EN ISO 22476-16:2024
(Main)Geotechnical investigation and testing - Field testing - Part 16: Borehole shear test (ISO 22476‑16:2024)
Geotechnical investigation and testing - Field testing - Part 16: Borehole shear test (ISO 22476‑16:2024)
This document is applicable to the borehole shear test using the phicometer procedure, commonly named the phicometer test (etymologically derived from phi for friction angle, co for cohesion and meter for measurement).
The test can be performed in all types of natural soils, fills and artificial soils, which can be saturated or not.
It does not apply to very soft fine soils, very loose coarse soils, medium strong to very strong rocks and natural or artificial soils with a predominance of cobbles having a particle diameter greater than 150 mm.
Generally, the test is applicable in soils with an order of magnitude of their in situ resistance characteristics as follows:
— Ménard pressuremeter limit pressure: 0,4 MPa < plM < 3,5 MPa approximately or more than 4 MPa in granular non-cohesive soils;
— CPT Cone resistance: 1,5 MPa
This document applies only to tests carried out at a depth less than or equal to 30 m.
The parameters derived from this test are the shear strength properties, as the cohesion and angle of friction.
Geotechnische Erkundung und Untersuchung - Felduntersuchungen - Teil 16: Bohrscherversuch mit Phikometer (ISO 22476‑16:2024)
Dieses Dokument ist auf den Bohrloch-Scherversuch nach dem Phikometerverfahren anwendbar, der allgemein als Phikometerversuch bezeichnet wird (die Wortherkunft ergibt sich aus phi für den Reibungswinkel, ko für Kohäsion und meter für Messgerät).
Der Versuch kann in natürlichen Böden, Schüttmaterial und künstlichen Böden aller Arten durchgeführt werden, die gesättigt und ungesättigt sein können.
Er ist nicht auf sehr weiche feine Böden, sehr lockere grobe Böden, mittelstarkes bis sehr starkes Felsgestein sowie natürliche und künstliche Böden, in denen Geröll mit einer Korngröße von mehr als 150 mm vorherrscht, anwendbar.
Im Allgemeinen ist der Versuch anwendbar in Böden, deren In situ-Widerstandscharakteristika größen-ordnungsmäßig wie folgt sind:
- Grenzdruck des Ménard-Pressiometers: ungefähr 0,4 MPa < plM < 3,5 MPa oder mehr als 4 MPa in körnigen, nicht kohäsiven Böden;
- CPT-Spitzenwiderstand: ungefähr 1,5 MPa < qc < 15 MPa, je nach Art des Bodens (siehe Anhang E);
- SPT N: ungefähr 8 < N < 50, je nach Art des Bodens (siehe Anhang E).
Der Versuch kann auch in Böden durchgeführt werden, deren Widerstand außerhalb dieser Anwendbarkeits¬grenzen liegt. Die Repräsentativität der Ergebnisse muss jedoch durch Analyse der PBST-Kurven (siehe Abschnitt 8) beurteilt oder validiert werden.
Dieses Dokument ist nur auf Versuche anwendbar, die in einer Tiefe von nicht mehr als 30 m durchgeführt werden.
Die aus diesem Versuch abgeleiteten Parameter sind die Scherfestigkeitseigenschaften wie Kohäsion und Reibungswinkel.
Reconnaissance et essais géotechniques - Essais en place - Partie 16: Essai de cisaillement en forage (ISO 22476‑16:2024)
Le présent document est applicable à l'essai de cisaillement en forage selon la procédure du phicomètre, couramment appelé essai au phicomètre (dont l'étymologie vient de phi (φ) qui désigne l'angle de frottement, co qui désigne la cohésion et mètre pour faire référence à une mesure).
L'essai peut être effectué dans tous les types de sols naturels, de remblais et de sols artificiels, pouvant être saturés ou non.
Il ne s'applique pas aux sols fins très mous, aux sols grossiers très lâches, aux roches moyennement résistantes à très résistantes ni aux sols naturels ou artificiels avec une prédominance de cailloux dont la granulométrie est supérieure à 150 mm.
