SIST EN ISO 17892-10:2019
(Main)Geotechnical investigation and testing - Laboratory testing of soil - Part 10: Direct shear tests (ISO 17892-10:2018)
Geotechnical investigation and testing - Laboratory testing of soil - Part 10: Direct shear tests (ISO 17892-10:2018)
This document specifies two laboratory test methods for the determination of the effective shear
strength of soils under consolidated drained conditions using either a shearbox or a ring shear device.
This document is applicable to the laboratory determination of effective shear strength parameters for
soils in direct shear within the scope of geotechnical investigations.
The tests included in this document are for undisturbed, remoulded, re-compacted or reconstituted
soils. The procedure describes the requirements of a determination of the shear resistance of a
specimen under a single vertical (normal) stress. Generally three or more similar specimens from
one soil are prepared for shearing under three or more different vertical pressures to allow the shear
strength parameters to be determined in accordance with Annex B.
Special procedures for preparation and testing the specimen, such as staged loading and pre-shearing
or for interface tests between soils and other materials, are not covered in the procedure of this
document.
NOTE This document fulfils the requirements of the determination of the drained shear strength of soils in
direct shear for geotechnical investigation and testing in accordance with EN 1997-1 and EN 1997-2.
Geotechnische Erkundung und Untersuchung - Laborversuche an Bodenproben - Teil 10: Direkte Scherversuche (ISO 17892-10:2018)
Dieses Dokument legt zwei Laborprüfverfahren zur Bestimmung der effektiven Scherfestigkeit von Böden unter konsolidierten, drainierten Bedingungen fest, bei denen entweder ein Rahmenschergerät oder ein Ringschergerät verwendet wird.
Dieses Dokument gilt für die Laborbestimmung der effektiven Scherfestigkeitsparameter für Böden in direkten Scherversuchen innerhalb des Anwendungsbereiches geotechnischer Untersuchungen.
Die in dieses Dokument aufgenommenen Versuche gelten für ungestörte, gestörte, wiederverdichtete oder aufgearbeitete Böden. Das Verfahren beschreibt die Anforderungen zur Bestimmung des Scherwiderstands eines Probekörpers unter einer einzigen vertikalen (Normal-)Spannung. Im Allgemeinen werden drei oder mehr ähnliche Probekörper aus einem Boden für das Abscheren unter drei oder mehr verschiedenen vertikalen Spannungen hergestellt, um die Scherfestigkeitsparameter in Übereinstimmung mit Anhang B bestimmen zu können.
Spezielle Verfahren für die Herstellung und Prüfung von Probekörpern, z. B. stufenweise Belastung und Vorscheren (Anscheren), oder für Grenzflächenuntersuchungen zwischen Böden und anderen Materialien sind nicht Teil des Verfahrens in diesem Dokument.
ANMERKUNG Das vorliegende Dokument erfüllt die Anforderungen an die Bestimmung der drainierten Scherfestigkeit von Böden bei direktem Scheren für die geotechnische Erkundung und Untersuchung nach EN 1997 1 und EN 1997 2.
Reconnaissance et essais géotechniques - Essais de laboratoire des sols - Partie 10: Essai de cisaillement direct (ISO 17892-10:2018)
Le présent document spécifie deux méthodes de détermination de la résistance au cisaillement effective des sols dans des conditions consolidées drainées par essais de laboratoire en utilisant soit une boîte de cisaillement, soit un dispositif de cisaillement annulaire.
Ce document s'applique à la détermination en laboratoire des paramètres de résistance au cisaillement effective des sols en conditions de cisaillement direct dans le cadre d'investigations géotechniques.
Les essais présentés dans ce document s'appliquent aux sols non remaniés, remoulés, recompactés ou reconstitués. La procédure décrit les exigences applicables à la détermination de la résistance au cisaillement d'une éprouvette soumise à une contrainte verticale (normale) unique. En général, au moins trois éprouvettes similaires d'un même sol sont préparées en vue de les soumettre au cisaillement sous au moins trois pressions verticales différentes afin de pouvoir déterminer les paramètres de résistance au cisaillement conformément à l'Annexe B.
