V, 50 Hz, 3 ph.

M 45-C0210/CZ

Same as above but 220 V, 60 Hz, 3 ph.


This rock and masonry saw has been spe-cially developed to cut rock or core sam-ples. The machine is supplied complete with a special clamp to allow irregular specimens to be held firmly in place during the cutting operation. The machine can accept blades up to 450 mm dia. Supplied complete with base frame, water pump and “V” shaped cylinder clamp. The blade must be ordered separately (see accessories).Cutting depth (mm): 115 mm with 350 mm dia. cutting blade and 165 mm dia. with 450 mm dia cutting blade.

Power: 2250 W

BDimensions: with base 1200x800x1400 mm


45-C0210/C with 45-C0211/4

M 45-C0330

Laboratory coring machine, 2-speed, complete with water inlet. 230 V, 50-60 Hz, 1 ph.

M 45-C0330/Z

Same as above but 110 V, 60 Hz, 1 ph.


This machine is specifically used in the laboratory for cutting core samples from hard material such as rock and concrete. A clamp is provided to firmly secure the material during the cutting cycle. A special tool is also available (see accessories) to prepare rock samples from core pieces. Drile bits not included. See accessories.

Power unit: 1800 W

Coring speed: 1485/2720 r.p.m.

Coring range: dia. 8 – 60 mm

BDimensions of the base tray assembly: 450x450x300 mm approx.


sCode D.C.D.M.A. Ø specimen mm inches 45-C0343 AX 30.10 1.18545-C0344 1.5 in. 38.10 1.50045-C0345 BX 42.04 1.65545-C0346 NX 54.74 2.155

Models of core drill bits

45-C0330 with core bit taking sample

from a large stone

45-C0330 with core bit taking

sample from a large rock core

Transparent acrylic protection

45-C0331

Cutting saws Coring maChines and bits

ROCK TESTING

. . . . . . . . . . . . . . . . Rock sampling/ Sample preparation


Cutting saws/ Coring machines

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170

Accessories and spare parts

s82-D1250 Dial gauge 5x0.001 mm

Accessories and Spare parts

s55-C0201/B1 Spare Set of 10 abra-sive sectors

s55-C0201/B2 Spare Set of 10 dia-mond impregnated sectors

s55-C0201/B3 Accessory to connect an aspirator for dry grinding procedure. Aspiration not included

s55-C0201/B4 Clamping device for cylinders from 100 to 160 mm dia.

s55-C0201/B5 Clamping device for cylinders from 50 to 100 mm dia.

q STANDARD EN 12390-2, ASTM D4543

M 55-C0201/B Specimen grinding machine. 220-380 V, 50 Hz, 3 ph.

M 55-C0201/BZ Same as above but 220 V, 60 Hz, 3 ph.


Used to grind and polish concrete speci-mens, natural stones, ceramic materials, rock samples etc.The cube cylinder and core specimens can be easily locked on the table and the grinding head 330 mm dia. can be radially moved either manually or automatically in both directions so the only manual operation requested is the lowering of the grinding head by the top hand wheel. The machine is supplied complete with chip guard, coolant tank, motor pump, one set of abrasive sectors and instruction manual. Diamond grinding sectors are available on request (see accessories). The machine is supplied complete with clamping element for 100, 150 and 200 mm cubes. Clamping devices for cylinders are also available on request (see accessories).The 45-D0534/B Core face preparation jig can be easily fitted by the clamping ele-ment supplied with the machine.

General specificationsTable dimensions: 775x280 mm

Grinding wheel dia.: 330 mm

Max. vertical daylight: 350 mm

Min. vertical daylight: 145 mm

Max. specimen size: 200x200 mm cubes;

dia. 160x320 mm cylinders

Grinding wheel speed: 1400 r.p.m

Automatic cross feed in both directionsSafety guard with door locking switchGrinding spindle motor power: 1,900 W

Feed motor: 110 W

Pulp motor: 100 W

Total power: 2200 W

B Overall dimension: 1200x1020x1640

mm (lxvxh)


A Weight approx. with packing: 415 kg

55-C0201/B

q STANDARDASTM D4543, ISRM Sugg. Method

M 45-D0539

Rock sample verification apparatus


Used to verify the dimensional and shape tolerances of rock core specimens up to 50 mm dia. by 100 mm length. The straightness of the cylindrical surface can be easily verified by the top dial gauge as well as flatness and verticality of end surfaces by the same dial gauge fitted to the lateral magnetic articula-ted dial gauge holder.The apparatus comprises a base support with column and dial gauge holder that can be adjusted precisely vertically, a precision dial gauge 5x0.001 mm, a “V” block, a magnetic articulated dial gauge holder and small circu-lar magnets to fit the “V” block on the base.

Support base dimensions: 135x170x250 mm

Column height : 200 mm

“V” block dimensions: 45x45x100 mm

Dial gauge: 5x0.001 mm


M 45-D0534/B

Core face preparation jig


For preparation of parallel and flat core faces using horizontal surface grinders (e.g. 55-C0201/B). Consisting of a 4 place locking device capable of clamping core samples from 20 to 55 mm dia. It can be mounted on most grinding machines with or without magnetic chuck.


