JGS 0550-2020

Japanese Geotechnical Society Standard (JGS 0550-2020)
Practice for preparing hollow cylindrical specimens of soils for torsional
shear test
1

Scope

This standard specifies a method of preparation of specimens for tests carried out in accordance with the seriesof torsional shear tests on soils. The standard applies to cohesive soils and sandy soils.
Note:

2

This standard can also be applied to other geomaterials.

Normative references

The following standards shall constitute a part of this standard by virtue of being referenced in this standard.
The latest versions of these standards shall apply (including supplements).
JIS A 0207
JIS A 1202
JIS A 1203
JIS A 1205
JIS A 1224
JGS 0051
JGS 0102
JGS 0122
JGS 0142
JGS 0520

Technical terms for geotechnical engineering
Test method for density of soil particles
Test method for water content of soils
Test method for liquid limit and plastic limit of soils
Test method for minimum and maximum densities of sands
Method of classification of geomaterials for engineering purposes
Practice for handling undisturbed samples for laboratory testing to determine mechanicalproperties of cohesive soils
Test method for water content of soils by the microwave oven
Test method for liquid limit of soils by the fall cone
Preparation of soil specimens for triaxial tests

The series of torsional shear test methods refers to the following standards.
JGS 0543
JGS 0551

Method for cyclic torsional shear test on hollow cylindrical specimens to determine deformation
properties of soils
Method for torsional shear test on hollow cylindrical specimens of soils

3

Equipment

3.1

Test specimen preparation equipment

In the case of the trimming method, a) to c) shall be used, and in the case of the negative pressure method, d)and e) shall be used for preparing a specimen.
Note:

Frozen and other samples may be shaped using a core cutter, disc cutter, drill or other tools as needed.

a)Trimmerb)

Miter box
In general, the miter box should be in two parts and have an inner diameter about same as the external
diameter of the specimen. The two end faces shall be parallel to each other, and also perpendicular to theaxis of the inserted specimen. The miter box shall have at its both ends extension collars having a holewith a diameter equal to the internal diameter of the specimen.

© JGS 2018 – All rights reserved

1

JGS 0550-2020

c)

Wire saw and straight knife
The diameter of the steel wire used for the wire saw shall be about 0.2-0.3 mm. The straight edge shall bemade of steel and single-edged.

d)External and internal molds
In general, the external mold should be separated into multiple parts. The hollow part height whenassembled on the pedestal shall be equal to the height of the specimen, and the internal diameter shall begreater than the external diameter of the specimen by twice the thickness of the rubber sleeve. The externalmold shall have suction pores on its inner surface to ensure that the rubber sleeve comes into close contact
with the inner surface of the mold.
In general, the internal mold should be separated into multiple parts and have a height greater than the
combined height of the specimen and cap. Its external diameter shall be smaller than the internal diameterof the specimen by twice the thickness of the rubber sleeve.

e)Equipment for supplying samples and equipment for compacting samples
The equipment below shall be prepared according to the specimen preparation methods, as needed.

Note:
1)

Air-pluviation method or water-pluviation method: Funnel, nozzle, nested sieves, etc.

2)Compaction method: Ramming rod, disk plate for compacting, plastic or wooden hammer, vibrator, etc.

3.2

Other equipment

The equipment used for preparing and installing the specimens shall conform to the following requirements.
Note:

a)

When necessary an O-ring expander, rubber sleeve expander, and filter are used.

Negative pressure generator
The negative pressure generator shall be capable of applying negative pressure to ensure close contact
between the external rubber sleeve and the internal surface of the external mold, and, when preparing
specimens using the negative pressure method, it is also used to make support the specimen to keep its
shape.

b)

Rubber sleeve
The thickness of the rubber sleeve in its natural state shall be between 0.15 and 0.3 mm, and the internal
diameter of the rubber sleeve shall be about 95% of the external diameter or the internal diameter of thespecimen.

c)O-ring or rubber band
The O-ring internal diameter shall be about 80% of the diameter of the part that is tightened, and thetightening force shall be sufficient to prevent leakage.

d)Instrument for measuring specimen size
The instrument used to measure the specimen size shall be capable of determining the external diameter,internal diameter, and height of the specimen to a precision of 0.05 mm or better. A caliper or a steel
measuring tape with a vernier scale (Pi Tape) shall be used for measurement of the external diameter ofthe specimen. Also, a caliper or similar shall be used for measuring the internal diameter.

e)

Weighing scale
The weighing scale shall have a precision of 0.01 g or better.