Les procédures spéciales de préparation et d'essai des éprouvettes, telles que le chargement par étapes et le pré-cisaillement, ou destinées aux essais d'interface entre les sols et les autres matériaux, ne sont pas couvertes par la procédure du présent document.
NOTE Le présent document répond aux exigences applicables à la détermination de la résistance au cisaillement drainé des sols soumis à un cisaillement direct pour la reconnaissance et les essais géotechniques conformément aux normes EN 1997‑1 et EN 1997‑2.
Geotehnično preiskovanje in preskušanje - Laboratorijsko preskušanje zemljin - 10. del: Neposredni strižni preskus (ISO 17892-10:2018)
Ta dokument določa dve laboratorijski preskusni metodi za določevanje efektivne strižne trdnosti zemljin v konsolidiranih dreniranih pogojih s strižnikom ali pripomočkom za krožno striženje. Ta dokument se uporablja za laboratorijsko določevanje parametrov efektivne strižne trdnosti za zemljine v neposrednem strigu, ki spada na področje uporabe geotehničnega preiskovanja.
Preskusi iz tega dokumenta so namenjeni za neporušene, ponovno pregnetene, ponovno zgoščene ali obdelane zemljine. V postopku so opisane zahteve za določevanje strižne odpornosti primerka pri enkratni navpični (normalni) obremenitvi. Običajno so pripravljeni trije ali več primerkov za striženje pod tremi ali več različnimi navpičnimi pritiski, da se lahko določijo parametri strižne trdnosti v skladu z dodatkom B.
Posebni postopki za pripravo in preskušanje primerka, kot sta stopenjska obremenitev in predstriženje,
oziroma za vmesne preskuse med zemljinami in drugim materialom v postopku iz tega dokumenta niso obravnavani.
OPOMBA: Ta dokument izpolnjuje zahteve za določevanje drenirane strižne trdnosti zemljin v neposrednem strigu za geotehnično preiskovanje in preskušanje v skladu s standardoma EN 1997-1 in EN 1997-2.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 17892-10:2019
01-marec-2019
1DGRPHãþD
SIST-TS CEN ISO/TS 17892-10:2004
SIST-TS CEN ISO/TS 17892-10:2004/AC:2010
*HRWHKQLþQRSUHLVNRYDQMHLQSUHVNXãDQMH/DERUDWRULMVNRSUHVNXãDQMH]HPOMLQ
GHO 1HSRVUHGQLVWULåQLSUHVNXV ,62
Geotechnical investigation and testing - Laboratory testing of soil - Part 10: Direct shear
tests (ISO 17892-10:2018)
Geotechnische Erkundung und Untersuchung - Laborversuche an Bodenproben - Teil
10: Direkte Scherversuche (ISO 17892-10:2018)
Reconnaissance et essais géotechniques - Essais de laboratoire des sols - Partie 10:
Essai de cisaillement direct (ISO 17892-10:2018)
Ta slovenski standard je istoveten z: EN ISO 17892-10:2018
ICS:
13.080.20 Fizikalne lastnosti tal Physical properties of soils
93.020 Zemeljska dela. Izkopavanja. Earthworks. Excavations.
Gradnja temeljev. Dela pod Foundation construction.
zemljo Underground works
SIST EN ISO 17892-10:2019 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 17892-10:2019
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SIST EN ISO 17892-10:2019
EN ISO 17892-10
EUROPEAN STANDARD
NORME EUROPÉENNE
December 2018
EUROPÄISCHE NORM
ICS 13.080.20; 93.020 Supersedes CEN ISO/TS 17892-10:2004
English Version
Geotechnical investigation and testing - Laboratory testing
of soil - Part 10: Direct shear tests (ISO 17892-10:2018)
Reconnaissance et essais géotechniques - Essais de Geotechnische Erkundung und Untersuchung -
laboratoire des sols - Partie 10: Essai de cisaillement Laborversuche an Bodenproben - Teil 10: Direkte
direct (ISO 17892-10:2018) Scherversuche (ISO 17892-10:2018)
This European Standard was approved by CEN on 29 November 2018.
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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey 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
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 17892-10:2018 E
worldwide for CEN national Members.