45-D0539 with a supplementary 82-D1250 gauge


ROCK TESTING

Sample preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Specimen grinding Specimen dimenSional verification

Speciment grinding/ Dimensional Verification

45-D0534/B

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171

Strength and deformability tests

Most of the information obtained from laboratory tests are sub-stantially related to the stress and strain characteristics of the tested materials .The tests generally performed on cylindrical rock samples are the following:- Evaluation of the compressive

strength and strain in uniaxial conditions

- Evaluation of the compressive strength and strain in triaxial conditions .

q STANDARDASTM D3148, D2938 ISRM: Suggested methods for determining the uniaxial compressive strength and defor-mability of rock materials

The uniaxial test is performed applying an increasing load at a constant rate of stress between 0.5 and 1.0 MPa/s. Axial and radial strain are measured with high sensitivity (about 5x10-6). Subsequent load-unload cycles are also carried out to obtain a correct evaluation of the compressibility properties.

q STANDARDASTM D2664, D5407ISRM: Suggested methods for determining the strength of rock materials in triaxial compression

The triaxial test is performed on test rock samples, contained in a rubber sealing membrane, placed within a triaxial cham-ber and subjected to an isotropic pressure (generally between 5 and 60 MPa), kept constant during the test. An axial load is subsequently applied; tests and measure-ments are carried on in the same way as for uniaxial tests.

Triaxial test on rock materials with measurement of axial strainsTypical Peak Strength Envelope (diagram σ1 νs. σ3)

Triaxial test on rock materials with measurement of axial strainsTypical Failure Envelope (diagram τ νs. σ)

From the measurements recorded during the test the following information is obtai-ned:

- Rate of stress versus axial and radial strain- Maximum or failure stress- Tangent and secant Young’s modulus mea-

sured on the stress-axial strain curve- Rate of radial strain versus axial strain to

obtain the Poisson’s ratio- Maximum stress versus applied cell pressu-

re (in the triaxial tests) to define the failure envelope and the corresponding properties (cohesion and friction).

Another important parameter investigated in the triaxial tests concerns the perme-ability characteristics of rocks and rock behaviour when subjected to high water pressure, especially for the study of dam foundations, and generally for under-ground tunnels and cavities.


ROCK TESTING

. . . . . . . . . . . . . . . . . . . Strength and deformability tests

Uniaxial test Triaxial TesT

Uniaxial and triaxial test

45

172

and strength characteristics of rock specimens in uniaxial and triaxial conditions

q STANDARDASTM D2664, D2938, D3148, D5407, ISRM Sugg. Method EN 14580, EN 1926

IntroductionControls rock mechanics automatic test systems are designed to test various mate-rials from soft sandstone to high strength basaltic samples. The complete test system includes: - Servohydraulic control console for

load application conforming the relevant standards (see ADVANTEST code

50-C9842)- High stiffness testing frame to be

selected conforming to the size of the sample and the expected strength (see load frames from 50-C4600/FR to 50-C6600/FR model page 238)

- Servohydraulic control console for lateral pressure control (see SERCOMP 7 code 45-C7022/S). This unit which is deri-ved from the standard SERCOMP 7 code 50-C7022, has been specifically designed for rock testing (Triaxial tests only)

- Hoek triaxial cell to be selected confor-ming the specimen size (Triaxial tests only)

- Strain gauges and accessories- Test software.

Operating principle

According to the reference standards, during the test the compression load on the rock specimen shall be applied conti-nuously without shock, in such a manner to produce a strain rate as constant as possible, so that failure will occur within 5-10 min of loading or alternatively at a constant rate of stress, within the limits of 0.5-1.0 MPa/sec. Moreover, for triaxial tests, the confining pressure has to be maintained constant to within ± 1%. Our new System has been designed to com-pletely fulfil these strict specifications of the test procedures. The ADVANTEST 9 is driven by a sophisticated micro-processed servo-control and both uniaxial and tria-xial tests can be carried on at very stable rate of stress, displacement or strain. The SERCOMP 7 provides the automatic control and managing of cell pressure within the limits prescribed by the Standards. Strain measurements are performed by means of strain gauges applied directly to the spe-cimen, both in axial and radial direction,

so that Poisson’s ratio and compressibility parameters are easily and properly evalua-ted during the test.Axial load and cell pressure are also moni-tored by means of load cells and/or pressu-re transducers at high levels of sensitivity and accuracy.All the test data are graphically displayed in real time, and stored in ASCII files for further analysis with appropriate software packages.

Note. For a complete list of suggested items to perform Triaxial and Uniaxial test see Table on page 177.

50-C5902/FR Frame with Hoek cell, 50-C9842 ADVANTEST 9, 45-C7022/S SERCOMP 7, and 86-D2999 PC cabinet

Main features of the complete system

- Automatic Uniaxial and Triaxial compression tests

- P.I.D. closed loop control- Control up to 4 different

hydraulic frames- Tests performed under control of: - Load/Stress - Displacement - Strain- Easy access to graphical and

numerical monitoring in real time of all the measurements: axial load and displacement, cell pressure, axial and hori-zontal strain

- Automatic control of cell pressure for triaxial tests- Particularly suitable for investigation of the past failure behaviour of rocks

(displacement controlled tests)- Real time variation of the settings, including the control

method (load, displacement or strain)

ROCK TESTING

Automatic test systems . . . . . . . . . . . . . . . . . . . . . . . . . . . .


