FprEN ISO 22476-5

Geotechnical investigation and testing - Field testing - Part 5: Prebored pressuremeter test (ISO/FDIS 22476-5:2022)

This document is applicable to pressuremeter tests using cylindrical flexible probes placed in pre-existent boreholes using testing procedures other than the Menard procedure.
Pressuremeter tests following the Menard procedure are provided in ISO 22476-4.
NOTE          A high-pressure flexible pressuremeter probe which contains transducers for the measurement of radial displacements is also known as flexible dilatometer probe or high-pressure dilatometer probe.
This document applies to tests performed in any kind of grounds, starting from soils, treated or untreated fills, hard soils and soft rocks, up to hard and very hard rocks, either on land or offshore.
The parameters derived from this test can include stiffness, strength, initial in-situ stress state and consolidation properties.

Geotechnische Erkundung und Untersuchung - Felduntersuchungen - Teil 5: Vorgebohrter Pressiometerversuch (ISO/FDIS 22476-5:2022)

Dieses Dokument gilt für Pressiometerversuche mit zylindrischen, flexiblen Sonden, die in bereits vorhandene Bohrlöcher eingesetzt werden und die andere Versuchsverfahren als das Menard-Verfahren anwenden.
Pressiometerversuche nach dem Menard-Verfahren sind in ISO 22476 4 beschrieben.
ANMERKUNG   Eine flexible Hochdruck-Pressiometer-Sonde, die Aufnehmer für die Messung von radialen Aufweitungen enthält, wird auch als flexible Dilatometer-Sonde oder Hochdruck-Dilatometer-Sonde bezeichnet.
Dieses Dokument gilt für Versuche, die in jeder Art von Baugrund durchgeführt werden, angefangen bei Böden, behandelten oder unbehandelten Aufschüttungen, harten Böden und weichem Gestein bis hin zu hartem und sehr hartem Gestein, entweder an Land oder vor der Küste.
Die aus diesem Versuch abgeleiteten Parameter können die Steifigkeit, die Festigkeit, den anfänglichen Spannungszustand in situ und die Festigungseigenschaften umfassen.

Reconnaissance et essais géotechniques - Essais en place - Partie 5: Essai au pressiomètre en préforage (ISO/FDIS 22476-5:2022)

Geotehnično preiskovanje in preskušanje - Preskušanje na terenu - 5. del: Preskus v vrtini s presiometrom (ISO/FDIS 22476-5:2022)

General Information

• Status: Not Published
• Publication Date: 15-May-2023
• ICS: 93.020 - Earthworks. Excavations. Foundation construction. Underground works
• Technical Committee: CEN/TC 341 - Geotechnical Investigation and Testing
• Drafting Committee: CEN/TC 341/WG 5 - Borehole expansion tests
• Current Stage: 6055 - CEN Ratification completed (DOR) - Publishing
• Start Date: 16-Mar-2023
• Completion Date: 16-Mar-2023
• Ref Project: kSIST FprEN ISO 22476-5:2023 - Geotechnical investigation and testing - Field testing - Part 5: Prebored pressuremeter test (ISO/FDIS 22476-5:2022)

Relations

• Revises: EN ISO 22476-5:2012 - Geotechnical investigation and testing - Field testing - Part 5: Flexible dilatometer test (ISO 22476-5:2012)
• Effective Date: 18-Jan-2023

Standards Content (Sample)

SLOVENSKI STANDARD
oSIST prEN ISO 22476-5:2022
01-junij-2022

Geotehnično preiskovanje in preskušanje - Preskušanje na terenu - 5. del: Preskus

tlakomera pred vrtanjem (ISO/DIS 22476-5:2022)

Geotechnical investigation and testing - Field testing - Part 5: Prebored pressuremeter

test (ISO/DIS 22476-5:2022)
Geotechnische Erkundung und Untersuchung – Felduntersuchungen – Teil 5:
Vorgebohrter Pressiometerversuch (ISO/DIS 22476-5:2022)
Reconnaissance et essais géotechniques - Essais en place - Partie 5: Essai au
pressiomètre en préforage (ISO/DIS 22476-5:2022)
Ta slovenski standard je istoveten z: prEN ISO 22476-5
ICS:
93.020 Zemeljska dela. Izkopavanja. Earthworks. Excavations.
Gradnja temeljev. Dela pod Foundation construction.
zemljo Underground works
oSIST prEN ISO 22476-5:2022 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN ISO 22476-5:2022
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oSIST prEN ISO 22476-5:2022
DRAFT INTERNATIONAL STANDARD
ISO/DIS 22476-5
ISO/TC 182 Secretariat: BSI
Voting begins on: Voting terminates on:
2022-04-11 2022-07-04
Geotechnical investigation and testing — Field testing —
Part 5:
Prebored pressuremeter test
Reconnaissance et essais géotechniques — Essais en place —
Partie 5: Essai au pressiomètre en préforage
ICS: 93.020
This document is circulated as received from the committee secretariat.
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
ISO/CEN PARALLEL PROCESSING
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 22476-5:2022(E)
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION. © ISO 2022
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oSIST prEN ISO 22476-5:2022
ISO/DIS 22476-5:2022(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2022