En règle générale, l'essai est applicable aux sols dont les caractéristiques de résistance in situ sont de l'un des ordres de grandeur donnés ci-après:
— Pression limite pressiométrique Ménard: 0,4 MPa < plM < 3,5 MPa environ, ou supérieure à 4 MPa dans des sols granulaires non cohésifs;
— Mesure de la résistance au cône par essai de pénétration (CPT): 1,5 MPa < qc < 15 MPa environ, en fonction du type de sol (voir Annexe E);
— SPT N: 8 < N < 50 environ, en fonction du type de sol (voir Annexe E).
L'essai peut également être effectué dans des sols dont la résistance se situe en dehors de ces limites d'application à condition d'évaluer ou de valider la représentativité des résultats par l'analyse des graphiques PBST (voir Article 8).
Le présent document s'applique uniquement aux essais réalisés à une profondeur inférieure ou égale à 30 m.
Les paramètres déduits de cet essai sont les propriétés de résistance au cisaillement, à savoir la cohésion et l'angle de frottement.
Geotehnično preiskovanje in preskušanje - Preskušanje na terenu - 16. del: Strižni preskus v vrtini (ISO 22476-16:2024)
Ta dokument se uporablja za strižni preskus v vrtini z uporabo postopka s fikometrom, ki se običajno imenuje preskus s fikometrom (angleški izraz »phicometer« je etimološka izpeljanka iz besed »phi« za kot trenja, »co« za kohezijo in »meter« za merjenje).
Preskus je mogoče izvajati v vseh vrstah naravnih zemljin, polnil in umetnih zemljin, ki so lahko nasičene ali ne.
Ne uporablja se za zelo mehke drobnozrnate zemljine, zelo rahle grobe zemljine, srednje trde do zelo trde kamne in naravne ali umetne zemljine, v katerih prevladuje kamenje s premerom delcev več kot 150 mm.
Preskus se na splošno uporablja v zemljinah z naslednjim redom velikosti lastnosti odpornosti na mestu uporabe:
– mejni tlak, izmerjen z Ménardovim presiometrom: približno 0,4 MPa < plM < 3,5 MPa oziroma več kot 4 MPa v zrnatih nekohezivnih zemljinah;
– konusna odpornost (preskus CPT): približno 1,5 MPa < qc < 15 MPa, odvisno od vrste zemljine (glej dodatek E);
– vrednost N (preskus SPT): približno 8 < N < 50, odvisno od vrste zemljine (glej dodatek E).
Preskus je mogoče izvesti tudi v zemljinah z odpornostjo, ki je zunaj teh omejitev uporabe, če je reprezentativnost rezultatov ocenjena ali potrjena z analizo grafov PBST (glej točko 8).
Ta dokument se uporablja le za preskuse, ki se izvajajo na globini 30 m ali manj.
Parametri, izpeljani iz tega preskusa, so lastnosti strižne trdnosti, kot sta kohezija in kot trenja.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-januar-2025
Geotehnično preiskovanje in preskušanje - Preskušanje na terenu - 16. del: Strižni
preskus v vrtini (ISO 22476-16:2024)
Geotechnical investigation and testing - Field testing - Part 16: Borehole shear test (ISO
22476-16:2024)
Geotechnische Erkundung und Untersuchung - Felduntersuchungen - Teil 16:
Bohrscherversuch mit Phikometer (ISO 22476-16:2024)
Reconnaissance et essais géotechniques - Essais en place - Partie 16: Essai de
cisaillement en forage (ISO 22476-16:2024)
Ta slovenski standard je istoveten z: EN ISO 22476-16:2024
ICS:
93.020 Zemeljska dela. Izkopavanja. Earthworks. Excavations.
Gradnja temeljev. Dela pod Foundation construction.
zemljo Underground works
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EN ISO 22476-16
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2024
EUROPÄISCHE NORM
ICS 93.020
English Version
Geotechnical investigation and testing - Field testing - Part
16: Borehole shear test (ISO 22476-16:2024)
Reconnaissance et essais géotechniques - Essais en Geotechnische Erkundung und Untersuchung -
place - Partie 16: Essai de cisaillement en forage (ISO Felduntersuchungen - Teil 16: Bohrscherversuch mit
22476-16:2024) Phikometer (ISO 22476-16:2024)
This European Standard was approved by CEN on 2 January 2024.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 22476-16:2024 E
worldwide for CEN national Members.