Determination of elastic moDulus

45

173

Sercomp 7 Advantest 9 45-C7022/S 50-C9842

Hydraulic port 2* 4* Power W 750 750Max. working pressure, bar 600 700Test performance with PID closed loop control with PID closed loop controlResolution up to 1/65000 up to 1/262000Current specs. 230 V, 50-60 Hz, 1 ph. 230 V, 50-60 Hz, 1 ph. or 110 V, 60 Hz, 1 ph. or 110 V, 60 Hz, 1 ph. (please specify) (please specify)Overall specs. mm (lxdxh) 470x410x1000 470x410x1000 + PCWeight approx. kg 120 140 (including PC and printer, which are supplied with the unit)

AdvAntest 9:an advanced flexible testing system ideal for standard and advanced automatic tests on construction materials

• P.I.D.Closedloopcontrol• Controlupto4differenthydraulic

frames• Performtestsundercontrolof: - Load/Stress - Displacement - Strain• Forconnectionofpressuretransducer,

load cells, displacement and strain transducers

• ParticularlysuitabletotestDeformability and Ductility (from post-peak test path) of:

- Rock samples - Fiber reinforced concrete - Shotcrete - Concrete with polymer fibre lining • Highflexibility:cancontrolverylow

capacity hydraulic frames up to 5000 kN

• Advanced Quality-Performance/Price ratio.

The system is fully described on page 247

Trixial test on rock core with measurement of vertical stress, axial and circumferential strain and confining pressure.

Detail of rock sample fitted with strain gages

General specifications of the SERCOMP 7 and ADVANTEST 9 consoles(For more details and specifications see pages 241 and 247)

ROCK TESTING

. . . . . . . . . . . . . . . . . . . . . . . . . . . .Automatic test systemsDetermination of Elastic Modulus and strength characteristics of rock specimens in uniaxial and triaxial conditions (continued)


N O T E *The SERCOMP 7 and ADVANTEST 9 con-soles can control respectively from to 2 up to 4 loading frames for compression and/or flexural tests on cement and concrete (see page 241 and 247)

1.5E

-3

1.0E

-3

0.5E

-3

-0.5E-3

-1.0E-3

-1.5E-3

-2.0E-3

-2.5E-2

-3.0E-2

-3.5E-2

150100500

400350300250200

Diametral Strainm S

Axial Strain

Forc

e (k

N)

Strain (mm/mm)

174

45

test software

- Set-up of load/displacement/strain ramp and cycles

- Diagrams in real time of:- Stress, displacement, average or single

strain vs. time- Stress vs. displacement- Stress vs. strain- Multi-diagrams display.

- Display in real time of recorded data:

ε1 ε3 P σ1 – σ3 νµε µε kN MPa -

Uniaxial test: example of printout

Uniaxial test: detail of rock sample fitted with 3 strain gages 82-P0392

Uniaxial test: the test is performed on a cylindrical rock core with strain sensors measuring the vertical and diametral strain

- Load and displacement- Cell pressure (triaxial test only)- Axial or radial strain (single strain

gauge or average).- Easy calibration procedure and control- Store of recorded data in ASCII file- Direct access during the test to the list of

the data recorded from the beginning- Possibility to pause the test, change set-

up and continue with the new parame-ters.

Processing and printout

We propose two MS EXCEL data sheets that, by the readings of the ADVANTEST 9, perform: - Uniaxial tests- Stress-strain analysis- Poisson ratio vs. strain plot - Secant and tangent modulus calculation- Triaxial tests - Stress-strain analysis - Poisson ratio vs. strain plot- Failure envelope analysis.

Uniaxial test on a cataclasite rock specimen. The vertical cracks are typical of the post peak. Including No.3 Transducer holders 82-D1260, No.3 Transducers 82-P0331/C and Electric mean device 82-P0331/2

ROCK TESTING

Automatic test systems . . . . . . . . . . . . . . . . . . . . . . . . . . . .


Uniaxial and triaxial tests:

Uniaxial test

3

7

4

1

2

6

5

175

45

The lateral pressure is increased by pro-gramming steps and the corresponding axial load is determined. Substantially the failure point is continuously varied by changing the lateral pressure.

Hoek cells for triaxial tests


Hoek triaxial cells are offered in four models of different size; each one consists of the following:- A cell body 1, complete with two quick

release self sealing couplings, for the introduction of the hydraulic oil and cell pressure, and for air outlet and satura-tion of the chamber respectively.

- Two end caps 2, screwed into the cylin-drical cell body.

- Upper 3 and lower loading caps 4 with spherical coupling

- Two female spherical seatings 5 connec-ted to the loading caps 3 and 4 for the correct transmission of the axial load from the loading frame of the compres-sion machine to the specimen.

- A rubber sealing sleeve 6 to separate the specimen from the cell fluid.

Although each sleeve can be used for seve-ral tests, an order of five spare sleeves is recommended (see accessories). Measurements of axial and radial strain are carried out with the use of electric strain gauges 7, both in vertical and horizontal direction, directly glued on the lateral surface of the specimen. The wiring con-nections are passed within the rubber sleeve through the cell body and loading cap. Each strain gauge must be connected to a proper electric device (see 82-P0070/1) to complete and balance the Wheatstone bridge. The strain gauge measurements can be performed by automatic testing systems described on page 172 or by suita-ble Datalog described on page 178 The cell pressure and saturation pressure for per-meability tests are carried out by the use of appropriate equipment (see page 181).


