― 41 ―Research Reports of the National Instituteof Industrial Safety, NIIS-RR-2004（2005）
UDC 624.131.22：539.412

新しく開発した引張り試験装置による粘性土の引張り強度について
スレンダラ B. タムラカル＊，豊澤康男＊＊，伊藤和也＊＊Tensile Strength of Soil Measured Using Newly Developed
Tensile Strength Apparatus
By Surendra B. T AMRAKAR＊, Yasuo TOYOSAWA＊＊ and Kazuya ITOH＊＊
Abstract: Recently, many soil-slopes get failed during the excavation or trimming process of slopes.
In case of circular slope failure, it is generally thought that the failure is occurred due to shearingof soil layers. In such case, shearing surfaces are also seen at the failure sites. But in some failure
excavation sites, such types of shearing surfaces are not seen. Instead soil layers seem to be
detached from each other. The cause of such failure could be due to the development of tensile
cracks. Also, many earth dams, embankments, pavements, etc. are failed due to the developmentof tensile cracks. In addition, location of the development of ice lens in freezing soils is also relatedwith tensile strength. In order to understand the development of tensile crack, it is necessary toknow the exact value of tensile strength that the particular soil consists of. Several methods oftensile testing of soils have been used in the past. But up to now, due to limitations of the existing
test methods, the earlier tests were focused on to the more brittle and elastic materials（stiff,
compacted and cement mixed soils）which have higher tensile strengths rather than for ductile（soft,
saturated and clayey soils）materials which have lower tensile strength.
This paper describes a newly developed tensile strength measuring apparatus which could be used
for measuring the tensile strength of saturated, compacted and soft soils. At first, the tensile
strength measurement procedure using this apparatus is explained which is very simple and quick.
Then, two types of tensile molds are described and results obtained using them are compared.
Statically compacted soils；Kanto loam, clay-sand mixture, clay-silt mixture and CFP silt-sand mixture,and one dimensionally consolidated NSF-clay are used as test samples. Unconfined compression test
and suction test are also performed for Kanto loam to get their relationship with tensile strength.
1）Maximum strengths for Kanto loam are obtained around 50〜60％ of water content for all thesamples prepared at three different dry densities（rd＝0.66，0.68 and 0.7 g/cm3）. In the dry side
（water content lower than 60％）, strengths are reduced with the decrease in water content whereas
in the wet side（water content higher than 60％）
, strengths are decreased with the increase in watercontent. Difference in the strengths due to change in dry density at dry side is lower than that at
wet side.
2）For compacted Kanto loam, it is found that the average ratio of unconfined compression
strength（qu）to tensile strength（qt）is around 12.5. But it varies differently with water content at
dry and wet sides.
3）The effect of the amount of finer particles and their size on tensile strength are also observed** 科学技術振興事業団 重点研究支援協力員 Supporting Staff for Priority Research Japan Science and Technology
Corporation** 建設安全研究グループ Construction Safety Research Group

産業安全研究所研究報告― 42 ―

NIIS-RR-2004（2005）

by changing the proportions in the mixtures in clay-silt, clay-sand and sand-silt. It could beobserved that with the increase in the amount of finer particles, tensile strength increases. But
with the increase in the size of finer particles, there is a reduction in tensile strength.
4）In case of pre-consolidated saturated NSF clay, tensile and unconfined compression tests are
performed. Saturated NSF clay samples are prepared under the pre-consolidation stresses of 100,
200 and 300kPa. The ratio of strength（qu/qt）obtained for this saturated NSF clay is around 6.
Keywords; strength, tensile crack, test equipment, compacted soil, Kanto loam, NSF clay

1. Introduction

saturated soil specimen prepared in the special
consolidation mold to the tensile mold of thisIn order to understand the development oftensile cracks which leads to the failure of slopes,

apparatus, one can easily measure the tensile
strength of saturated soft soils. Test results oncompacted and saturated soils shows that they are
reproducible, and reliable. Effect of water content,
dry density and the proportions and size of fineearth dams, embankments, pavements and ice lensdevelopment process during the freezing of soils,
it is necessary to know the exact value of tensile
strength that the particular soil exhibits. The
development of a simple and appropriate method

particles mixed in the soil are examined.

