SIST-TS CEN ISO/TS 17892-5:2004
(Main)Geotechnical investigation and testing - Laboratory testing of soil - Part 5: Incremental loading oedometer test (ISO/TS 17892-5:2004)
Geotechnical investigation and testing - Laboratory testing of soil - Part 5: Incremental loading oedometer test (ISO/TS 17892-5:2004)
This document is intended for determination of the compression, swelling and consolidation properties of soils. The cylindrical test specimen is confined laterally, is subjected to discrete increments of vertical axial loading or unloading and is allowed to drain axially from the top and bottom surfaces.
The main parameters derived from the oedometer test relate to the compressibility and rate of primary consolidation of the soil. Estimates of preconsolidation pressure, rate of secondary compression, and swelling characteristics are sometimes also obtainable.
The main parameters which can be derived from the oedometer test carried out on undisturbed samples are:
1) compressibility parameters;
2) coefficient of consolidation;
3) apparent preconsolidation pressure or yield stress;
4) coefficient of secondary compression;
5) swelling parameters.
The fundamentals of the incremental loading oedometer test include:
- stress path corresponds to one dimensional straining;
- drainage is one-dimensional and axial.
The stress paths and drainage conditions in foundations are generally three dimensional and differences can occur in the calculated values of both the magnitude and the rate of settlement.
The small size of the specimen generally does not adequately represent the fabric features present in natural soils.
Analysis of consolidation tests is generally based on the assumption that the soil is saturated. In case of unsaturated soils, some of the derived parameters may have no physical meaning.
Geotechnische Erkundung und Untersuchung - Laborversuche an Bodenproben - Teil 5: Oedometerversuch mit stufenweiser Belastung (ISO/TS 17892-5:2004)
Reconnaissance et essais géotechniques - Essais de laboratoire sur les sols - Partie 5: Essai de chargement par paliers a l'oedometre (ISO/TS 17892-5:2004)
L'ISO 17892-5:2004 a pour objet la détermination des propriétés de consolidation, de gonflement et de consolidation des sols. L'éprouvette d'essai cylindrique est confinée latéralement et soumise à un chargement ou déchargement vertical et axial par paliers, tout en étant drainée axialement par le haut et par le bas.
Les principaux paramètres déduits de l'essai oedométrique fournissent la compressibilité et le taux de consolidation primaire du sol. Des estimations de la contrainte de préconsolidation, du coefficient de consolidation secondaire et des paramètres de gonflement sont également parfois possibles.
Les principaux paramètres pouvant être déduits de l'essai oedométrique réalisé sur des échantillons non remaniés sont:
1) les paramètres de compressibilité;
2) le coefficient de consolidation;
3) la contrainte apparente de préconsolidation ou la résistance du matériau;
4) le coefficient de consolidation secondaire;
5) les paramètres de gonflement.
Les principes de l'essai oedométrique à chargement par paliers sont les suivants: le chemin de contraintes correspond à une déformation unidimensionnelle, le drainage est axial et unidimensionnel.
Les chemins de contraintes et les conditions de drainage sous des fondations sont généralement tridimensionnels et des différences peuvent apparaître au niveau des valeurs calculées pour le tassement ou pour sa vitesse.
La petite dimension de l'éprouvette ne permet généralement pas de représenter correctement les hétérogénéités présentes dans les sols naturels.
L'analyse d'un essai de consolidation repose généralement sur l'hypothèse que le sol est saturé. Dans le cas de sols non saturés, certains paramètres déduits de l'essai peuvent ne pas avoir de signification physique.