Rock specimen

Oil inlet

Strain gauges

Cell body

sCode D.C.D.M.A. Specimen size Weight Total height(1)

reference d x h (mm) (kg) mm

45-D0553 AX 30.10 x 60 2.50 21345-D0554 1.5 in. 38.10 x 75 4.00 26445-D0555 BX 42.04 x 85 6.50 26345-D0556 NX 54.74 x 100 13.00 304

(1) Specimen plus loading caps plus spherical seatings

Hoek cells

sCode D.C.D.M.A. Specimen size reference d x h (mm)

45-D0553/1 AX 30.10 x 6045-D0554/1 1.5 in. 38.10 x 7545-D0555/1 BX 42.04 x 8545-D0556/1 NX 54.74 x 100


Hardened steel spherical seat

Rubber sealing sleeve

Spare rubber sleeves

ROCK TESTING

. . . . . . . . . . . . . . . . . . . . . . . . . . . .Automatic test systemsDetermination of Elastic Modulus and strength characteristics of rock specimens in uniaxial and triaxial conditions (continued)


45-D0556/A, 45-D0556/B

45-D0556/H

Schematic view of the Hoek cell with load spread and distance pads within the compression platen of the testing frame

(1) Please refer to the right hand sketch to define the number of required parts depen-ding on the Hoek cell size.

Triaxial TesT

Accessories

s45-D0556/A (1)Pair of load spreader for uniform load distribution

s45-D0556/B (1) Distance pad to reduce the vertical clea-rance of the compression machine

s45-D0556/H Hoek cells holder

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176

M 45-C9034

Compression device for rock core specimens 50 to 55 mm dia., 100 to 110 mm high


The apparatus consists of a two-column frame fitted with an upper platen with spherical seat that moves vertically sustai-ned by a spring. The lower platen is fitted to the base.

Platen dimensions: 55 mm dia., 28 mm thick

Platen minimum hardness: 58 HRC

45-C9034

Adapter For specimen For use Weight set code size with cell approx. (kg)45-D0577/1 AX 45-D0553 1.745-D0577/2 1.5 inch. 45-D0554 1.745-D0577/3 BX 45-D0555 1.545-D0577/4 NX 45-D0556 1.5

Extruder adapters setComprising back plate adapter, two support cell body and shaft head.

45-D0577/A

rock sample extruder

M 45-D0577/A

Specimen extruder

Used to extrude the rock sample from its jacket thus avoiding to empty the confi-ning fluid. It consists of a steel frame with a rack and pinion mechanism. Supplied without adapters, which should be ordered separately. See adapters set.


for uniaxial and triaxial tests

Resistance: 120 + 0.3 % Ohms Warking temperature: -20 to + 80°C

M 82-P0390Linear pattern strain gage, 9.53 mm length

M 82-P0391Linear pattern strain gage, 20 mm length

M 82-P0392Linear pattern strain gage, 30 mm length

M 82-P0393Linear pattern strain gage, 60 mm length Accessories

M 82-P0399/A Strain gage application kit.

M 82-P0398 Electric interface for connecting up to 4 strain gages to MCC8, ADVANTEST 9 and DATALOG.

M 82-P0390/1Contacts for strain gages. 176 pieces.

M 82-P0070/3Excel data sheet for stress strain analysis and elastic modulus processing in uniaxial tests. For printout of test data and proces-sing the following diagrams: Stress Strain curves with axial, radial and volume strain; Secant and Tangent moduli vs. axial strain; Poisson’s ratio vs. axial strain; Radial Strain vs. axial strain.

M 82-P0070/4Excel data sheet for stress strain analysis and failure envelope for triaxial tests. For printout of test data and processing the same data of the 82-P0070/3 data sheet plus the following: Strength Values vs. confining pressures and strength envelope; Mohr circles and failure envelope.

M 45-C9098/D

Lower and upper platen compres-sion device for rock core specimens 100 mm dia.

This device comprises a lower and upper platen 105 mm dia., 55 mm thick, minimum hardness 58 HRC and a clamping device to fit the upper platen of the EN series com-pression machines 300 mm dia. The lower platen can be easily centred on the piston or on a suitable distance piece instead of the standard compression platen of the machine.

A Weight approx.: net 5 kg

Vertical daylight: 112 mm

Total height: 250 mm approx.

B Overall dimensions: 145 mm dia. x 250 mm

A Weight approx.: 10 kg45-C9098/D


ROCK TESTING

Automatic test systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . Determination of Elastic Modulus and strength characteristics of rock specimens in uniaxial and triaxial conditions/ Accessories

Accessories for Hoek cells:

compression device for uniaxial tests LINEAR PATTERN STRAIN GAGES

86-D2999

45

177

typical configuration of an automatic system for uniaxial and triaxial tests on rock specimens

sCode Description Q.ty Q.ty Uniax. Triax.

AXIAL LOAD UNIT

50-C9842 ADVANTEST 9 Servohydraulic control console 1 1 for load application86-D2999 PC cabinet (optional) 1 150-C6600/FR 4000 kN cap. EN compression frame (other models available from 2000 to 3000 kN cap. See page 238) 1 150-C0050/CAL Special calibration of load digital unit assuring Class 1 from 1% of full scale 1 150-C9086 (1) Distance piece dia. 200x100 mm 3 150-C9080 (1) Distance piece dia. 200x30 mm 1 150-C9082 (1) Distance piece dia. 200x50 mm 2 1

CONFINING PRESSURE UNIT50-C7022/S SERCOMP 7 Automatic control console for / 1 constant pressure system in triaxialload testing45-R0023 Three-way connector / 182-P0354 Pressure transducer 700 bar cap. / 2

HOEK CELLS (different sizes available, see page 175 We propose here NX model) 45-D0556 Hoek cell NX 54.7 mm dia. / 145-D0556/A Pair of load spreaders / 145-D0556/B Distance pad / 145-D0556/1 Spare rubber membrane / 545-D0577/A Rock sample extruder / 145-D0577/4 Extruder adapter set for NX specimens / 1