Contents Page
European foreword . 3
European foreword
This document (EN ISO 22476-16:2024) has been prepared by Technical Committee ISO/TC 182
"Geotechnics" in collaboration with Technical Committee CEN/TC 341 “Geotechnical Investigation and
Testing” the secretariat of which is held by BSI.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by May 2025, and conflicting national standards shall be
withdrawn at the latest by May 2025.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 22476-16:2024 has been approved by CEN as EN ISO 22476-16:2024 without any
modification.
International
Standard
ISO 22476-16
First edition
Geotechnical investigation and
2024-10
testing — Field testing —
Part 16:
Borehole shear test
Reconnaissance et essais géotechniques — Essais en place —
Partie 16: Essai de cisaillement en forage
Reference number
ISO 22476-16:2024(en) © ISO 2024
ISO 22476-16:2024(en)
© ISO 2024
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
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Published in Switzerland
ii
ISO 22476-16:2024(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
3.1 Terms and definitions .1
3.2 Symbols .3
4 Equipment . 4
4.1 General .4
4.2 Phicometer probe .6
4.3 Connection tube line and pulling rods .6
4.3.1 Connection tube line .6
4.3.2 Pulling rods .6
4.4 Equipment at ground surface .8
4.4.1 Pulling device .8
4.4.2 Pressure-volume control unit (CU) .8
4.4.3 Regulation system of the traction speed of the probe .8
4.5 Means of measurement and control .8
4.5.1 Time .8
4.5.2 Pressure, volume and pulling force .8
4.5.3 Axial displacement .9
4.5.4 Display of readings .9
4.5.5 Dimensions of the shearing zone of the probe .9
5 Test procedure . 9
5.1 Checks and measurements before insertion of the probe in the ground .9
5.2 Borehole drilling phase, probe placing phase and zero setting .9
5.3 Minimum spacing between tests .10
5.4 Teeth insertion phase . 12
5.5 Shearing phase .14
5.5.1 Loading program – applied hold pressures in the probe .14
5.5.2 Successive shearing stages under pressure holds .14
5.5.3 End of the test . 15
6 Back-filling of the phicometer borehole .15
7 Safety requirements.15
8 Test results . .16
8.1 General .16
8.2 Shearing curve graph — Shear strength parameters φ and c .16
i i
8.3 Associated graphs .16
8.4 Adjustment and determination of the in situ phicometer angle of friction φ and the in
i
situ phicometer cohesion c .16
i
8.5 Examples of adjustment and determination of the in-situ angle of friction φ and
i
cohesion c .17
i
9 Reporting .18
9.1 General .18
9.2 Field report .18
9.3 Test report .21
9.4 Tests log . 22
Annex A (normative) Characteristics of the phicometer probe .23
Annex B (normative) Calibration, checks and corrections .24
Annex C (normative) Execution of the PBST borehole .28
iii
ISO 22476-16:2024(en)
Annex D (normative) Determination of the shear strength parameters .30
Annex E (informative) Correlations to estimate p from other soil resistance parameters q
lM c
and N .32
Annex F (normative) Accuracy and uncertainties .33
Annex G (informative) Examples of adjustment and determination of the in situ phicometer
angle of friction φ and cohesion c .35
i i
Annex H (informative) Example of installation of the PBST equipment .40
Bibliography . 41
iv
ISO 22476-16:2024(en)
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
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related to conformity assessment, as well as information about ISO's adherence to the World Trade
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This document was prepared by Technical Committee ISO/TC 182, Geotechnics, in collaboration with
the European Committee for Standardization (CEN) Technical Committee CEN/TC 341, Geotechnical
Investigation and Testing, in accordance with the Agreement on technical cooperation between ISO and CEN
(Vienna Agreement).