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on

the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below

or ISO’s member body in the country of the requester.
ISO copyright office
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Phone: [phone]
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Website: www.iso.org
Published in Switzerland
© ISO 2022 – All rights reserved
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oSIST prEN ISO 22476-5:2022
ISO/DIS 22476-5:2022(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ..................................................................................................................................................................................... 1

3 Terms, definitions and symbols .......................................................................................................................................................... 2

3.1 Terms and definitions ...................................................................................................................................................................... 2

3.2 Symbols and abbreviations ......................................................................................................................................................... 5

4 Equipment ................................................................................................................................................................................................................... 6

4.1 General ........................................................................................................................................................................................................... 6

4.2 Pressuremeter probe ........................................................................................................................................................................ 9

4.3 Connecting lines .................................................................................................................................................................................... 9

4.4 Control unit (CU) ................................................................................................................................................................................... 9

4.5 Measurement and control accuracy ................................................................................................................................. 10

4.5.1 Time ............................................................................................................................................................................................ 10

4.5.2 Pressure and expansion ................................... ......................................................................................................... 10

4.5.3 Display of readings ........................................................................................................................................................ 10

4.5.4 Expansion calibration cylinder .......................................................................................................................... 10

5 Test procedures .................................................................................................................................................................................................10

5.1 Assembly of parts.............................................................................................................................................................................. 10

5.2 Calibration of the testing device and corrections of readings .................................................................. 11

5.3 Pressuremeter test pocket and probe placing ........................................................................................................ 11

5.4 Test execution ........................................................................................................................................... ............................................ 11

5.4.1 Test loading programmes ........................................................................................................................................ 11

5.4.2 Reference loading programmes .........................................................................................................................12

5.4.3 Readings and recordings before and during the test .....................................................................12

5.5 End of test ................................................................................................................................................................................................ 13

5.6 Backfilling of borehole ..................................................................................................................................................................13

5.7 Safety requirements ....................................................................................................................................................................... 13

6 Test results ........................................................................................................................................... ...................................................................13

6.1 General ........................................................................................................................................................................................................13

6.2 Corrected pressure, radial displacement and volume ..................................................................................... 14

6.3 Apparent pressuremeter moduli ......................................................................................................................................... 14

6.4 Results ........................................................................................................................................... .............................................................. 15

6.4.1 Determination of moduli .......................................................................................................................................... 15

6.4.2 Reference loading programme A ...................................................................................................................... 15

6.4.3 Reference loading programme B....................................................................................................................... 16

6.4.4 Reference loading programme C ....................................................................................................................... 17

7 Test report ...............................................................................................................................................................................................................18

7.1 General ........................................................................................................................................................................................................ 18

7.2 Reporting .................................................................................................................................................................................................. 18

7.3 Presentation of test results ......................................................................................................................................................20

Annex A (normative) Calibration and corrections ............................................................................................................................21

Annex B (normative) Performing the test ...................................................................................................................................................29

Annex C (normative) Accuracy and uncertainties .............................................................................................................................35

Bibliography .............................................................................................................................................................................................................................36

iii
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oSIST prEN ISO 22476-5:2022
ISO/DIS 22476-5:2022(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to

the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see

www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 182, Geotechnics.

This second edition cancels and replaces the first edition (ISO 22476-5:2012), which has been technically

revised.
The main changes compared to the previous edition are as follows:

— Title of the document: title of ISO 22476-5 edition 1 was flexible dilatometer. The title of the Edition

2 is different from Edition 1 and ISO 22476-2 includes now provisions for all kinds of prebored

pressuremeters tests.
— A reference loading programme with cyclic loading has been added.
— Calibration procedures have been developed.
A list of all parts in the ISO 22476 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www.iso.org/members.html.
© ISO 2022 – All rights reserved
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oSIST prEN ISO 22476-5:2022
DRAFT INTERNATIONAL STANDARD ISO/DIS 22476-5:2022(E)
Geotechnical investigation and testing — Field testing —
Part 5:
Prebored pressuremeter test
1 Scope

This Part of ISO 22476 is applicable to pressuremeter tests using cylindrical flexible probes placed in

pre-existent boreholes using testing procedures other than the Menard procedure.
For pressuremeter tests following the Menard procedure refer to ISO 22476-4.