Geotehnično preiskovanje in preskušanje – Laboratorijsko preskušanje zemljin – 5. del: Edometrski preskus s postopnim obremenjevanjem (ISO/TS 17892-5:2004)
Ta dokument je namenjen ugotavljanju stisljivosti, nabrekljivosti in konsolidacije zemljin. Vzorec za preskus z valjem je bočno omejen, obremenjevanje ali razbremenjevanje poteka postopoma z navpične osi, drenaža pa poteka osno z vrhnje in spodnje površine. Glavni parametri, pridobljeni z edometrskim preskusom, so povezani s stisljivostjo in hitrostjo primarne konsolidacije zemljine. Včasih se lahko pridobijo tudi ocene predkonsolidacijskega tlaka, hitrosti sekundarne stisljivosti in značilnosti nabrekanja. Glavni parametri, ki se lahko pridobijo iz edometrskega preskusa, opravljenega na nespremenjenih vzorcih, so: 1) parametri stisljivosti; 2) koeficient konsolidacije 3) navidezni predkonsolidacijski tlak ali napetost tečenja; 4) koeficient sekundarne stisljivosti; 5) parametri nabrekanja. Osnove edometrskega preskusa s postopnim obremenjevanjem vključujejo naslednje: - napetostna pot ustreza enodimenzionalni deformaciji; - drenaža je enodimenzionalna in osna. Napetostne poti in pogoji drenaže v podlagah so ponavadi tridimenzionalni, zato lahko prihaja do razlik pri izračunanih vrednostih v obsegu in hitrosti posedanja. Majhna velikost vzorca ponavadi ne predstavlja primerno lastnosti materiala v naravnih zemljinah. Analiza konsolidacijskih preskusov v splošnem temelji na domnevi, da je zemljina zasičena. V primeru nezasičenih zemljin nekateri dobljeni parametri morda nimajo fizikalnega pomena.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST-TS CEN ISO/TS 17892-5:2004
01-december-2004
*HRWHKQLþQRSUHLVNRYDQMHLQSUHVNXãDQMH±/DERUDWRULMVNRSUHVNXãDQMH]HPOMLQ±
GHO (GRPHWUVNLSUHVNXVVSRVWRSQLPREUHPHQMHYDQMHP ,6276
Geotechnical investigation and testing - Laboratory testing of soil - Part 5: Incremental
loading oedometer test (ISO/TS 17892-5:2004)
Geotechnische Erkundung und Untersuchung - Laborversuche an Bodenproben - Teil 5:
Oedometerversuch mit stufenweiser Belastung (ISO/TS 17892-5:2004)
Reconnaissance et essais géotechniques - Essais de laboratoire sur les sols - Partie 5:
Essai de chargement par paliers a l'oedometre (ISO/TS 17892-5:2004)
Ta slovenski standard je istoveten z: CEN ISO/TS 17892-5:2004
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-TS CEN ISO/TS 17892-5:2004 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST-TS CEN ISO/TS 17892-5:2004
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SIST-TS CEN ISO/TS 17892-5:2004
TECHNICAL SPECIFICATION
CEN ISO/TS 17892-5
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
October 2004
ICS 13.080.20; 93.020
English version
Geotechnical investigation and testing - Laboratory testing of
soil - Part 5: Incremental loading oedometer test (ISO/TS 17892-
5:2004)
Reconnaissance et essais géotechniques - Essais de sol Geotechnische Erkundung und Untersuchung -
au laboratoire - Partie 5: Essai à l'oedomètre sur sol saturé Laborversuche an Bodenproben - Teil 5:
(ISO/TS 17892-5:2004) Oedometerversuch mit stufenweiser Belastung (ISO/TS
17892-5:2004)
This Technical Specification (CEN/TS) was approved by CEN on 2 December 2003 for provisional application.
The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit their
comments, particularly on the question whether the CEN/TS can be converted into a European Standard.
CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS available
promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the CEN/TS)
until the final decision about the possible conversion of the CEN/TS into an EN is reached.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2004 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN ISO/TS 17892-5:2004: E
worldwide for CEN national Members.