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.
v
ISO 22476-16:2024(en)
Introduction
The determination of the shear strength of soils is of paramount importance in geotechnical investigation
and testing of soils. The shear resistance of soils and materials, characterised by the friction angle φ and the
cohesion c, represents an important parameter for the geotechnical engineer while studying the stability of
construction works and structures in relation with soils and materials. Usually, this resistance is measured
in the laboratory using triaxial tests or direct shear tests carried out on field samples and only if sampling,
conservation and preparation make it possible to consider the samples as non remolded and sufficiently
representative of the soil in place.
Since the 1960’s, various experimental devices have been designed and developed to determine the shear
strength directly in situ from tests carried out in boreholes, in different soils at different depths.
The study of the bibliography literature shows that the majority of the existing borehole shear tests are
based on the use of probes for applying and maintaining a normal pressure on the walls of the borehole
and then to carry out a shear phase by a linear displacement of the probe on the soil against the walls of the
borehole. The procedure is then repeated through a multistage increase of the normal pressure to obtain
more values relating normal pressure and shear resistance.
The test equipment and apparatuses differ from each other by the geometry and size of the probes and by
the shape of the friction part of these probes and by the procedure for applying normal pressure stages and
shear phases.
[13]
One of the first devices of this kind is the Iowa Borehole Shear Tester (BST) developed in the USA. The
test is performed by placing a bilateral expandable probe, equipped with two diametrically opposed shear
plates in a predrilled borehole, expanding the probe against the wall of the borehole and causing a shear
failure in the soil by pulling the probe axially along the borehole. The size of the shear plates is relatively
small (32,3 cm ) and does not allow testing of soils with coarse elements, which can somewhat limit its field
of application.
[15]
In the early 1970s, H. Mori, in Japan, developed an in situ shearing device called the IST which was used in
many projects. The principle of the test is carried out by generating a shearing force while pulling upwards
a cylindrical expandable probe provided with teeth driven into the wall of the borehole but it is not reported
whether the IST test continues to be performed currently.
[14]
A self-boring in situ friction test (SBIFT), also developed in Japan, allows the evaluation of soil
characteristics as the initial horizontal at rest pressure, and deformation modulus and strength
characteristics (cohesion and internal friction angle) of the soil. The SBIFT possesses a self-boring drilling
functionality that can reduce the disturbance of the tested soil. However, very few data and results are
available to currently validate this device and the characteristics of the soil it provides.
The same way as the SBIFT, a self-boring in situ shear pressuremeter (SBISP), was recently developed in
[12]
China, that allows the evaluation of pressuremetric characteristics as the initial horizontal at rest
pressure, deformation yield pressure and modulus and also strength characteristics (cohesion and internal
friction angle) of the soil. The SBISP possesses a self-boring drilling functionality that can greatly reduce
the disturbance of the tested soil. However, very few data and results are available to currently validate this
device and the characteristics of the soil it provides.
This document applies to the borehole shear test using the phicometer procedure, commonly named the
phicometer borehole shear test (PBST). This test has been invented and developed by Gérard Philipponnat
[10]
in the 1980’s.