2© JGS 2018 – All rights reserved

JGS 0550-2020

4

Test specimen preparation and installation method

4.1

Types and selection of the test specimen preparation method

Two methods of preparing specimens are available, as follows:a)Trimming method
The trimming method shall be used for samples that are stable and in large pieces, either at room
temperature or frozen, including those collected by block sampling or certain types of samplers, those
prepared by pre-consolidation or compaction, and those that are frozen.

b)

Negative pressure method
The negative pressure method shall be used for samples obtained in a loosened state that cannot be
formed into large pieces by compaction and consolidation.

4.2

Shape and dimensions of test specimens

The shape and dimensions of the specimens shall be as follows.
a)

The specimen shall have a hollow cylindrical shape.

b)

The standard external diameter of the specimen shall be 70 mm or more for sandy soils, 50 mm or more
for cohesive soils. The standard internal diameter shall be 30 mm or more for sandy soils, and 20 mm ormore for cohesive soils.

c)

The standard height of the specimen shall be between 1 and 2 times the external diameter as standard.

d)The standard thickness of the specimen shall be at least 10 times the maximum particle size in the test
sample.

Note:

The thickness of the specimen may be up to 5 times the maximum particle size of a sample for soils having a wide

range of particle sizes.

4.3

Preparation and measurement of specimens by the trimming method

Following the procedures listed in a) through h), specimens must be prepared with care so as to avoid changes
in sample water content. Particular care must be exercised to avoid disturbing the sample. Before molding
frozen samples, cool the specimen preparation equipment. During molding and when measuring the dimensionsof the specimen, the work must be performed quickly so as to avoid melting of the sample.
a)

Any soil material that is deemed to have been disturbed in the sampling process, etc. must be removed
from the sample before preparing specimens. In principle, the sample is to be greater than the specimen
in diameter and height by a sufficient margin.

b)

The side surface of the specimen shall be shaped using a trimmer, wire saw, straight edge, or similar togive it a cylindrical shape with the specified diameter. When shaping is performed using a trimmer, careshall be paid not to apply torque and /or compression force to the specimen. Specimen preparation isusually conducted by scraping the sample with a wire saw, while a straight edge may be used when thespecimen is stiff.

Note:

If the sample might be overly disturbed by shaping the sides, it is permissible to omit the shaping of the sides of asample extracted from a sample tube.

c)

The specimen is shaped using a miter box, wire saw, straight edge, or similar, so that the two end faces ofthe specimen become parallel to each other and perpendicular to the specimen axis.

d)

The hollow part of the specimen shall be formed to a hollow cylinder of the prescribed internal diameterusing a miter box, wire saw, straight edge, etc. The hollow part of the specimen is formed by installing© JGS 2018 – All rights reserved

3

JGS 0550-2020

extension collars having a central hole of the same size as the specified internal diameter of the specimen
onto the miter box.
e)Measure the external diameter and the internal diameter of the specimen in two orthogonal directions witha precision of 0.1% or better, at upper, middle and lower positions of the specimen. Take the mean valueof the three measurements as the initial external diameter Doi (mm) and the initial internal diameter Dii (mm)of the specimen. When the above precision is smaller than that of the measuring device to be used, theprecision shall be set at 0.05mm. The allowable difference between the measured values shall be within±1% of Doi and Dii.

f)Measure the height of the specimen with a precision of 0.1% or better, at three or more points that areassigned by dividing evenly the circumference of the specimen. Take the mean value of the threemeasurements as the initial height Hi (cm) of the specimen. The allowable difference between themeasured values shall be within ±0.5% of Hi.

g)

The mass of the specimen mi (g) shall be measured with a precision of 0.1% or better.

Note:

Use the following equations to obtain the wet density ρti (Mg/m3), dry density ρdi (Mg/m3), void ratio ei, degree ofsaturation Sri (%), and relative density Dri (%) of the specimen in the initial state, as needed.