2. Testing Apparatus

for the determination of tensile strength in thelaboratory is necessary. In the past, tensile
strength of soils has been generally neglected.
Because the tensile strength of the soils, especially
soft and saturated ones, is considered to be zeroor relatively very small in comparison tocompressive strength. Furthermore it is difficult
to measure the tensile strength directly in thelaboratory. Several methods of tensile testing ofsoils, such as uniaxial direct tensile test , a simple
splitting test and unconfined penetration test,

Tensile test apparatus（ Fig.1, Photo. 1 andPhoto. 2 ）consists of a two halves box；a fixedbox and movable one, resting on a horizontal
platform. Inside this box, a newly developed tensile
mold is placed. This tensile mold consists of two
separate C structures whose inner shape is

flexure（beam）test, indirect Brazilian test, hollow
cylinder tests, etc., have been used in the
past1）〜8）. But up to now, due to the limitations in
those test methods, the earlier tests were only
focused on to the more brittle and elastic materials（stiff, compacted and cement mixed soils）having
higher tensile strength rather than for ductile
materials（soft, saturated and clayey soils）having
lower tensile strength. Few researches have been
made to measure the tensile strength of soils
having lower tensile values 9）〜 11）. But those aremostly applicable to unsaturated soils rather thansaturated soft soils.
In this paper, a new simple testing apparatus
which can be easily used for both compacted andsaturated soft to medium soils is described and thetesting method is explained. Compacted soil
specimen can be directly prepared within the moldof the apparatus itself. Also, by transferring the

Fig. 1

Outline of tensile apparatus with type-A mold.

新しく開発した引張り試験装置による粘性土の引張り強度について― 43 ―

almost circular except at the portion where these
two halves join. This mold holds the specimen
and its two halves are screwed to the apparatus
box. One box of the apparatus is fixed to thehorizontal platform while the other box can move

perpendicular to horizontal pulling.
To see the effect of stress concentration at themost constricted part of the specimen during thepulling, two types of tensile molds having different
structures are used. These molds can be easily

freely on the horizontal platform.
To reduce the friction between the movable box

changed as they are connected to the main
apparatus by the screws only. In the first type

and platform, linear sliding rollers are placed below
the movable box and above the platform. The
movable box is pulled away in a horizontal direction（type-A, Photo. 1 , Fig. 1 ）, there is no bridging
structure between the two halves whereas in thesecond type（ type-B, Photo. 2 ） , bridging

until the soil specimen fails in tension as indicatedby tensile crack appearing at the middle of thespecimen where the two halves of the mold are
attached. The load cell placed between the
movable box and motor axis measures the tensile

structures are placed in between the two halves（1 cm in thickness）. The total surface area oftype-A mold is 38.51cm2（total volume＝192.53 cm3）

load.

types of mold is 3 cm and depth is 5 cm.
The apparatus box along with the mold andplatform can be completely separated from the

The tensile strength is obtained by dividing

the tensile load by the area of the tensile crack

and that of type-B mold is 41.51 cm 2 （ total
volume＝207.53 cm3）
. The minimum width for bothmotor for preparing the specimen before the test.
Compacted soil specimen is prepared within thismold by direct static compression whereas
saturated specimen is prepared by direct transfer
of consolidated specimen prepared in aconsolidation mold. Once the specimen is readywithin the mold for the test, then it is connected
to motor shaft. A load cell is attached between
the motor shaft and the movable apparatus box.
The rate of deformation is maintained at
0.35 mm/min.
Unconfined compression tests are performed ina standard unconfined compression test unit andPhoto. 1

Tensile apparatus with tensile mold（typeA）.

constant strain rate is maintained. The height ofthe specimen is 10 cm and diameter is 5 cm.
Specimen is allowed to fail at a constantdisplacement rate of 0.1 mm/min. Suction test is
performed using a simple suction testing
apparatus12）.

3. Materials, Specimen Preparation andInstallation
3.1 Materials
Index properties of materials used in thisresearch are shown in Table1. Soil particles
passing through the 2mm sieve are used for Kanto
Photo. 2

Tensile apparatus with tensile mold（typeB）.

loam.
To examine the effect of the amount and the― 44 ―

産業安全研究所研究報告

NIIS-RR-2004（2005）

is applied all over its inner surfaces.
Compacted specimens are prepared by thoroughly
mixing the materials with prerequisite distilledwater and then kept in a plastic bag and sealed
for a week so that water is uniformly distributed
within the material. Then, the specimens areprepared by directly and statically compressing theprerequisite amount of water mixed material within
the tensile mold of this new apparatus, using
bellofram cylinder water content maintained for
Kanto loam is varied from 30 to 100％.