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SIST EN ISO 17892-10:2019
EN ISO 17892-10:2018 (E)
Contents Page
European foreword . 3
2
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SIST EN ISO 17892-10:2019
EN ISO 17892-10:2018 (E)
European foreword
This document (EN ISO 17892-10:2018) 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 June 2019, and conflicting national standards shall be
withdrawn at the latest by June 2019.
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.
This document supersedes CEN ISO/TS 17892-10:2004.
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, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 17892-10:2018 has been approved by CEN as EN ISO 17892-10:2018 without any
modification.
3
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SIST EN ISO 17892-10:2019
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SIST EN ISO 17892-10:2019
INTERNATIONAL ISO
STANDARD 17892-10
First edition
2018-11
Geotechnical investigation and
testing — Laboratory testing of soil —
Part 10:
Direct shear tests
Reconnaissance et essais géotechniques — Essais de laboratoire
des sols —
Partie 10: Essai de cisaillement direct
Reference number
ISO 17892-10:2018(E)
©
ISO 2018
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SIST EN ISO 17892-10:2019
ISO 17892-10:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018
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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved
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SIST EN ISO 17892-10:2019
ISO 17892-10:2018(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 Apparatus . 3
5.1 General . 3
5.2 Shear devices . 4
5.2.1 Shearbox test apparatus . 4
5.2.2 Ring shear apparatus . 5
5.3 Loading-devices . 8
5.4 Measuring devices. 8
5.4.1 Load measuring devices . 8
5.4.2 Torque measuring devices . 8
5.4.3 Displacement measuring devices . 8
5.5 Ancillary apparatus . 9
6 Test procedure . 9
6.1 General requirements . 9
6.2 Preparation of specimen. 9
6.2.1 General requirements and selection of the preparation method . 9
6.2.2 General requirements for preparation of specimens from undisturbed samples 10
6.2.3 Trimming from extruded or block samples .10
6.2.4 Extrusion from a tube of diameter larger than the mould and cutter .10
6.2.5 Preparation of laboratory fabricated specimens .11
6.3 Measurements before testing .11
6.4 Equipment preparation .11
6.5 Consolidation .12
6.6 Shearing .14
7 Test results .15
7.1 Water content .15
7.2 Initial dry density .15
7.3 Initial bulk density .15
7.4 Initial void ratio .16
7.5 Initial degree of saturation .16
7.6 Void ratio during testing .16
7.7 Stresses and displacements .16
7.7.1 Shearbox .16
7.7.2 Ring shear .16
7.8 Plotting .17
8 Test report .17
8.1 Mandatory reporting .17
8.2 Optional reporting .18
Annex A (normative) Calibration, maintenance and checks .19
Annex B (informative) Additional calculations for effective strength parameters .22
Bibliography .23
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SIST EN ISO 17892-10:2019
ISO 17892-10:2018(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 the European Committee for Standardization (CEN) Technical
Committee CEN/TC 341, Geotechnical Investigation and Testing, in collaboration with ISO Technical
Committee ISO/TC 182, Geotechnics, in accordance with the Agreement on technical cooperation
between ISO and CEN (Vienna Agreement).
This first edition cancels and replaces ISO/TS 17892-10:2004, which has been technically revised. It
also incorporates the Technical Corrigendum ISO/TS 17892-10:2004/Cor 1:2006.
The main changes compared to the previous edition are as follows:
— general revision of the text and figures and addition of specimen preparation procedures;
— inclusion of two types of ring shear apparatus; Type A wherein failure occurs at the depth in the
specimen defined by the split specimen container and Type B wherein the location of the failure
surface is not defined by the apparatus;
— addition of Annex A on calibration, maintenance and checks;
— addition of Annex B on additional calculations for effective strength parameters.
A list of all the parts in the ISO 17892 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.
iv © ISO 2018 – All rights reserved
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SIST EN ISO 17892-10:2019
ISO 17892-10:2018(E)
Introduction
This document provides laboratory test methods for the determination of the effective shear strength
of soils by direct shear within the international field of geotechnical engineering.