ρti =

mi
× 1000
Vi

ρdi =

ms
× 1000Viei =Vi ρs /1000
−1
ms

Sri =

ρ
mi − ms× s × 100Vi ρs /1000 − ms ρw

Dri =emax − ei
× 100emax − emin

where
Vi:
ρs:
ρ w:
ms:
emax:
emin:

Initial volume of the specimen (mm3) (Vi = π(D2oi − D2ii )Hi /4)
Density of the soil particle (Mg/m3)
Density of water (Mg/m3)
Oven-dried mass of specimen (g)Void ratio of specimen by minimum density test
Void ratio of specimen by maximum density testh)A representative sample of the specimen shall be taken from the soil removed when forming the specimen,
for which the water content shall be measured to obtain the initial water content of the specimen wi (%).

4.4

Producing and measuring the test specimens by the negative pressure method

When using the negative pressure method, specimens shall be prepared and measured as follows. Figure 1
shows a specimen in the process of preparation by the negative pressure method.
a)4

Assemble the pedestal, the rubber sleeves, and the internal and external molds by the prescribed method.
The rubber sleeves shall be fitted in close contact to the internal surface of the external mold, and, theexternal surface of the internal mold. Check that the molds have been correctly installed. When there is arigid connection between the cap and the loading piston, check that the central axes of the cap and molds
coincide. In case of other connection types, check that the bottom plate and the top surface of the mold
© JGS 2018 – All rights reserved

JGS 0550-2020

are horizontal, using a level or similar. Apply a vacuum pressure at the sleeve-mold interface to ensure thatthe external rubber sleeve is always in close contact with the internal surface of the external mold.
b)Fill the space between the external mold and the internal mold with the sample material using one of themethods given below. When the prescribed height is reached, smooth the upper surface of the specimen.
The following methods may be used to fill the mold with sample material.

Note:

Control the water content of the sample as needed. If a saturated sample is being tested, permeate a sufficientamount of deaerated water into the sample to remove the air in advance.

1)

Air-pluviation method
Drop the dry sample into the annulus between the molds through a nozzle or nested sieves. If using
a nozzle, adjust the density of the specimen by varying the drop height between the nozzle and the
top surface of the specimen between the molds, and by the nozzle opening area. If using nested
sieves, adjust the density of the specimen by varying the diameter of the opening at the bottom of thefunnel and the drop height.

2)

Water-pluviation method
Pour a dry sample or a sample that has been stored in a sample tank with a large quantity of water
into the annulus between the molds filled with deaerated water in advance, using a nozzle or spoon.
Adjust the density of the specimen by controlling the amount of the sample poured each time or by
varying the drop height between the nozzle and the top surface of the specimen between the molds.

3)

Wet tamping method
Place the sample in the annulus between the molds in several batches using a spoon or nozzle, andcompact it each time using a ramming rod. Compaction may also be done by tapping the lower partof the mold with a hammer or agitating the mold using vibrator or by other methods.

c)Place the cap on the top of the specimen, and bring the external and internal rubber sleeves and the cap
into close contact using an O-ring or similar.

d)Apply appropriate negative pressure (typically 5-10 kN/m2) to inside the specimen, and remove the external
and internal molds. When applying the negative pressure to the specimen, vertical displacement of the cap
must not be constrained so as to ensure that the isotropic stress state of the specimen is maintained.

Note:

Measures must be taken to offset the loading applied by the cap and the loading piston as needed.

e)After increasing the negative pressure to about 20 kN/m 2, measure the external diameter and the internal
diameter of the specimen including the rubber sleeve in two orthogonal directions with a precision of 0.1%
or better at upper, middle and lower positions of the specimen. Taking the mean of the measured values,
correct for the thickness of the rubber sleeve as measured in advance and determine the initial external
diameter Doi (mm) and the initial internal diameter Dii (mm) of the specimen. When the above precision issmaller than that of the measuring device to be used, the precision shall be set at 0.05mm. The allowabledifference between the measured values shall be within ±1% of Doi and Dii. The negative pressure mustremain lower than the prescribed effective stress in the lateral direction at the termination of consolidation.

f)Measure the height of the specimen with a precision of 0.1% of the height or better at three or more points
that are assigned by dividing evenly the circumference of the specimen, and obtain the mean value todetermine the initial height Hi (mm) of the specimen. The allowable difference between measured values
shall be within ±0.5% of Hi.