STRAIN READING AND CONTROL (Select the suitable strain gauges within the models listed below)82-P0398 Electric device to complete and compensate up to four Wheatstone bridges with ¼ or ½ bridge set up 1 182-P0399/A Strain gage application kit 1 182-P0390 Strain gage, grid width 4.53x9.53 mm. Pack of 10 1 182-P0391 Strain gage, grid width 3x20 mm. Pack of 10 1 182-P0392 Strain gage, grid width 2x30 mm. Pack of 10 1 182-P0393 Strain gage, grid width 1x60 mm. Pack of 10 1 /82-P0070/3 Excel data sheet for stress-strain analysis and elastic modulus processing for uniaxial tests 1 /82-P0070/4 Excel data sheet for stress-strain analysis and failure envelope for triaxial tests / 1

Reference Standards: ISRM Suggested methods; ASTM D2664, D2938, D3148, D5407PC cabinet

M 86-D2999

PC cabinet for testing systems. 230 V, 50 Hz, 1 ph.

This PC cabinet is a purpose built accessory for use in many laboratory applications, where a PC is required in a testing environ-ment. It is designed to provide PC system protection from airborne contamination such as cement dust. Filtration is achieved by two vented filters in the cabinet. The monitor can be fitted on top of the cabinet and three extractable shelves holds keybo-ards, printer and mouse.

B Overall dimensions: 500x550x915 mm (lxdxh)



ROCK TESTING

. . . . . . . . . . . . . . . . . . . . . . . . . . . .Automatic test systemsDetermination of Elastic Modulus and strength characteristics

of rock specimens in uniaxial and triaxial conditions/ Configuration of a complete testing system

LINEAR PATTERN STRAIN GAGES

Detail of rock sample fitted with 3 strain gauges 82-P0392

PC ACCessory

N O T E In case of uniaxial test on high strenght specimens featuring explosive failure it is suggested the use of distance pieces complete with threaded centering pin which are identified by the suffix / P. Example 50-C9086/P

45

178

pressure systems

M 45-D0558

Low friction manual pressure maintainer for lateral pressure in the Hoek triaxial cells

Used for maintaining constant the desired lateral pressure in the Hoek triaxial cells. The unit comprises a hand pump connec-ted to a special oil reservoir, a precision pressure gauge, a pressure maintainer and a flexible hose 3 m long with 90° quick release coupling.

Max. working pressure: 70 MPa


q STANDARDASTM D2664, D2938, D3148, D5407ISRM Sugg. MethodsEN 14580, EN 1926

IntroductionThe Elastic modulus and strength charac-teristics of rock specimens in uniaxial and triaxial conditions can also be determined in the semiautomatic mode, combining a semiautomatic compression machine with a manual lateral pressure system and with all the other accessories already listed for the automatic system.The basic apparatus should comprise:- Compression testing machine of suf ficient capacity (e.g. our digital model 50-C5632 3000 kN cap.) with additional pressure transducer- Manual or automatic lateral pressure

system (e.g. our models 45-D0588 or 45-D7022/S Sercomp 7)

- Stress and strain rock measurement device by electric strain gauges (e.g. 82-P0908/B Datalog with accessori-es, pressure transducer, electric strain gauges, etc.)

- Hoek cell with distance pads and load spreaders (e.g. 45-D0553, 45-D0556/A, 45-D0556/B, etc.).

The uniaxial test conforming to ASTM D3148 and D2938 is performed without the lateral pressure system. In detail, all requested items, are listed in the Table on page 179

and recording

M 82-P0908/B

8 channel automatic data acquisi-tion and conditioning unit. 110-230 V, 50-60 Hz, 1 ph.

This system is used to measure stress and strain characteristics of rock samples. In the standard configuration 6 channels are set for strain measurements with electric strain gauges; 2 channels are set for load/pressure measurements with transducers. Supplied complete with RS 232 serial com-munication cable.

50-C4622 with 82-P0908/B, 45-D0558, Hoek cell and accessories for triaxial test

ROCK TESTING

Semiautomatic test systems . . . . . . . . . . . . . . . . . . . . . . .


82-P0908/B

Semi-automatic teSt SyStem

Manual lateral

StreSS and Strain meaSurement

Lateral pressure systems/ Stress and strain measurament

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179

typical configuration of a standard semiautomatic system for uniaxial and triaxial tests on rock specimens

sCode Description Q.ty Uniax Q.ty Triax

Axial load unit and test frame50-C5632 Semiautomatic compression testing machine, 3000 kN cap. Digimax 3 dual channel data acquisition and processing system 1 1

50-C0050/CAL Special calibration of load digital unit assuring Class 1 from 1% of full scale 1 1

50-C9080 Distance piece dia. 200x30 mm 1 1

50-C9082 Distance piece dia. 200x50 mm 1 1

Confining pressure 45-D0558 Low friction manual pressure maintainer for lateral pressure / 1

45-R0023 Three-way connector / 2

82-P0354 Pressure transducer 700 bar cap. / 2

Hoekcells (different sizes available, see page 175 We propose here NX model)

45-D0556 Hoek cell NX 54.7 mm dia. / 1

45-D0556/A Pair of load spreaders / 1

45-D0556/B Distance pad / 1

45-D0556/1 Spare rubber membrane / 5

45-D0577/A Rock sample extruder / 1

45-D0557/4 Extruder adapter set for NX specimens. (For other sizes select the sui table adapter. See page 176) / 1

Strain reading and control (Select the suitable strain gauges within the models listed below)