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Contents
Foreword.4
1 Scope .6
2 Normative references .6
3 Terms and definitions .7
4 Symbols .7
5 Equipment .8
5.1 Requirements.8
5.2 Calibration .11
5.3 Environment.12
6 Test procedure.12
6.1 General requirements.12
6.2 Specimen preparation .12
6.3 Measurement and protection.13
7 Test results.17
7.1 General.17
7.2 Initial values .17
7.3 Compressibility characteristics .18
8 Test report .19
8.1 Mandatory reporting.19
8.2 Optional reporting.19
Annex A (informative) Additional calculations.21
A.1 Additional symbols.21
A.2 Soil condition .22
A.3 Compressibility parameters .22
A.4 Swelling parameters.24
Bibliography .30
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Figures
Figure 1 — General arrangements of typical oedometer cells .9
Figure 2 — Typical plot of void ratio against vertical effective stress.16
Figure A.1 — Change of effective stress and vertical strain for incremental loading and unloading.23
Figure A.2 — Change of effective stress and void ratio for incremental loading and unloading.23
Figure A.3 — Laboratory consolidation curve: example of log time fitting method .25
Figure A.4 — Laboratory consolidation curve: example of square root of time fitting method .26
Figure A.5 — Temperature correction curve for coefficient of consolidation .27
Figure A.6 — Derivation of coefficient of secondary compression C .28
αα
αα
Figure A.7 — Determination of the apparent preconsolidation pressure σσ' .29
σσ
p
Tables
Table 1 — Suggested initial pressure.14
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Foreword
This document (CEN ISO/TS 17892-5:2004) has been prepared by Technical Committee CEN/TC 341
“Geotechnical investigation and testing”, the secretariat of which is held by DIN, in collaboration with Technical
Committee ISO/TC 182 “Geotechnics”.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to announce this Technical Specification: Austria, Belgium, Cyprus, Czech Republic, Denmark,
Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
CEN ISO/TS 17892 consists of the following parts, under the general title Geotechnical investigation and testing —
Laboratory testing of soil:
Part 1: Determination of water content
Part 2: Determination of density of fine grained soil
Part 3: Determination of particle density - Pycnometer method
Part 4: Determination of particle size distribution
Part 5: Incremental loading oedometer test
Part 6: Fall cone test
Part 7: Unconfined compression test on fine grain soils
Part 8: Unconsolidated undrained triaxial test
Part 9: Consolidated triaxial compression tests on water saturated soils
Part 10: Direct shear tests
Part 11: Determination of permeability by constant and falling head
Part 12: Determination of the Atterberg limits
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Introduction
This document covers areas in the international field of geotechnical engineering never previously standardised. It
is intended that this document presents broad good practice throughout the world and significant differences with
national documents is not anticipated. It is based on international practice (see [1]).
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1 Scope
This document is intended for determination of the compression, swelling and consolidation properties of soils. The
cylindrical test specimen is confined laterally, is subjected to discrete increments of vertical axial loading or
unloading and is allowed to drain axially from the top and bottom surfaces.
The main parameters derived from the oedometer test relate to the compressibility and rate of primary
consolidation of the soil. Estimates of preconsolidation pressure, rate of secondary compression, and swelling
characteristics are sometimes also obtainable.
The main parameters which can be derived from the oedometer test carried out on undisturbed samples are:
1) compressibility parameters;
2) coefficient of consolidation;
3) apparent preconsolidation pressure or yield stress;
4) coefficient of secondary compression;
5) swelling parameters.
The fundamentals of the incremental loading oedometer test include:
stress path corresponds to one-dimensional straining;
drainage is one-dimensional and axial.
The stress paths and drainage conditions in foundations are generally three dimensional and differences can occur
in the calculated values of both the magnitude and the rate of settlement.
The small size of the specimen generally does not adequately represent the fabric features present in natural soils.
Analysis of consolidation tests is generally based on the assumption that the soil is saturated. In case of
unsaturated soils, some of the derived parameters may have no physical meaning.
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 any
amendments) applies.
prEN 1997-2, Eurocode 7 - Geotechnical design — Part 2: Ground investigation and testing.
CEN ISO/TS 17892-1, Geotechnical investigation and testing — Laboratory testing of soil — Part 1: Determination
of water content (ISO/TS 17892-1:2004).
CEN ISO/TS 17892-2, Geotechnical investigation and testing — Laboratory testing of soil — Part 2: Determination
of density of fine grained soil (ISO/TS 17892-2:2004).
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3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
excess pore pressure
pore water pressure over and above the equilibrium pore pressure at the end of consolidation
3.2
primary consolidation
process whereby soil compresses as a result of an increase (or decrease) in effective stress due to dissipation of
excess pore pressure under constant total applied stress accompanied by drainage of water from the voids
3.3
secondary consolidation
process in which compression occurs after full excess pore pressure dissipation
3.4
swelling
expansion due to reduction of effective stress
NOTE Swelling includes both the reverse of compression and the reverse of consolidation.
3.5
undisturbed sample
normally a sample of quality class 1 according to prEN 1997-2
4 Symbols
For the purposes of this document, the following symbols apply.
A Cross-sectional area of specimen.
e Void ratio, i.e. volume of pores relative to volume of solid particles.
e Original void ratio, i.e. void ratio of the specimen at the start of the test.