The tests have not previously been standardized internationally. It is intended that this document
presents broad good practice and significant differences with national documents are not anticipated.
It is based on international practice (see Reference [1]).
This document specifies two methods for the determination of the effective shear strength of soils
under consolidated drained conditions using either a shearbox or a ring shear device.
The shearbox test is generally used for the determination of peak effective shear strength parameters
of soils. The ring shear test is generally used for the determination of residual effective shear strength
parameters of fine grained soils. Residual effective shear strength parameters can also be obtained from
shearbox tests and peak effective shear strength parameters can also be obtained from ring shear tests.
The test method consists of placing the test specimen in the direct shear device, applying a pre-
determined vertical stress, providing for draining (and wetting if required) of the test specimen,
consolidating the specimen under vertical stress and then shearing the specimen. This shearing is
imposed by displacing one part horizontally, relatively with respect to the other part of the specimen at
a constant rate of shear-deformation. The shearing force and the horizontal and vertical displacements
are measured as the specimen is sheared. Shearing is applied slowly enough to allow excess pore
pressures to dissipate by drainage so that effective stresses are equal to total stresses.
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SIST EN ISO 17892-10:2019
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SIST EN ISO 17892-10:2019
INTERNATIONAL STANDARD ISO 17892-10:2018(E)
Geotechnical investigation and testing — Laboratory
testing of soil —
Part 10:
Direct shear tests
1 Scope
This document specifies two laboratory test methods for the determination of the effective shear
strength of soils under consolidated drained conditions using either a shearbox or a ring shear device.
This document is applicable to the laboratory determination of effective shear strength parameters for
soils in direct shear within the scope of geotechnical investigations.
The tests included in this document are for undisturbed, remoulded, re-compacted or reconstituted
soils. The procedure describes the requirements of a determination of the shear resistance of a
specimen under a single vertical (normal) stress. Generally three or more similar specimens from
one soil are prepared for shearing under three or more different vertical pressures to allow the shear
strength parameters to be determined in accordance with Annex B.
Special procedures for preparation and testing the specimen, such as staged loading and pre-shearing
or for interface tests between soils and other materials, are not covered in the procedure of this
document.
NOTE This document fulfils the requirements of the determination of the drained shear strength of soils in
direct shear for geotechnical investigation and testing in accordance with EN 1997-1 and EN 1997-2.
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 17892-1, Geotechnical investigation and testing — Laboratory testing of soil — Part 1: Determination
of water content
ISO 14688-1, Geotechnical investigation and testing — Identification and classification of soil — Part 1:
Identification and description
ISO 386, Liquid-in-glass laboratory thermometers — Principles of design, construction and use
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological 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/
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SIST EN ISO 17892-10:2019
ISO 17892-10:2018(E)
3.1
direct shear test
test whereby a specimen of soil is laterally restrained and sheared along a mechanically induced
horizontal plane while subjected to a vertical stress applied normal to that plane
3.2
shearbox test
direct shear test (3.1) whereby a specimen is placed in a rigid square or circular container (shear box)
and shearing is applied by linear displacement of one half of the shear box relative to the other
Note 1 to entry: See Figure 1.
3.3
ring shear test
direct shear test (3.1) whereby an annular specimen is subjected to shear induced by rotation of one
half of the specimen relative to the other while subjected to vertical stress applied normal to the failure
(3.4) plane
Note 1 to entry: See Figures 2 and 3.
3.4
failure
stress or strain condition at which either peak horizontal shear stress is achieved or a specified
deformation criterion is achieved, if a peak horizontal shear stress is not observed
3.5
pore pressure
pressure of water in the voids within the soil specimen
3.6
primary consolidation
process whereby the void ratio of a specimen decreases as a result of an increase in the effective stress
due to a decrease in the excess pore pressure (3.5) under a constant total applied load
Note 1 to entry: Time-dependent volume change during primary consolidation is primarily controlled by
drainage conditions.