g)

Determine the mass of the specimen with a precision of 0.1% of the mass or better, as the difference
between the mass of the whole original sample before forming the specimen and that of the residual amount© JGS 2018 – All rights reserved

5

JGS 0550-2020

after preparing the specimen. Alternatively, the whole sample can be collected and weighed after thetesting with a precision of 0.1% of the mass or better.
Follow the procedure given in Note of 4.3 g) to obtain the wet density ρti (Mg/m3), dry density ρdi (Mg/m3), void ratio

Note:ei, degree of saturation Sri (%), and relative density Dri (%) of the specimen in the initial state as needed.

h)Split a representative quantity from the original sample and measure the water content to determine theinitial water content wi (%) of the specimen as needed.

5

Specimen installation processes

The external pressure and the internal pressure applied to the specimen shall always be equal.

5.1

Mounting of specimen

The specimen shall be mounted by one of the following two methods, depending on the method of preparation
used. The axial stress acting at the upper end of the specimen must be 10 kN/m2 or less, from the time the cap
is placed on upper end of the specimen until the negative pressure or the external pressure and internal pressure
are applied to the specimen. Sufficient care shall be taken not to disturb the specimen when installing thespecimen. In particular, when installing specimens prepared by the trimming method, sufficient care shall betaken not to excessively disturb the top and bottom ends of the specimen with the ribs installed on the cap andthe pedestal.
a)Specimen prepared by the trimming method
1)

Mount the specimen on the pedestal to which the internal rubber sleeve has been fitted, apply theexternal rubber sleeve, and tighten the rubber sleeves to the pedestal and the cap using the O-ring or
similar. Take care that there is no misalignment between the central axes of the specimen and thepedestal.

Note 1: Place filters for drainage onto the upper and lower surfaces and around the side of the specimen as needed.
Note 2: In the case of frozen specimens, the cap and the pedestal shall be cooled in advance as needed.

2)

Assemble the pressure cell and inject water into the cell and the hollow part of the specimen. If
necessary, apply an appropriate magnitude of isotropic pressure to the specimen in the drained state
as needed. The isotropic pressure shall be about 20 kN/m2, and shall be lower than the prescribed
effective stress in the lateral direction at the termination of consolidation. At this state, measure theaxial displacement Hi (mm) and the volumetric change Vi (mm3) with an allowable tolerance of 0.1%of the specimen height and volume, respectively. If the specimen is frozen, thaw it by any of thefollowing methods.

2.1)

Method of thawing under negative pressure
Allow the specimen to thaw while keeping it under appropriate negative pressure. The magnitudeof this negative pressure shall be about 20 kN/m2, and shall be lower than the prescribed effective
stress in the lateral direction at the termination of consolidation. After thawing, measure the height,
external diameter, and internal diameter of the specimen with a precision of 0.1% or better todetermine the resulting axial displacement Hi (mm) and volumetric change Vi (mm3) due tothawing. Assemble the pressure cell, and inject water into the cell and the hollow part of thespecimen. By controlling the external pressure, internal pressure, negative pressure, and axial loadso that the effective isotropic stress in the specimen does not change, replace the negative
pressure with external pressure and internal pressure.

2.2)

Method of thawing under cell pressure
Assemble the pressure cell and inject water into the cell and the hollow part of the specimen. Applyexternal pressure and internal pressure, and allow the specimen to thaw under appropriate

6© JGS 2018 – All rights reserved

JGS 0550-2020

isotropic pressure. The isotropic pressure shall be about 20 kN/m2, and shall be lower than theprescribed effective stress in the lateral direction at the termination of consolidation. Measure theresulting axial displacement Hi (mm) and volumetric change Vi (mm3) with an allowable
tolerance of 0.1% of the specimen height and volume, respectively. If it is not possible to directly
measure the volume change Vi, measure the axial displacement Hi (mm) of the specimen withan allowable tolerance of 0.1% of the specimen height, and calculate the volumetric change in thespecimen Vi (mm3) from the following equation, which assumes that an isotopic strain is producedin the specimen.