0
e Void ratio of the specimen at the end of an increment: this is the void ratio of the specimen at the start of the
f
next increment.
D Diameter of the oedometer ring.
H Height of the specimen.
H Original height, i.e. height of the specimen at the start of the test: this is normally taken as the depth of the
0
oedometer ring.
H Initial height, i.e. height of the specimen at the start of an increment: this is the height of the specimen at the
i
end of the previous increment.
H Height of the specimen at the end of an increment: this is the height of the specimen at the start of the next
f
increment.
H Equivalent height of solids.
s
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m Dry mass of specimen.
d
ε Vertical strain.
v
ρ Initial density of specimen.
ρ Initial dry density of specimen.
d
ρ Particle density.
s
σ´ Swelling pressure, i.e. the pressure required to maintain constant volume (i.e. to prevent swelling) when a soil
s
is flooded with water.
σ Total vertical stress, i.e. the vertically applied force divided by the horizontal cross-sectional area.
v
σ´ Effective vertical stress, i.e. the difference between the total vertical stress and the pore water pressure.
v
5 Equipment
5.1 Requirements
5.1.1 Oedometer ring
5.1.1.1 The oedometer ring shall be indelibly marked with a unique identification number. The cutting edge
shall not be damaged.
5.1.1.2 The internal dimensions shall conform to the following:
diameter: minimum 35 mm;
height (H): not less than 12 mm;
ratio (D/H): not less than 2,5.
5.1.1.3 The ring shall either be laterally confined to restrict expansion under load, or have sufficient stiffness to
prevent the internal diameter expanding by more than 0,05 % when subjected to the maximum horizontal stress
resulting from the test.
5.1.1.4 The ring shall be made of corrosion-resistant metal or other suitable material and shall have a sharp
cutting edge. The internal surface shall be smooth, and shall be lubricated with a thin film of silicone grease,
petroleum jelly, or other suitable lubricant.
5.1.2 Porous plates
5.1.2.1 The top and bottom porous plates shall be of corrosion-resistant material and 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. The material shall be of negligible compressibility under the maximum stress likely to be
applied during the test and shall be thick enough to prevent breakage under load.
5.1.2.2 If necessary, a filter paper may be used to prevent intrusion of the soil into the porous stones.
However, the permeability of the stones and the filter paper shall be sufficiently high to prevent retardation of the
drainage of the specimen.
5.1.2.3 The diameter of the top porous plate shall be about 0,5 mm less than the internal diameter of the
oedometer ring, and may be tapered towards the upper face to minimize the risk of binding due to tilt.
5.1.2.4 In a fixed-ring cell the bottom porous plate shall be large enough to support the oedometer ring.
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5.1.2.5 In a floating-ring cell the diameter of the bottom porous plate shall be about 0,5 mm less than the
internal diameter of the ring. The bottom porous plate shall be similar to the top plate, but tapered towards the
lower face (see Figure 1).
Key
a) Fixed ring oedometer
b) Floating ring oedometer
1 Seating
2 Loading cap
3 Lateral restraint for ring
4 Cell body
5 Porous plates
6 Oedometer ring
Figure 1 — General arrangements of typical oedometer cells
5.1.2.6 Before use, new porous plates shall be saturated by boiling in distilled or de-ionised water for at least
20 min. They shall then be kept immersed in distilled water until required for use.
5.1.2.7 The surface of the porous plates which have previously been used shall be cleaned with a natural
bristle or nylon brush, followed by a check that the plates are readily permeable to water and that the pores are not
clogged by soil particles. They shall then be saturated by boiling as described above.
In soft soils the difference between the diameter of the porous plate and the internal diameter of the ring may need
to be reduced to 0,2 mm to avoid extrusion of soil.
5.1.3 Cell body
5.1.3.1 The cell body shall be of suitable corrosion-resistant metal or other suitable material.
5.1.3.2 A fixed-ring cell (see Figure 1a) shall accept the oedometer ring with a push fit and shall be rigid
enough to prevent significant lateral deformation of the ring when under load.
5.1.3.3 A floating-ring cell (see Figure 1b) shall provide adequate clearance around the outside of the ring.
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5.1.3.4 The assembled cell (see Figure 1) shall be watertight and shall hold water to a level which submerges
the upper porous plate.
5.1.3.5 All components shall be made of materials which are not corrodible by electro-chemical reaction with
each other, or the soil and the pore water.