Compacted

Kanto loam specimens are prepared at three dry
densities（r d ）；0.66, 0.68 and 0.70 g/cm 3 . In thecase of clay-silt mixtures, they are mixed in thefollowing proportions by weight；25：75, 40：60,
50：50, 60：40, 75：25 and for clay-sand they are
mixed in following proportions；30：70, 35：65,
40：60, 45：55, 50：50, 55：45, 60：40, 65：35 and70：30. Similarly, for silt-sand mixtures, they are
mixed in the following proportions；00：100, 20：
80, 40：60, 50：50, 60：40, 70：30, 80：20 and

Fig. 2Grain size distribution curves for diffferent
materials.

size of soil particles, three types of mixtures wereprepared；（a）clay-silt,（b）clay-sand and（c）siltsand. Here, clay means NSF clay and silt means
CFP-100 silt13）. This CFP-100 silt is prepared by

100：00. Water content,（w）for all the mixtures
is maintained around 10％. Dry densities for claysilt, clay-sand and silt-sand mixtures, aremaintained at 1.5, 1.5 and 1.4 g/cm3, respectively.
Pre-consolidated saturated NSF clay specimen is
prepared by thoroughly mixing NSF clay powder
with distilled water using a mixer until it changes
to slurry. The amount of water mixed is two times

crushing silica sand. Sand used is standard
Toyoura sand. NSF clay, silt（ CFP-100） andToyoura sand are commercially available. Grain size
distribution curve for each material is also shownin Fig. 2. For saturated sample, NSF clay is used.
3.2 Specimen Preparation and Testing Procedure
Type-A and type-B molds are first assembled asshown in Photo. 1 and Photo. 2. Type-A is
simpler and easier to handle. To prevent the freemovement of the movable part of the apparatus
box before testing, the movable box is screwed tothe horizontal plate of the apparatus. Also, toreduce the friction between the specimen and theinner wall of the tensile mold, a thin film of grease

Photo. 3

Consolidation mold for saturated soil.

新しく開発した引張り試験装置による粘性土の引張り強度について― 45 ―

the liquid limit of NSF clay. After the slurry waspoured into the consolidation mold（Photo. 3 ）,two days de-airing was done by keeping theconsolidation mold within a big cell under vacuum.
The cross-section of the consolidation mold is

3.3 Testing Proceduresimilar to that of the type-A tensile mold. At thebottom of this mold, there is a detachable plate

the load cell is set up towards the pulling side of
the mold box. Finally, the screws which were
earlier fixed to prevent the movement of movable
box of the apparatus are un-screwed. In the casewith porous stone whereas on the top, there is apiston shaft which has many small holes on it.
Drainage is allowed via these two parts during

After the completion of compaction in the caseof compacted specimens or after the insertion of
the consolidated specimen into the tensile mold,of type-B mold, extra bridging structures have toconsolidation. One dimensional consolidation isdone by putting the loads on the loading plate（seePhoto. 3 ）. Consolidation stresses applied to theslurry are 100, 200 and 300kPa.
Once the consolidation is over, the bottom porous

be removed carefully.

plate and filter paper are detached from the

But the difference in the values of tensile strength
obtained is very small, displacement rate
0.35 mm/min showing the minimum value. Hence,
all the tests are carried out with the displacement
rate of 0.35 mm/min.

consolidation mold. Then the mold with theconsolidated specimen is placed over the tensile
mold. Centering of mold is done by guiding
support screws which are attached to the fixed
portion of the tensile mold. By pushing the shaft

For this, lots of attention

has to be paid. Hence, from the simplicity of thetesting procedure, type-A mold is better than typeB mold. Test results with tensile pulling rate of
0.17, 0.35 and 0.86 mm/min are done and compared.