This test has been the subject, between 1986 and 1992, of several applied research programs to design the
apparatus and its components and to develop and optimize a common test procedure that can be used in a
majority of soils. Various articles have been published as a result of these researches and since then PBST
tests continue to be carried out currently, for the determination of the shear strength parameters from the
test and to derive values for the undrained shear strength and an estimation of the drained effective shear
[9]
resistance parameters. The test has been standardized in France since 1997.
vi
ISO 22476-16:2024(en)
The borehole shear test using the phicometer covers a four-phases procedure consisting of drilling a
borehole, lowering the probe to the test depth, inflating it into the borehole wall and shearing the soil by
applying a series of steps of controlled radial pressure and simultaneously pulling out the probe with a
constant displacement rate. The test sequences are shown in Figure 1.
a) Borehole drilling b) Probe placing phase: c) Teeth insertion phase: d) Shearing phase: pull-
phase: drilling a phico- lowering the deflated radial expansion of ing on the probe inflated
meter borehole with probe to the test pocket probe and insertion of with a constant radial
casing (if necessary) and depth the annular teeth in the pressure at each multi-
setting up the PBST test borehole wall stage step
pocket in the borehole
bottom
Key
1 ground surface 4 casing (if necessary) 7 probe (inflated state)
2 ground 5 string of rods 8 radial pressure
3 borehole 6 probe (deflated state) 9 pulling force
S cylindrical shear surface
Figure 1 — General arrangement and phases of the phicometer procedure borehole shear test
vii
International Standard ISO 22476-16:2024(en)
Geotechnical investigation and testing — Field testing —
Part 16:
Borehole shear test
1 Scope
This document is applicable to the borehole shear test using the phicometer procedure, commonly named
the phicometer test (etymologically derived from phi for friction angle, co for cohesion and meter for
measurement).
The test can be performed in all types of natural soils, fills and artificial soils, which can be saturated or not.
It does not apply to very soft fine soils, very loose coarse soils, medium strong to very strong rocks and
natural or artificial soils with a predominance of cobbles having a particle diameter greater than 150 mm.
Generally, the test is applicable in soils with an order of magnitude of their in situ resistance characteristics
as follows:
— Ménard pressuremeter limit pressure: 0,4 MPa < p < 3,5 MPa approximately or more than 4 MPa in
lM
granular non-cohesive soils;
— CPT Cone resistance: 1,5 MPa
— SPT N: 8
The test can also be carried out in soils presenting a resistance outside these application limits as long as the
representativeness of the results is assessed or validated by the analysis of the PBST graphs (see Clause 8).
This document applies only to tests carried out at a depth less than or equal to 30 m.
The parameters derived from this test are the shear strength properties, as the cohesion and angle of
friction.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 10012, Measurement management systems — Requirements for measurement processes and measuring
equipment
ISO 22475-1, Geotechnical investigation and testing — Sampling methods and groundwater measurements —
Part 1: Technical principles for the sampling of soil, rock and groundwater
3 Terms, definitions and symbols
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO 22476-16:2024(en)
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1.1
borehole shear test
process during which a special shearing probe is installed in a borehole at a defined depth and inflated
against the borehole wall and pulled to determine the resulting shear resistance of the soil
Note 1 to entry: This process is repeated with a succession of increased maintained normal pressure steps so as to
obtain a pressure versus shear stress relation of the soil.
3.1.2
phicometer borehole shear test
PBST
shear test performed in a phicometer borehole (3.1.4) with the phicometer probe (3.1.6) and the phicometer
test procedure
Note 1 to entry: See Clause 5 for the phicometer test procedure.
3.1.3
phicometer
whole equipment which is used to carry out a phicometer borehole shear test (3.1.2)
3.1.4
phicometer borehole
part of a borehole in which the phicometer test pocket (3.1.5) is to be set up
Note 1 to entry: See 5.2.
3.1.5
phicometer test pocket
cylindrical cavity with a circular section made in a borehole and in which the phicometer probe (3.1.6) is
placed, brought into contact and pulled upwards during the test phases
3.1.6
phicometer probe
cylindrical expandable probe with annular shearing teeth, used to carry out a phicometer borehole shear test
(3.1.2)
Note 1 to entry: See 4.2 and Figure 3.
3.1.7
phicometer test diagram
set of plots resulting from the PBST (3.1.2) test and allowing the determination of the shear resistance of the soil
Note 1 to entry: See Clause 8 and Figure 6.