NOTE A high pressure flexible pressuremeter probe which contains transducers for the measurement of

radial displacements is also known as flexible dilatometer or high-pressure dilatometer

This standard applies to tests performed in any kind of grounds, starting from soils, treated or

untreated fills, hard soils and soft rocks, up to hard and very hard rocks, either on land or offshore.

The parameters derived from this test may include stiffness, strength, initial in-situ stress state and

consolidation properties.
2 Normative references

The following referenced documents are indispensable for the application of this document. For dated

references, only the edition cited applies. For undated references, the latest edition of the referenced

document (including amendments) applies.

Guide to the expression of uncertainty in measurement (GUM), BIPM/IEC/IFCC/ISO/IUPAC/ IUPAP/

OIML, 1995 (published 1993 Corrected and reprinted, 1995).
EN 1997 (all parts), Eurocode 7: Geotechnical design
EN 16228-1, Drilling and foundation equipment - safety. Common requirements

EN 16228-2, Drilling and foundation equipment - safety. Mobile drill rigs for civil and geotechnical

engineering, quarrying and mining
ENV 13005:1999, Guide to the expression of uncertainty in measurement

ISO 10012, Measurement management systems — Requirements for measurement processes and measuring

equipment

ISO 14688-1, Geotechnical investigation and testing — Identification and classification of soil — Part 1:

Identification and description

ISO 14689-1, Geotechnical investigation and testing – Identification and classification of rock - Part 1:

Identification and description

ISO 22475-1, Geotechnical investigation and testing — Sampling methods and groundwater measurements

— Part 1: Technical principles for the sampling of soil, rock and groundwater

ISO 22476-4, Geotechnical investigation and testing — Field testing — Part 4: Prebored pressuremeter test

by Ménard procedure

ISO 22476-6, Geotechnical investigation and testing — Field testing — Part 6: Self-boring pressuremeter

test
© ISO 2022 – All rights reserved
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oSIST prEN ISO 22476-5:2022
ISO/DIS 22476-5:2022(E)

ISO 22476-8, Geotechnical investigation and testing — Field testing — Part 8: Full displacement

pressuremeter test

ISO 22476-15, Geotechnical investigation and testing — Field testing — Part 15: Measuring while drilling

3 Terms, definitions and symbols
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply:
3.1.1
pressuremeter probe

cylindrical flexible probe which can be expanded by the application of hydraulic pressure and/or

pressurised gas

Note 1 to entry: Note to entry: Pressuremeter probes contains means of measurement of its radial

displacements or volume. A high pressure flexible pressuremeter probe which contains transducers for the

measurement of radial displacements is also known as flexible dilatometer or high pressure dilatometer

3.1.2
flexible dilatometer/high pressure dilatometer

High pressure flexible pressuremeter probe which contains transducers for the measurement of radial

displacements
3.1.3
pressuremeter control unit-

set of suitable devices capable of supplying fluid and/or gas pressure to the probe, to control and take

readings of the probe’s pressure, radial displacements or volume of the measuring cell.

3.1.4
connecting line

cable that connects the control unit to the probe, delivers fluid and/or gas pressure in the measuring

and guard cells
3.1.6
pressuremeter test pocket

circular cylindrical cavity formed in the ground to receive a pressuremeter probe (3.1.1)

3.1.7
pressuremeter borehole

borehole in which pressuremeter pockets with circular cross sections are made in the ground, and into

which the pressuremeter probe (3.1.1) is to be placed.
3.1.8
pressuremeter test

process of expanding the pressuremeter probe so as to pressurize the flexible membrane against the

pocket wall and so measure pressure, radial displacements or volume as a function of time during the

expansion test (see Figure 1).
3.1.9
pressuremeter sounding

the whole series of successive operations in a given borehole i.e. forming pressuremeter pockets and

performing pressuremeter tests in them
3.1.10
seating pressure

pressure during the expansion of the pressuremeter at which the pressuremeter membrane contacts

the pocket wall
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oSIST prEN ISO 22476-5:2022
ISO/DIS 22476-5:2022(E)
3.1.11
nominal radius/diameter of the cavity

radius/diameter of the cavity at the time of first application of the seating pressure at the cavity walls

3.1.12
controlling parameter

variable (pressure, radius displacement or injected volume) used to define the loading programme of

the test according to a pre-determined programme and recorded in the control unit