4. Results and Discussionsof the consolidation mold slowly, the consolidated
specimen is allowed to be inserted into the tensile
mold. Once the full depth（ 5 cm） insertion iscompleted, then it is separated from the tensile
mold by using a wire saw which is also used for

Test results of tensile tests carried out on typeA and type-B molds for clay-sand mixture（rd＝1.44 g/cm3 and w＝10％）are shown in Fig. 3.
Both types of molds gave almost the same peak

final trimming of the upper surface of the specimen
after the insertion into the tensile mold.
In the case of tensile test specimen, materials
are kept within the tensile test mold whereas
specimens for unconfined compression and suction

strength and showed the similar stressdisplacement behavior. As the testing procedure
with type-B is complex in comparison to type-A,

tests, materials are kept within the splitting mold.
Water content and dry density of the specimens
are the same for all the tests. Dimension of tensile
test specimen is the same as that of tensile moldwhereas the height and diameter of the unconfinedcompression test specimen are 10cm and 5 cm,
respectively. Similarly, the thickness and thediameter of the suction test specimen are 2 cm and5 cm, respectively. Unconfined compression test isdone at a constant displacement rate of 0.1 mm/min.
Suction tests are only done for Kanto loam soil
with dry density of 0.70 g/cm3.

The air entry value（AEV）of the ceramic disk used in the suction test
is 240 kPa.
Fig. 3Results from type-A and type-B molds（clay-sand mixtures：r d＝1.44g/cm3, w＝10％）

― 46 ―

産業安全研究所研究報告

NIIS-RR-2004（2005）

it is therefore suggested to use type-A mold. From
now on, test results obtained using the type-A moldare only explained.
Tensile cracks developed during the compacted
and saturated tensile tests for different specimens

0.1 mm displacement. Here, the maximum tensile
strength is the maximum tensile stress necessary
to break the most of the soil particle bonds. Thus,
tensile stress keeps on reducing even after reaching
the maximum value. Some researchers have also

are shown in Photo. 4. The clear separation of
specimen into two parts could be seen in all thementioned about the similar trend of decrease intensile stress after the maximum value11），14）. On
the top surface of the specimen, tensile crackdevelopment could be seen during the test. In
case of compacted specimens, cracks are developed

tests. Tensile crack surfaces are also smoothshowing the clear detachment from each other as
those are generally seen at slope failure sites where
slopes are failed due to tensile cracks.
Macroscopically, detaching surfaces（failure planes）
are smooth and it shows that there is an even
distribution of tensile force along the failuresurfaces. But if the tensile failure surfaces arethroughout the surface almost at the same time.

studied microscopically, there is little variation ondifferent water content with repetition. Although,there are some differences in the maximum tensile
strength for the repeated water content, it can besaid that reproducible results can be obtained withthis new apparatus. Relationship between qt, rd

the surface which is due to the difference in the
distribution of soil particle size.
The plots of tensile stress versus displacement
for compacted Kanto loam are shown in Fig. 4.
Good and clear stress-displacement curves can beseen with the maximum tensile stress, qt（tensile
strength）developing within the range of 0.05 to

While in the saturated specimens, crack is at firstseen at the outer side and it continuously protrude
inward till whole the surface is separated.
Fig. 5 shows the results of Kanto loam tests at

and w for Kanto loam are shown in Fig. 6.

Threedistinct curves are seen for three different dry
densities. But all the curves show similar trends
giving maximum tensile strength around 60％ ofwater content. Tensile strength decreases along
both sides of this maximum value.
Comparing the three curves, it can be said thatwith the increase in dry density, tensile strength

Photo. 4

Tensile cracks produced during the tests；
秬compacted Kanto loam
（w＝40％，r d＝0.7g/cm3），
秡saturated clay（200kPa）.

Fig. 4Stress-displacement curves（ for compacted
Kanto loam, r d＝0.66g/cm3）.

新しく開発した引張り試験装置による粘性土の引張り強度について― 47 ―

also increases. But the difference in the tensile
strength values with the change in dry density at
two sides of maximum tensile strength is different,
showing larger difference at the dry sides（lower
than 60％ water content）and smaller difference atupon the amount of water content.
Unconfined compression test results performed
for compacted Kanto loam are shown in Fig. 7.
Here, the maximum qu is seen around 50％ of watercontent. The trend of curves is almost similar towet sides（higher than 60％ water content）. At
nearly saturated condition, tensile strength values

that for tensile tests results shown in Fig. 6.
Relationship between qu and qt is shown in Fig.

are almost same. Therefore, it could be said thatwith the increase in dry density tensile strength
also increases, but the ratio of increment depends

8. In plotting the direct relationship between
these strengths, their ratio varies from 10.64, 13.1
and 12.69 depending upon the dry densities equal
to 0.66, 0.68 and 0.70 g/cm3, respectively. Taking
the average, it can be said that qu is 12.5 times
larger than qt in case of Kanto loam. Krishnayya
et al. have also showed this ratio in the range of
12 to 32 for Mica Till6）.
In Fig. 9, it can be observed that the slope of
this ratio is different at dry and wet sides. With
the increase in water content, this ratio increases
at dry sides and decreases at wet sides. But thedecreasing ratio of qu/qt at wet side is much less,showing the average value of 10.