5.1.4 Loading cap
5.1.4.1 The loading cap shall be rigid enough to ensure negligible deformation under load.
5.1.4.2 It shall be fitted with a central load seating and shall be mounted centrally in the consolidation cell.
5.1.4.3 If porous disks with a thickness of less than 6 mm are used, then the loading cap shall have
perforations or grooves to allow the free drainage of pore water.
5.1.5 Deformation gauge
5.1.5.1 The deformation gauge may be either a dial gauge or an electrical displacement transducer, rigidly
supported for measuring the vertical deformation of the specimen during the test.
5.1.5.2 The gauge shall have a travel of at least 10 mm with a resolution and accuracy of 0,002 mm. When a
travel exceeding 10 mm is required (e.g. for highly compressible soil) an accuracy and resolution of 0,01 mm is
acceptable.
If non-conventional equipment is used the reference system used for the measurements should be clearly defined
in order to clarify which components of the apparatus contribute to the compliance of the measuring system.
5.1.6 Loading frame
5.1.6.1 The loading frame shall have a rigid bed on which the cell body is supported.
5.1.6.2 The loading frame shall allow the application of vertical stresses acting centrally on the loading cap
only.
5.1.6.3 The vertical stress applied to the specimen shall be accurate to better than 1 % or 1 kPa. The stress
shall remain constant within these limits throughout the duration of a loading increment. The mechanism shall allow
the application of a given load increment within a period of 2 s without significant impact.
5.1.6.4 Adequate arrangements shall be made to ensure stability of the load frame, or a group of load frames,
when fully loaded.
5.1.7 Ancillary apparatus
The ancillary apparatus consists of:
balance, accuracy 0,03 g, readable to 0,01 g or better;
timer readable to 1 s;
maximum/minimum thermometer readable to 1 °C;
metal disk with flat, smooth and parallel end faces. The diameter shall be about 1 mm less than the internal
diameter of the oedometer ring and the height shall be the same as that of the ring;
apparatus for determination of water content;
apparatus for determination of particle density;
vernier callipers reading to 0,05 mm.
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5.1.8 Apparatus for specimen preparation
The apparatus for the specimen preparation consists of:
cutting and trimming tools (e.g. cheese-wire, wire-saw, sharp knife, scalpel);
spatulas;
straight-edge trimmer;
reference straight-edge (e.g. engineer's steel rule);
steel try-square;
flat glass plate;
extrusion equipment and clamping jig (for preparing and trimming specimens from a tube sample).
5.1.9 Water
The water added to the cell to submerge the sample shall not influence the test results. For marine clays and for
soils from off-shore sites sea-water should be used.
Normally ground water from the site at which the sample was taken, or similar natural or prepared water shall be
used if distilled water is likely to influence the test results. Soils from certain regions may require water with salinity
even higher than that of normal sea-water.
5.2 Calibration
5.2.1 Oedometer ring
5.2.1.1 The internal diameter of the oedometer ring shall be measured in two perpendicular directions to the
2
nearest 0,05 mm. The mean diameter D (mm) and the area A (mm ) shall be calculated.
5.2.1.2 The height of the ring at four equally spaced points shall be measured to the nearest 0,05 mm. The
mean height H (mm) and the contained volume V (ml) shall be calculated.
0 0
5.2.1.3 The ring shall be weighed to the nearest 0,01 g.
5.2.2 Deformation of apparatus
5.2.2.1 The oedometer apparatus shall be assembled by using the metal disc in place of the specimen. The
porous stones shall be moistened. If filter papers are to be used during the actual test, they should be moistened
during calibration and sufficient time should be allowed during the calibration process for the water to be squeezed
from them.
5.2.2.2 Increments of load shall be applied similar to those applied in a test and the reading of the deformation
gauge corresponding to each increment shall be recorded. It is advisable, before a calibration loading test, first to
load and unload the metal disc without taking any reading in order to avoid small movements, strains, inequalities
etc., and then start the calibration loading as above.
5.2.2.3 Unloading shall be performed in similar decrements and the deformation shall be recorded.
5.2.2.4 The deformations shall be tabulated as cumulative deformations against the applied loads or plotted as
a graph of cumulative deformation against the applied load. In the calibration report it should be clearly noted
whether filter papers were used during the calibration process and, if so, what type of filter paper was used.