3.1.13
radial displacement/diameter increase or decrease
Change in pressuremeter probe radius/diameter or in cavity wall displacement
3.1.14
volume increase or decrease
Change in measuring cell volume
3.1.15
pressuremeter curve

graphical plot of pressure versus the associated pocket wall displacement or measuring cell volume

3.1.16
pressuremeter shear modulus (G )
PBP
apparent pressuremeter shear modulus
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oSIST prEN ISO 22476-5:2022
ISO/DIS 22476-5:2022(E)
Key
1 ground surface
2 borehole wall
3 pocket
4 expanding pressuremeter probe
p applied pressure
A-A axial section
B-B cross section
Figure 1 — Example of a prebored pressuremeter test
3.1.17
depth of test

distance between the ground level and the centre of the expanding length of the pressuremeter probe

measured along the borehole axis (see Figure 2).
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oSIST prEN ISO 22476-5:2022
ISO/DIS 22476-5:2022(E)
3.1.18
operator
qualified person who carries out the test
3.1.19
phase

section of the loading or expansion program characterized by a controlling parameter, a loading rate

and a loading direction
3.1.20
loop

sequence of the loading or expansion program including at least an unloading phase and a reloading

phase, and possibly an intermediate hold phase
3.2 Symbols and abbreviations
For the purposes of this international standard the symbols of Table 1 apply.
Table 1 — Symbols
Symbol Description Unit
a Corrected equipment radial displacement or volume loss coeffi- mm.MPa
cient, taking into account calibration cylinder self-deformability
3 -1
cm .MPa
a Raw equipment radial displacement or volume loss coefficient mm.MPa
3 -1
cm .MPa
a Radial displacement or equivalent volume loss taking into mm.MPa
account calibration cylinder self-deformability
3 -1
cm .MPa
d Calibration cylinder inside diameter mm
d Initial external diameter of the pressuremeter probe mm
d Nominal diameter mm
E A Young modulus derived from a prebored pressuremeter test MPa
PBP
G Shear modulus MPa
G First loading pressuremeter shear modulus MPa
G Pressuremeter shear modulus MPa
PBP
G A reloading pressuremeter shear modulus MPa
G Apparent shear modulus of the equipment or system during MPa
sys
unloading-reloading loops
G An unloading pressuremeter shear modulus MPa
G An unloading/reloading pressuremeter shear modulus MPa
URi
k Creep parameter in reference loading programme C mm
L Length of the expanding part of the probe mm
L Length of the measuring segment of the probe mm
L Axial distance between transducer or LVDT section and mem- mm
brane clamping ring
p Corrected pressure MPa
p Constant full relief pressure for loops in reference loading MPa
1.1
programme A
p Pressure loss associated with membrane stiffness
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oSIST prEN ISO 22476-5:2022
ISO/DIS 22476-5:2022(E)
Table 1 (continued)
Symbol Description Unit
p Corrected reversal pressure before loop i MPa
p Average corrected pressure in reference loading programme D MPa
mean
p Minimum corrected pressure in reference loading programme D MPa
min
p Maximum corrected pressure in reference loading programme D MPa
max
p Pressure as read at the measuring unit MPa
p Seating pressure MPa
r Corrected radius mm
r Corrected radius at time t in reference loading programme C mm
1 1
r Corrected radius at time t in reference loading programme C mm
2 2
r Radius correction
r Nominal cavity radius mm
t Time min
T Period in reference loading programme D min
t Time 1 in reference loading programme C min
t Time 2 in reference loading programme C min
ΔV Corrected injected volume cm
ΔV Injected volume correction cm
ΔV Injected volume, as read at the control unit cm
V Total volume cm
z Test depth m
δ Corrected radial displacement mm
δ Radial displacement correction mm
δ Radial displacement, as read at the control unit mm
Δd Increase of diameter, as read at the control unit mm
Δd Corrected diameter increase mm
Δp Pressure increment, as read at the control unit MPa
Δp Corrected pressure increment MPa
ε Cavity strain -
ν Poisson’s ratio -
4 Equipment
4.1 General

The test with the pressuremeter is performed by the expanding of a pressuremeter membrane placed

in the ground (see Figure 1). The pressure and the associated expansion of the probe are measured and

recorded so as to obtain a stress-displacement relationship for the ground as tested.

The equipment to carry out pressuremeter tests shall consist of the components shown in Figure 2.