3.1.8
phicometer cohesion
in situ cohesion c obtained from the phicometer test diagram (3.1.7)
i
3.1.9
phicometer angle of friction
in situ angle of shear friction φ obtained from the phicometer test diagram (3.1.7)
i
3.1.10
depth of test
distance between the ground level and the centre of the shearing zone of the phicometer probe measured
along the borehole axis
ISO 22476-16:2024(en)
3.1.11
operator
technician trained in carrying out PBST tests, in accordance with this document
3.2 Symbols
For the purposes of this document, the symbols of Table 1 apply.
Table 1 — Symbols
Symbol Description Unit
T Pulling force on the probe kN
T Maximum pulling force kN
l
V Volume injected into the measuring cell of the probe as read on the cm
control unit
V Volume injected into the measuring cell of the probe at the beginning cm
d
of the application of the pulling force (V = V )
d 60
V Volume injected into the measuring cell of the probe at the end of the cm
f
application of pulling force
V Volume injected into the measuring cell of the probe after 30 s under cm
a constant pressure phase
V Volume injected into the measuring cell of the probe after 60 s under cm
a constant pressure phase
d Initial diameter of the probe at rest in the shearing zone (see Figure 3) mm
s0
c phicometer cohesion measured in situ by the PBST kPa
i
d Diameter of the probe in the shearing zone after injection of a volume mm
s
V (see Figure 3)
d Diameter of the pocket at the level of the test mm
t
d Outside diameter of the measuring cell of the probe mm
c
l Slots length of the expansible shear tube mm
t
l Distance between the rings of the measuring cell of the probe mm
c
l Conventional length of the shearing zone (see Figure 3) mm
s
N Standard penetration test SPT Blow count (see ISO 22476-3) -
p Conventional radial pressure applied to the ground after corrections kPa
c
p Probe stiffness pressure loss determined by calibration kPa
e
p Pressure due to the injection liquid column in the probe (between kPa
h
z and z )
c s
p Ménard pressuremeter limit pressure (see ISO 22476-4) MPa
IM
p Pressure of the liquid injected into the phicometer measuring cell, kPa
r
read at the level z of the control unit (CU)
c
p Pressure of the liquid at the centre of the measuring cell kPa
z
q Cone penetration resistance (see ISO 22476-1 or ISO 22476-12) MPa
c
t Time s
v Rate of axial displacement of the probe during the pulling phase mm/min
z Elevation, ascending above datum m
z Elevation of the ground surface level at the location of the test m
z Elevation of the pressure measuring device of the liquid injected into m
c
the phicometer measuring cell
z Elevation of the drilling fluid in the borehole m
e
z Initial level of water or mud measured in the borehole before the m
ei
beginning of the test
ISO 22476-16:2024(en)
TTaabbllee 11 ((ccoonnttiinnueuedd))
Symbol Description Unit
z Final level of water or mud measured in the borehole after the end m
ef
of the test
z Elevation of the centre of the shearing zone of the phicometer probe m
s
at the beginning of the test
z Elevation of the ground water table (or free water surface in a marine m
w
or river environment)
γ Unit weight of the liquid injected into the measuring cell kN/m
l
γ Unit weight of water kN/m
w
Δl Axial displacement of the probe during shearing mm
Δp Loading pressure increment kPa
Δt Duration of a pressure hold at a loading stage s
Δt Duration of a loading pressure hold during the preliminary phase s
p
ΔV Injected volume change from 30 s to 60 s after reaching the pressure cm
hold
φ Phicometer angle of friction measured in situ with the phicometer °
i
borehole shear test
τ Shear stress kPa
τ Conventional limit shear stress kPa
l
4 Equipment
4.1 General
The equipment to carry out phicometer borehole shear tests shall consist of the following components:
— phicometer probe,
— pressure – volume control unit (CU),
— a line to connect the probe to the CU,
— a pulling device placed on a reaction base on the ground surface and linked to the probe with pulling rods,
— a device to control the axial shearing displacement rate,
— means of measurement and display of pressure, volume, pulling force, axial displacement and the external
diameter of the shearing zone of the probe.