5.2.2.5 Re-calibration of the equipment is necessary at regular intervals (at least once a year) and when
essential parts are changed or replaced.
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5.2.2.6 The appropriate value of the apparatus deformation is deducted from the measured deformation in a
test to give the cumulative deformation of the specimen itself under the given load. This correction is likely to be
significant only for relatively stiff soils.
5.2.2.7 In extremely stiff soils, tested at high stress levels, the lateral deformability of the ring may also affect
the results. To avoid lateral deformation of the specimen, special very stiff oedometer rings should be used.
5.3 Environment
5.3.1 Test specimens shall be prepared in an environment which avoids significant loss or gain of soil water. If
the preparation process is interrupted the specimen shall be protected by wrapping in thin plastic sheet or clingfilm.
5.3.2 The area in which the test is carried out shall be free from significant vibrations and mechanical
disturbance. The apparatus shall be protected against sunlight, local sources of heat and draughts.
5.3.3 The temperature of the test location shall be maintained constant to within ± 2 °C. Maximum and minimum
temperatures shall be recorded daily.
6 Test procedure
6.1 General requirements
6.1.1 This test is applicable to saturated homogeneous specimens. The test should be carried out on
undisturbed samples.
6.1.2 The mean diameter of the largest particle within a specimen shall not normally exceed one-fifth of the
height of the ring.
6.2 Specimen preparation
6.2.1 Selection of preparation method
Test specimens may be prepared by the following methods depending on the type of sample available:
extrusion from a sample tube of the same diameter as the oedometer ring (when trimming would cause
significant disturbance);
extrusion from a sample tube of a diameter larger than that of the ring (homogeneous soils with few coarse
particles or other features likely to cause disturbance);
trimming from an undisturbed block sample (taken by hand or removed from a tube);
trimming from an undisturbed sample obtained by continuous sampling methods;
artificial compaction of disturbed soil (when undisturbed samples cannot be obtained).
6.2.2 Extrusion from tube of diameter equal to ring
6.2.2.1 The sampling tube shall be mounted in the extrusion device and the oedometer ring shall be securely
clamped in position with its axis in line with the axis of the tube.
6.2.2.2 Any disturbed soil shall be extruded from the end of the tube and the surface of the soil remaining in
the tube shall be trimmed flat.
6.2.2.3 The sample shall be extruded until the ring is filled, with some excess soil at either end. The direction
of extrusion shall be recorded.
6.2.2.4 The extruded soil shall be cut off with a wire saw.
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6.2.2.5 Portions of the soil trimmings shall be used for a preliminary determination of water content, a test for
particle density and other classification properties, if required (see note).
6.2.2.6 Each end of the specimen shall be trimmed in turn, using a sharp knife or scalpel to cut away excess
soil a little at a time. The ends shall be checked to be flat and flush with each edge of ring. Leaving smeared
surfaces shall be avoided.
NOTE The water content determined at this stage enables preliminary values of void ratio to be calculated while the test
proceeds, before the final dry mass is available.
6.2.3 Extrusion from tube of larger diameter
6.2.3.1 The procedure described in 6.2.2 shall be followed. Additionally, it should be checked that excess soil that
is cut off by the ring can be removed easily and does not impede the extrusion process.
6.2.4 Trimming from block sample or continuous sample
6.2.4.1 A horizontal flat surface shall be prepared on the sample of a size larger than the diameter of the
oedometer ring.
6.2.4.2 The sample shall be placed on to the trimming apparatus, the ring shall be fitted into its holder and the
cutting edge shall be lowered on to the prepared surface.
6.2.4.3 The ring shall be steadily forced into the sample until it is filled with soil with an excess protruding from
the top. Soil cuttings shall be removed so that advance of the ring is not impeded.
6.2.4.4 With stiff soils the sample shall be trimmed in advance of the ring to about 1 mm or 2 mm larger than
the internal ring diameter so that the cutting edge removes the remaining thin layer.
6.2.4.5 The sample shall be cut off underneath the ring to remove the ring and contained soil.
6.2.4.6 Soil trimmings shall be used and the trimming of the specimen shall be completed, as described in
6.2.2.5 and 6.2.2.6.
6.2.5 Recompacted specimens
6.2.5.1 Disturbed samples shall be prepared by compacting the soil into a suitable mould
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