82-P0908/B 8 channels automatic data acquisition and conditioning unit 1 1

82-P0398 Electric device to complete and compensate up to four Wheatstone bridges with ¼ or ½ bridge set up 1 1

82-P0399/A Strain gauge application kit 1 1

82-P0390 Strain gauge, grid width 4.53x9.53 mm. Pack of 10 1 1

82-P0391 Strain gauge, grid width 3x20 mm. Pack of 10 1 1

82-P0392 Strain gauge, grid width 2x30 mm. Pack of 10 1 1

82-P0393 Strain gauge, grid width 1x60 mm. Pack of 10 1 /

82-P0070/3 Excel data sheet for stress-strain analysis and elastic modulus processing for uniaxial tests 1 /

82-P0070/4 Excel data sheet for stress-strain analysis and failure envelope for triaxial tests / 1

Reference Standards: ASTM D2664, D2938, D3148, D5407ISRM Suggested method

Elastic modulus and strength characteristics of rock specimens in uniaxial and triaxial conditions. Configuration of complete testing.

. . . . . . . . . . . . . . . . . . . . . . . .Semiautomatic test systemsROCK TESTING


HardwareNumber of channels: 8Sensors outputs: - Vex 2V DC (common to all channels)- compatible with Wheatstone full bridges (4/4). For use with 1/4 and 1/2 Wheatstone bridges, see accessory 82-P0398Sensors inputs: - 0-20000 microV- sensors impedance from 100 Ohm to 10 kOhmReal resolution: 32000 divisions Sampling rate: adjustable up to 3 samples/sec per channelData storage User interface: membrane keyboard and 128x64 pixel graphic display Communication ports: RS 232 for data download to PC with Controls DATA soft 82-P0908/ SOF, CONTROLS D-TERMINAL, Microsoft HYPERTERMINAL or equivalent or for serial printer 82-P0172.Power supply: 110-230 V, 50-60 Hz, 1 ph.Dimensions: 320x250x110 mm (lxdxh)Weight: 2.5 kg approx.

On-board firmware- Digital calibration of channels with linear and polynomial mode - Data storing can be activated from remote with external trigger - Independent storing of each channel with dedicated memory configurable as roll-over- Easy recall and management of stored readings- Alarm threshold can be activated on each channel- Date and clock function- Selection of the language.


PC software sample screen

Main features:- Displays readings on the PC screen both as numeric values and graphic plots (axes and scales adjustable)- Performs statistical elaboration of groups of readings (min. value, max. value, average value, standard deviation)- Saves measuring sessions generating files- Allows data-files management- MS Windows® 98/2000/ME/XP compatible.

Accessories

s82-P0908/SOF Datasoft software and serial cable for PC connection

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45-D0546

Accessories

s45-D0546/1 Pair of mesh drums, complete with coupling and tanks

of intact core specimens q STANDARDASTM D3967

IntroductionThis test method has been developed to measure the uniaxial tensile strength of rock specimens by the diametral compres-sion of a disk. The splitting tensile strength is calculated as follows:

2 P σt = ___ · _________ π L · D

where:P maximum compressive forceL, D thickness and diameter of rock

disk.

The test specimens shall be a circular disk with a thickness-to-diameter ratio (L/D) between 0.2 and 0.75. The diameter of the specimen shall be at least 10 times greater than the largest mineral grain constituent.A diameter of 54 mm (NX) will general-ly satisfy this criterion. We propose, as an accessory to a suitable compression frame, the 50-C9032 Compression device. Considering the average splitting strength value of different types of rock ranging from 3 to 14 MPa, a load frame of 50 kN max. capacity should be suitable.A suitable testing machine is our Universal tester 70-T0108/E, 50 kN cap. that can operate either with load or displacement control.Our Sales Dept. is at your complete disposal for any assistance you may need.

M 50-C9032

Compression/splitting device for 54 mm dia. rock specimensThis apparatus can be used for splitting tensile strength on rock disk 54 mm dia. Platen dia. is 75 mm. Total height 188 mm.


70-T0108/E equipped with the 50-C9032 device for splitting testing of rock disk

slake durability index


M 45-D0546

Slake durability apparatus. 230 V, 50 Hz, 1 ph.

M 45-D0546/ZSame as above but 110 V, 60 Hz, 1 ph.

M 45-D0546/YSame as above but 220 V, 60 Hz, 1 ph.


This test method has been developed to assess the deterioration of rocks over a period of time when subjected to water immersion. The apparatus consists of a motorised drive unit which is mounted on a baseplate and which can rotate two or four drums at a speed of 20 r.p.m. The tank assemblies are filled with water to a level 20 mm below the drum axis. The test drums are manufactured from 2.00 mm mesh, 140 mm dia. x 100 mm long.


ROCK TESTING

Classification tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


Splitting tenSile teSt

ClassifiCation tests:

Splitting tensile test/ Slake durability

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181Testing equipment for the construction industry

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Permeability of rockROCK TESTING

constant head type

Introduction

This test is performed to measure the water flow through the rock specimen contained in the Hoek cell and subjected to high confining pressure. The hydraulic gradient within the rock sample is supplied by a constant pressure apparatus and the water permeating the sam-ple is collected in a burette. A cou-ple of end caps are also necessary to fit the Hoek cell.

M 28-WF4312

Oil and water constant pressure apparatus for pressure up to 3500 kPa. 230 V, 50 Hz, 1 ph.