The equipment can also include a data logger.
A phicometer borehole shear test (PBST) device assembly is shown in Figure 2.
An example of installation of the PBST equipment is shown in Annex H.
ISO 22476-16:2024(en)
Key
1 borehole 3 string of rods 5 borehole casing (if necessary)
2 phicometer probe 4 connecting line 6 reaction base
2a expansible slotted tube 2c shearing zone mobilized by the
probe teeth
2b annular teeth 2d inflatable measuring cell
A data logger (optional) B2 volume measurement C2 pulling device with timer
B pressure-volume control unit (CU) B3 display of readings D axial displacement control
B1 pressure regulator & injection device C1 measurement of pulling force
Figure 2 — Diagram of the PBST test device assembly and its components
ISO 22476-16:2024(en)
4.2 Phicometer probe
The phicometer probe is shown in Figure 3. It consists of a steel slotted device, called “expandable slotted
shear tube” in which a radially expandable cylindrical cell called “measuring cell” is placed.
The expandable slotted shear tube is a hollow steel cylinder rigidly connected to the pulling rods to ensure
its operation and to transmit the pulling force to the probe from the surface of the ground. It is designed
with different parts featuring:
— a central shearing zone, made up of six initially jointed rigid plates, parallel to the axis of the probe and
comprising ten annular teeth, regularly spaced vertically;
— two guard zones, made up of metal strips acting as a spring;
— an inflatable measuring cell placed at the level of the central shearing zone inside the expandable slotted
shear tube and which is composed of a steel core, a deformable flexible membrane and a tube for liquid
injection used to inflate this cell and to measure its volume.
The characteristics of the probe shall be as given in Annex A. Two types of deformable flexible rubber
membranes exist:
— a standard membrane;
— a reinforced membrane.
The standard membrane is used for all soil types.
The reinforced membrane is exclusively used for aggressive soils where damaging and bursting of the cell
probe occurs frequently.
4.3 Connection tube line and pulling rods
4.3.1 Connection tube line
The flexible tube line connecting the pressure volume control unit to the probe is used to inject the fluid in
the measuring cell.
The expansion coefficient of this line shall be lower than 0,1 cm /MPa per meter of line.
4.3.2 Pulling rods
A string of steel rods connects the probe to the equipment placed on the ground surface. The resistance of
this string of rods shall withstand the efforts and stresses generated by the test during all its phases.
The elongation of the drill string shall remain less than 0,05 % of its total length.
The section of the rods and their fittings shall allow free sliding of the drill string in the borehole.
The part of the pulling rods above the ground surface is threaded over all its length, to allow the adjustment
of the locking system of the string of rods on the pulling device (see 4.4.1).
ISO 22476-16:2024(en)
Key
1 expandable slotted shear tube 2 steel core of the inflatable measuring 3 measuring cell membrane
cell, placed between two spacers
4 tube line for liquid injection 5 purge 6 rings for tightening of the membrane
7 joints 8 liquid for inflating the membrane 9 annular teeth of the shearing zone
10 rods-probe coupling system 11 probe shearing zone 12 probe guard zones
NOTE The symbols in Figure 3 are defined in Table A.1.
Figure 3 — Phicometer probe
ISO 22476-16:2024(en)
4.4 Equipment at ground surface
The equipment includes:
— a pulling device;
— a pressure-volume control unit (CU) allowing the pressurisation and the expansion of the probe;
— a regulation system to control the traction pulling speed of the probe.
4.4.1 Pulling device
The pulling device includes:
— A reaction base, with optional plates, for the distribution of loads on the ground surface.
— A hollow cylinder jack with a diameter hole allowing the upper end of the pulling rods string to pass
freely and for axially tensioning the rods string and the connected probe.
— A device for locking the upper end of the pulling rods string above the hollow cylinder jack.