The following components are mandatory:
— Pressuremeter (No. 8 in Figure 2),
— Connecting line (No. 6 in Figure 2),
— Signal cable (No. 5 in Figure 2),
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oSIST prEN ISO 22476-5:2022
ISO/DIS 22476-5:2022(E)
— Displacement or volume measuring unit (No. 2 in Figure 2),
— Pressure control unit (No. 3 in Figure 2),
— Pressure source (No. 4 in Figure 2),
The following components may be added:
— Pore pressure measuring system,
— Accelerometer or geophones to perform shear wave velocity measurements.
Key
1 setting rods 6 connecting line

2 displacement or volume measuring unit 7 probe rode coupling Sediment collection tube

3 pressure control unit 8 pressuremeter probe
4 pressure source 9 optional data logger
5 signal cable z test depth
Figure 2 — Schematic diagram of pressuremeter equipment

The following components shall be used according to application class of the sounding:

— a control unit (No. 9 in Figure 2);

— sediment collection tube to protect from caving if applicable (No. 12 in Figure 3);

— setting rods (No.1 on Figure 2).
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oSIST prEN ISO 22476-5:2022
ISO/DIS 22476-5:2022(E)

NOTE Sometimes, setting rods are necessary to push the probe into a tight pocket. They also allow

orientation of the instrument if needed. They are also needed in case it becomes difficult to extract the probe at

the end of the test and hammering out is required.
Key
1 control unit (CU): 1a pressurization, differential pressurization and
injection devices
1b pressure and volume measuring devices
1c acquisition, storage and printing out of the data
(required for CU type B and C)
2 connecting lines: 2a line for liquid injection
2b line for gas injection
2c signal cable
3 depth measurement system
4 setting rods
5 pressuremeter probe 5a upper guard cell
5b central measuring cell
5c lower guard cell
6 ground
7 pressuremeter test pocket
8 probe body, hollow
9 probe rod coupling
10 and 11displacement transducers
12 metal insert at the extremities of the
displacement transducers
13 sediment collection tube
14 membrane clamping ring
15 pressure transducer (if applicable)
16 compass (if applicable)

Figure 3 — Sketch of pressuremeter probes a) tri-cellular probe with expansion followed

through the volume of central cell, b) monocellular probe with displacement measured inside

the membrane, c) monocellular probe with displacement measured at the cavity wall

© ISO 2022 – All rights reserved
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oSIST prEN ISO 22476-5:2022
ISO/DIS 22476-5:2022(E)

Preparation of pressuremeter test pocket shall be performed according to ISO 22476-4. The annular

space between borehole wall and the probe, if any, shall be chosen taking into account the measuring

range of the displacement transducers if any. Drilling parameters should be recorded according to

ISO 22476-15. Borehole log should be recorded according to ISO 22475 and ISO 14689.

4.2 Pressuremeter probe

The probe expansion shall be monitored by radial displacement or volume measurement.

The probe shall have a cover in a shape of monocellular (examples of Figure 3b and 3c) or be tricellular

(example Figure 3a).

When small strain measurement (as defined in EN 1997-2) is needed, local displacement measurement

may be implemented in the probe.

Radial displacements shall be measured by electrical transducers on two or more points, placed in the

vicinity of the mid plane(examples in Figures 3b and 3c). The arrangement shown on Figure 3b with

measurement at the inner wall of the membrane shall be primarily used in soils. The arrangement

shown on the Figure 3c with measurement on inserts that penetrate the membrane and directly bear

on the cavity walls shall be primarily used in rocks.

In arrangement shown on figure 3b, because membrane compression influences the readings of

pressure and displacement, proper corrections shall be determined by corresponding calibration (see

A.3).

The expanding length L = 2.L +L of the probe shall exceed 6d . The measuring segment L , if any,

FD g d d d
shall not exceed 1.5d .
If included, pore pressure may be measured in the mid plane of the probe.
4.3 Connecting lines

The pressure connecting line and signal cable connect the control unit to the probe. The pressure

connecting line conveys the fluid to the probe and may be either parallel or coaxial with the signal

cable.
4.4 Control unit (CU)

The control unit shall control the probe expansion and permit the reading of liquid or gas pressure and

displacement or volume as a function of time.
The pressurizing system (3 and 4 in figure 2) shall allow:
— Reaching a pressure defined by the project;

— Implementing a pressure increment of 0,5 MPa as measured on the control unit in less than 20 s;

— Stopping the injection when necessary.
The control unit shall include:

— Equipment to apply the controlling parameters pressurize, and so to inflate or deflate the probe,

and to maintain constant pressures as required during the test;

— Equipment to maintain an appropriate pressure difference between the central measuring cell and

the guard cells if any;
— A device which permits, according to the ty
...