This apparatus provides an infinitely varia-ble constant pressure and is used in con-junction with the Hoek cell fitted with the permeability end caps, for the investigation of the permeability of rock at high confi-ning pressures in the laboratory. The apparatus comprises: motorised hydraulic pump; honed piston/spring assembly; precision test gauge 0-3500 kPa range; cylindrical oil/water interchange vessel; valves; 2 kg of high viscosity oil.

Pressure range: 0-3500 kPa

B Dimensions: 310x300x390 mm


45-D0558 45-C7022/S

28-WF4312 with Hoek cell, permeability end caps, burette, support base and metal/glass sleeve

Typical configuration of a Rock permeability test set

permeability end caps

s45-D0553/3 Permeability end cap AX size

s45-D0554/3 Permeability end cap 1.5 in. size

s45-D0555/3 Permeability end cap BX size

s45-D0556/3 Permeability end cap NX size

glass burette and accessories

s86-D1160 Graduated glass burette 25 ml cap. x 0.1 ml div.

s86-D1445 Support base 200x130 mm

s86-D1451 Double sleeve metal/glass

Hoek cells (see page 175)

Accessories

s28-WF4191 Connecting hose to the Hoek cell

s28-WF4302/1 High viscosity oil. 5 l can

sCode Description Q.ty

RockpermeabilitywithinHoekcells28-WF4312 Oil and water constant pressure apparatus for pressure 1 up to 3500 kPa. 230 V, 50 Hz, 1 ph. 28-T0490 Nylon tubing 6x4 mm dia., 20 m coil 145-D0556 (1) Hoek cell NX size 145-D0556/3 (1) Permeability end caps for NX Hoek triaxial cell 45-D0556. 1 Set of two 86-D1160 (1) Graduated glass burette 25 ml cap. x 0.1 ml div. 186-D1445 Support base 200x130 mm complete with rod 10 mm dia. 1 x 500 mm long 86-D1451 Double sleeve metal/glass 145-D0558 (2) Low friction pressure maintainer or 145-C7022/S (2) Automatic control console for constant pressure system 1 in the Hoek triaxial cell. 230 V, 50 Hz, 1 ph. (alternative to 45-D0558, suggested for long term tests)

(1) Or other sizes (2) Normally required/available for the triaxial test (see pages 178 and 241)

Permeability of rock.

Constant pressure apparatus

Costant pressure apparatus

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182

Another important section of rock mechanics involves the study of durability and discontinuities within the rock mass, where the compres-sion and shear strength is lower.The behaviour of joints is particu-larly investigated: they are origina-ted from geological failures, brea-king off the rock mass continuity, along which no sliding mechanism is shown.From the rock mechanics point of view the discontinuities are charac-terised by mechanical strength lower than the original rock matrix and require detailed test investigations.

strengtH of tHe joint wallsIt is conventionally investigated with the Schmidt Hammer (L model). A series of 10 measurements is performed both on the joint walls and on a new failure surface. From the 10 values obtained the 5 lower are rejected and the compression strength is given by the average value of the last 5. This parameter is generally indicated as JCS (Joint Wall Compressive Strength), expressed in MPa.

surface rougHness of tHe jointThis parameter is defined on the joint sur-face with the Barton comb (Profilometer 45-D0556) used to reproduce the rough-ness profile. The line obtained is compared with a scale of roughness profiles, propo-sed by Barton, each of them is specified with a classification number JRC, variable from 0 to 20 (JRC = Joint Roughness Coefficient).

tilt testAn empirical method for an immediate evaluation of the JRC index is obtained with the tilt test (model 45-B0096). It essentially consists of a horizontal plane, upon which the two parts of the sample are placed, laid one upon the other along the joint surface. Then the plane is gradual-ly tilted until the relative displacement of the upper piece of the sample on the lower one is observed.

The equipment is fitted with a lower edge, to stop the lower specimen from sliding, and one goniometer. The tilting angle measured is related to the JRC index with the following:

sHear strengtH of tHe jointIt is obtained from the direct shear test.The peak resistance of a rough joint is calculated from the following relationship (Barton, 1973):

τ = σ · tg (ϕ + ieff)

with

JCS ieff = JRC · log ______

σ

α - ϕR

JRC = ______________

Log (JCS/σ)

ϕR angle of residual shear friction (obtai-ned from the shear test)

σ normal pressure acting on the joint surface, generated by the weight of the upper piece of the sample

JCS joint resistance (measured with the Schmidt Hammer)

Therefore the shear test is performed: - on a smooth joint to directly obtain

the shear friction angle ϕ- on a rough joint to calculate ϕ from

JCS and JRC.

From the above expression it is interesting to observe that, when the normal stress σ equals JCS (compression strength of the joint itself), ieff becomes 0. The mechanical explanation is that, when the joint walls are fractured for the applied high normal pres-sure, the shear resistance of the rock only depends from the shear strength angle ϕ and not from the surface roughness of the joint.For the measurement of the residual shear strength of the joint the direct shear test is also used. The mathematical expres-sion representing the behaviour of residual strength is the Coulomb’s linear failure envelope without cohesion:

τ = σ · tg ϕR

Typical roughness profiles


Behaviour of joints

ROCK TESTING

Behaviour of joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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183Testing equipment for the construction industry

Accessories

s45-D0548/9 High alumina cement for the cementation of the sample in the shear box. 50 kg bag

s82-D1257 Dial gauge 30 mm travel for horizontal displacement x 0.01 mm

s45-D0548/10 Set of 4 dial gauges 10x0.002 mm complete with mounting brackets

45-D0548

45-D0566

One of the pumps is fitted with a pressure maintainer to assure

auniform load during the test

Detail of the shear box apparatus fitted with the 45-D0548/10 accessory to perform the test con-forming to the ASTM D5607 standard

q STANDARD ASTM D5607 (1) ISRM: Suggested method for determining shear strength (1974)