4 Symbols
D outer diameter of specimen container rings
a
D inner diameter of specimen container rings
i
D mean diameter of specimen container rings
m
R inner radius of the container rings
i
R outer radius of the container rings
a
H height of annulus in the specimen container rings or shear box
t time value from vertical displacement versus root time plot
c
t calculated minimum time to failure during shear stage
f
v maximum allowable rate of shear displacement
max
s horizontal shear deformation during ring shear
rs
s estimated horizontal shear deformation at failure
f
r mean radius of the specimen in the ring shear test
θ angular displacement during the ring shear test
θ maximum rate of angular displacement in the ring shear test
max
ρ initial bulk density of specimen
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SIST EN ISO 17892-10:2019
ISO 17892-10:2018(E)
ρ initial dry density of specimen
d
ρ particle density
s
H initial height of the specimen
0
w initial water content
0
m initial mass of specimen
0
m final dry mass of specimen
d
e void ratio
e initial void ratio
0
S initial degree of saturation
r
ρ water density
w
ΔH change in specimen height from the initial zero reading
τ shear stress on the surface of shear
τ residual shear strength
R
σ vertical stress on the surface of shear
v
P horizontal shear force
N vertical force
φ′ angle of effective shearing resistance
φ′ residual angle of effective shearing resistance
R
c′ effective cohesion intercept
A initial plan area of specimen
M moment (torque) applied to the specimen in the ring shear
t
5 Apparatus
5.1 General
The equipment shall undergo regular calibration, maintenance and checks as specified in Annex A.
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ISO 17892-10:2018(E)
5.2 Shear devices
5.2.1 Shearbox test apparatus
5.2.1.1 A typical shearbox apparatus is shown schematically in Figure 1.
Key
1 (device to apply) vertical force, N
2 loading cap to apply vertical force
3 porous discs or shear friction plates
4 upper and lower part of the shear box
5 soil specimen
6 outer container (carriage)
7 device to apply (a constant rate of) horizontal displacement
8 device for measurement of horizontal displacement
9 device for measurement of horizontal force
10 device for measurement of vertical displacement
11 gap between upper and lower parts of shear box to prevent friction
Figure 1 — Schematic drawing of a typical shearbox
5.2.1.2 The frame, the outer container (carriage), the shearbox and internal components shall be made
of corrosion resistant materials of sufficient rigidity to resist distortion and deformation during the test.
5.2.1.3 The outer container (carriage) should allow testing to be carried out with the specimen and
porous discs or shear friction plates submerged under water.
5.2.1.4 The outer container (carriage) shall be supported on the frame by a low-friction bearing which
allows movement in the horizontal direction only.
5.2.1.5 The shear box shall be square or circular in plan and divided horizontally into two rigid halves.
The design of the shear box shall fulfil the following requirements:
— The design shall allow the two halves of the shear box to be locked securely together. Once locked
together they shall form a square or circular prism with a smooth internal surface.
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SIST EN ISO 17892-10:2019
ISO 17892-10:2018(E)
— The design shall allow the upper half to be lifted relative to the lower half prior to shear by a small,
controlled vertical displacement without tilt.
— The arrangement shall be such that when lifted, one half of the shear box shall be able to move
smoothly and parallel to the other half.
— The square shear box should be designed for a square specimen with a minimum width of 50 mm.
The circular shear box should be designed for a specimen with a minimum diameter of 50 mm.
— In both cases the shear box should be designed for a specimen with a minimum initial height of
20 mm or not less than 6 times the maximum particle size diameter, whichever is larger.
— The ratio of the specimen width or diameter to height should not be less than 2,5.
5.2.1.6 Porous discs or shear friction plates shall cover the upper and lower surfaces of the specimen:
— They shall allow free drainage of water, while preventing intrusion of soil particles into their pores.
The upper and lower surfaces shall be plane, clean and undamaged. They shall be made of corrosion-
resistant materials of negligible compressibility under the maximum stress likely to be applied
during the test and shall be strong enough to prevent breakage under load.
— They should be sufficiently rough to provide an interlock with the sample but without causing
localised stress concentrations.
— They shall be smaller in plan than the internal dimensions of the shear box in order to prevent
binding to the walls but large enough to prevent extrusion of the specimen.
5.2.1.7 The loading cap shall be smaller in plan than the internal dimensions of the shear box such that
the loading cap can tilt without jamming
...
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