— A device that measures the pulling force. This device placed between the probe and the locking system
can be either at the ground surface or in the borehole.
4.4.2 Pressure-volume control unit (CU)
Placed at the ground surface, the pressure-volume control unit allows to ensure the expansion of the probe
and to measure, according to time, the pressure as well as the volume of the liquid injected in the measuring
cell of the probe.
The pressurizing device of the CU shall enable to:
— reach a pressure of at least 1,5 MPa;
— keep constant the pressure in the measuring cell during the stages of the test;
— set and apply a pressure increment in less than 20 s.
NOTE A pressure-volume control unit such as that used for the Ménard pressuremeter test (see ISO 22476-4) is
appropriate. In that case, only the liquid circuit of the central measuring cell of this unit is used.
4.4.3 Regulation system of the traction speed of the probe
The regulation system is intended to obtain and to keep constant the rate of displacement of the pulling rods
and the connected probe during the stages of shearing. The displacement is measured by comparison to a
fixed reference mark.
4.5 Means of measurement and control
4.5.1 Time
The means used shall allow a measurement of time with an uncertainty lower than 2 s.
4.5.2 Pressure, volume and pulling force
The maximum uncertainties of the measuring instruments of pressure, of the volume and of the pulling
force shall not exceed the values indicated in Annex F.
ISO 22476-16:2024(en)
4.5.3 Axial displacement
The means used to measure the axial displacement shall allow a measurement of displacement with an
uncertainty not exceeding the value indicated in Annex F.
4.5.4 Display of readings
On the site, the operators shall be able to have simultaneous real-time visualisation or display of the following
measured readings: time, pressure, volume of the injected liquid in the measuring cell, shear displacement
and pulling force.
4.5.5 Dimensions of the shearing zone of the probe
The external diameter d of the shearing zone of the probe is measured with a slide caliper at least at each
s
calibration of the probe (see B.2.2), within a tolerance of 0,1 mm. The length l of the shearing zone of the
s
probe and the dimensions of its annular teeth are defined in Table A.1.
5 Test procedure
The following operations shall be successively carried out, according to the flow chart shown in Figure 4.
In Figure 4:
— a pressure hold corresponds to a step during when the pressure p is maintained constant;
r
— a loading stage corresponds to a stage where the pressure in the probe is set and regulated to a given
value as defined in 5.4 and Table 2 during the loading phase;
— a loading phase corresponds to the successive loading stages and pressure holds applied either during
the teeth insertion phase or during the shearing phases;
— a shearing stage corresponds to the stage of pulling up the inflated phicometer probe at a constant speed
of 2 mm/min, under a constant pressure during the shearing phase;
— the shearing phase corresponds to the successive application of the shearing stages as defined in Table 2
in function of p and p .
lM h
5.1 Checks and measurements before insertion of the probe in the ground
Before inserting the probe into the borehole, the calibrations and controls of correct operation described in
Annex B shall have been carried out.
The level of water or drilling mud in the borehole is recorded right before the insertion of the probe.
5.2 Borehole drilling phase, probe placing phase and zero setting
To carry out a borehole shear test with the phicometer procedure, it is necessary to create a cylindrical test
pocket, by performing a preliminary drilled phicometer borehole descending below the test level.
The drilling techniques of the phicometer borehole for the installation of the phicometer probe shall meet
the specifications of Annex C.
The choice between the different drilling techniques and tools is made according to the soil type, in order to
achieve a cylindrical test zone on the borehole wall with minimum disturbance and create the phicometer
test pocket. The direct driving of the phicometer probe into the soil is not allowed.
The distance between the top of the phicometer borehole and the centre of the phicometer test pocket (i.e.
the center of the shearing zone of the phicometer probe) shall not be less than 1,0 m.
ISO 22476-16:2024(en)
The drilling above the phicometer borehole can be carried out in a diameter greater or equal to the
phicometer borehole diameter.
In most cases, it remains necessary to support the borehole walls by using drilling mud and/or by placing
a casing.
In the case where two successiv
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