Vi =
b)

3H i
Vi
Hi

Specimen prepared by the negative pressure method
Assemble the pressure cell and inject water into the cell and the hollow part of the specimen. By controllingthe external pressure, internal pressure, negative pressure, and axial load so that the effective isotopic
stress in the specimen does not change, replace the negative pressure with the external pressure andinternal pressure.

5.2

Saturation of specimen

Refer to the following for the methods available to saturate the specimen. Volume changes that occur as a resultof the saturation process shall be measured as required.
a)b)When there is a need to increase the degree of saturation of a specimen, an appropriate combination of
the following four methods should be used according to the soil type and the state of the specimen.
1)

Passing deaerated water through the specimen under cell pressure

2)

Applying sufficient back pressure.

3)

Apply methods 1) and 2) after replacing void air inside the specimen with carbon dioxide gas under acell pressure

4)

Extraction of air from within the specimen by applying a negative pressure of about 90 kN/m2 to thespecimen and to the pressure cell and the hollow part of the specimen without changing the effective
isotropic stress. Supply deaerated water while applying the negative pressure as needed.

Back pressure ub (kN/m2) within the specimen and isotropic pressure shall be applied simultaneously tothe specimen, without changing the effective isotropic stress within the specimen. The value of the backpressure shall be about 50 to 200 kN/m2, and in order to avoid fluctuations in the effective stress in thespecimen during pressurization, it is desirable that it be applied gradually as follows. Close the drainage
valve connected to the burette, and apply an appropriate increment of isotropic stress to the specimen.
Then, apply an equivalent magnitude of back pressure and open the valve with. In this way, the differencein the isotopic stress and the back pressure acting on the specimen is always maintained at the initially setpressure difference. Repeat this operation until the back pressure reaches the prescribed value. The
increments of the isotropic pressure and the back pressure for each step shall be set by paying attention
to keep the effective stress to be lower than the prescribed effective stress in the lateral direction at thetermination of consolidation, even when the degree of saturation of the specimen is low, exhibiting a small
B value.

Note:

c)

Appropriate values of the increments of the isotropic pressure and the back pressure are typically 10-50 kN/m2.

Measure the axial displacement Hi (mm) and the volumetric change Vi (mm3) of the specimen from theinitial state until prior to consolidation with an allowable tolerance of 0.1% of the specimen height andvolume, respectively. These include Hi (mm) and Vi (mm3) measured in 5.1a).

© JGS 2018 – All rights reserved

7

JGS 0550-2020
Note: If the volumetric change Vi cannot be directly measured, then Vi may be calculated from the following equation,
which assumes that an isotropic strain is produced in the specimen. If Vi is obtained using this equation, it shall be clearlystated in the reporting items.

Vi =

6

3Hi
Vi
Hi

Reporting

The following items of the specimens shall be reported.
a)Type of soil

Note:

Report the density of soil particles (Mg/m3), the liquid limit (%), plastic limit (%), the minimum dry density (Mg/m3),

and the maximum dry density (Mg/m3) as needed.

b)Specimen preparation methodc)

Initial height (mm), external diameter (mm), internal diameter (mm), and volume (mm3) of the specimen

Note:

Report the wet density (Mg/m3), dry density (Mg/m3), void ratio, degree of saturation (%), and the relative density(%) of the specimens in their initial state as needed.

d)

The initial mass (g) and water content (%) of the specimens if measurede)

The axial displacement (mm) and volumetric change (mm3) of the specimen that occur from the initial state
until prior to consolidation (before testing), and the measurement usedf)

Details of any difference between the methods specified in this standard and the methods actually used. If
the specimen is separated from a large lump sample or if part of a tube sample is used, provide sketchesof the sections taken. If a sample is prepared by compaction or preconsolidation, report the method usedalong with the test results.

Note:

g)

8

If necessary, report the ambient temperature at the time of preparation.

Other reportable matters© JGS 2018 – All rights reserved

JGS 0550-2020

Internal mold fixing equipment
Internal mold (divided in 4)
Internal rubber sleeve
CollarExternal rubber sleeve

Specimen

External mold (divided in 2)

Negative pressure
Metal rib
Porous plate
PedestalPressurechamber bottom
plate

Figure 1 Example of a hollow cylindrical test specimen being produced by the negative pressure
method© JGS 2018 – All rights reserved

9