(1) To perform the test conforming to ASTM standard, four dial gauges for verti-cal displacement are requested. See acces-sory 45-D0548/10

M 45-D0548

Rock shear box apparatus. Hand operated


This apparatus was originally developed at Imperial College, London, by Professor E. Hoek. It is a simple and practical method of deter-mining the strength and slope stability of rock, both in the field and in the laboratory. The apparatus consists of a shear box desi-gned to accept rock samples not larger than 115x125 mm, or alternatively cores up to 102 mm dia. The shear box consists of two halves, the upper being connected to two rams for reversible shearing action and the lower con-nected to a ram for normal load application. The loads are recorded by Bourdon tube load gauges.The normal loading system is complete with an adjustable low friction pressure maintainer to absorb volume changes of the specimen during the shearing action and to ensure a constant vertical stress.The apparatus is supplied complete with two 50 kN pumps and manometers and two mould forms used for the correct alignment of the sample before the test with cemen-tation.

Gauge range: 50 kN x 1 kN

B Dimensions: 460x250x600 mm


profilometers

Used for measurement of the roughness profile of rock samples.

M 45-D0566

Profilometer (Barton comb). 300 mm lengthA Weight approx.: 1 kg

M 45-D0566/A

Profilometer (Barton comb). 150 mm lengthA Weight approx.: 0.5 kg

M 45-B0096

Apparatus for measurement of the joint roughness coefficient (Tilt Test)


It is used to calculate the JRC of a rock or of a joint. The equipment consists of an adjustable inclined plane, on which the rock sample (100 mm dia. max.) is placed, separated along the surface where the rou-ghness is to be measured. Then the plane is slowly tilted until sliding of the upper part of the sample on the lower one occurs. From the measured inclination angle it is possible to evaluate the roughness index.

Inclination angle: 0-50°

B Overall dimensions: 265x170x260 mm


45-B0096

MeasureMent of shear strength

Spare parts

s45-D0548/8 Mould former

s45-D0548/1 Load gauge, range 0-50 kN x 1 kN

Roughness measuRement.

TilT TesT

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Behaviour of jointsROCK TESTING

Measurement of shear strengthRoughness measurement. Profilometers / Tilt test

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184

Accessories

s45-D0550/D5 Set of lower and upper platen 52 mm dia. with spherical seat for compression tests

s45-D1717 Clear safety goggles

45-D0550/E

45-D0561 with 45-D0562/A

q STANDARDASTM D5731 - ISRM: Suggested method.

M 45-D0550/E

Digital rock strength index apparatus (Franklin Press)


The apparatus consists of a load frame 60 kN capacity with a hydraulic loading ram actuated by a hand pump. The frame is adjustable to allow for testing sample up to 102 mm dia. A ruler assembled on the frame allows for direct measurement of the distance D between the conical platens before and after the test. The compression load is measured by a pressure transducer with an advanced digital display unit assu-ring the best accuracy and resistance to the failure shocks. The machine, fitted with the accessory 45-D0550/D5, can also be used for compression tests on small cores or cylindri-cal specimens. The apparatus is contained in an easyly transportable plastic case.

Load range: 0-60 kN

Digital display: 2x16 characters

Resolution: 32.000 div.

Load pacer included

Load measured in both kN and MPa

Serial port for PC connection

Accuracy: ± 1%

Case dimensions: 800x500x280 mm

Weight: 15 kg approx.

q STANDARD: ASTM D5873ISRM: Suggested method

M 45-D0561

Rock classification hammer (Schmidt hammer – Low impact energy model)


Used to measure the rebound index on rock cores and samples. The apparatus is simple, easy to use, and is similar to the one used for testing concrete. The level of impact energy only is different: 0.74 Nm. Rock cores are positioned horizontally and the rebound index is obtained from the average of several measurements performed perpendicularly to the longitudinal axis. The unit is supplied complete with carrying case.

B Dimensions of case: 78 mm dia. x 335 mm

Accessories

M 45-D0562/A ASTM rock cradle

Universal model, can hold all standard rock core sample from EX to NX size (21.46 to 54.74 mm dia.) and even more. The appa-ratus comprises a vertical hammer guide fitted to a steel plate of minimum mass conforming to ASTM D5873, and a magne-tic “V” block that can be easily fitted to the steel plate.

B Dimensions: 220 mm dia. x 420 mm high approx.


M 58-C0184

Calibration anvil

q STANDARDEN 12504-2

ASTM C805, D5873

Used for calibration of concrete test ham-mer (models 58-C0181/N) and Rock classi-fication hammer (model 45-D0561). Made of special alloy steel and supplied complete with traceable hardness certificate. It is essential for the periodical laboratory veri-fication of the Rock classification hammer.

B Dimensions: 150 mm dia. x 230 mm height


- Light and portable unit- Sample size up to 102 mm dia.- Accepts irregular shaped samples- Highresolutiondigitaldisplay

battery operated - Resistant to failure shocks- Serial port for PC connection

included

ROCK TESTING

Classification tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


Strength index/ Rock classification hammer

Strength index

Spare parts

s45-D0550/A7 Set of hardened conical platens

s45-D0550/A8 Set of gaskets for cylin-der and pump

Compression strength

Rock Testing Guide

Documents

Transcript of Rock Testing Guide