Hence, it isnecessary to consider the water content if the qt

Fig. 5

Reproducibility of tests（for Kanto loam）.

Fig. 6

Relationship between qt, w and r d（for compacted Kanto loam）.

value is to be estimated from the calculated qu.
To see the effect of initial suction on tensile
strength of compacted Kanto loam, simple suction

Fig. 7

Relationship between qu, w and r d（for compacted Kanto loam）.

― 48 ―

産業安全研究所研究報告

tests are conducted and their results are shown in
Fig.10. It is to be noted that the suctions
measured here are the suctions at the beginningof tensile testing. So, it is not necessarily thesuctions when tensile failure occurred. Suction tests

NIIS-RR-2004（2005）

are carried out by applying the back air pressure12）.
Fig.10 shows the difference in the values ofsuction and qt at the same initial water content.
This indicates that the qt value measured does not
fully represent the initial suction of the specimen.
Only some effect of suction is included in the qt.
Relationship between the tensile strength andsuction is also shown by Tang et al.2）. Their results
also showed that the measured suction is not equal
to tensile strength. Instead, tensile strength values
are much lower than the suction measured.
The effects of amount and size of finer particles
in the tensile strength are shown in Fig.11 andFig.12. Here, finer particles mean the clay in theclay-silt and clay-sand mixtures and silt in the siltsand mixture. tensile test results of the mixtures；clay-silt, clay-sand and silt-sand are shown. All
the curves show similar trend of increment in qt
and qu with the increase in the amount of finerparticles；i.e. the ratio of clay in the clay-silt andclay-sand mixtures and silt in silt-sand mixture.
This implies that with the increase in the finerparticles, both qt and qu increase.
Comparing the strength of mixtures compacted
at r d＝1.5 g/cm3 for clay-silt and clay-sand mixtures,
it is seen that the strengths（qt and qu）of clay-

Fig. 8Relationship between qu and qt（for compacted Kanto loam）.

silt mixture is higher than the strength of clay-

Fig. 9Relationship between qu/qt and w ％（for compacted Kanto loam）.

Fig. 10

Relationship between suction, w ％ and qt for
Kanto loam（r d＝0.7g/cm3）.

新しく開発した引張り試験装置による粘性土の引張り強度について― 49 ―

sand mixture. Here, clay-silt mixture shows thehighest strength and silt-sand mixture shows thelowest strength. Since the size of clay particles
is smaller than the size of silt and sand particles,
it can be said that the size of fine particles affects

According to Barzegar et al., different amount offiner particle shows different modes of particle
arrangements within the soil matrix which influence
the soil fabric and hence, the strength 15）. The
effect of cohesion is not studied in this paper. But

tensile strength；the larger the size of the fineparticles, the smaller the tensile strength becomes.

it might be thought that the effect of cohesion will
be more prominent in saturated clayey soils rather
than unsaturated compacted soils.
Relationship between the strengths and pre-This might have occurred as there is a direct
relationship between contact points of soil particles
and strength of soils. Soils having more fineparticles increase the contact surfaces between theparticles which then increases the strength.

Fig. 11

Fig. 12

consolidation stress of saturated clays is shown in
Fig.13 and Fig.14.
With the increase inconsolidation stress, both q t and q u strengths
increase, showing their strength ratio（qu/qt）equal
to 6. Friction between the slurry specimen andinner surface of the consolidation mold might haveTensile strength of compacted mixtures.

Unconfinedcompressive
compacted mixtures.

strength

Fig. 13Pre-consolidation stress and qt.

Fig. 14Pre-consolidation stress and qu.

of産業安全研究所研究報告― 50 ―

NIIS-RR-2004（2005）

affected the propagation of stress uniformly
throughout the depth of the consolidation
specimen. Also, some disturbances that might
have occurred during the insertion of theconsolidated specimen from the consolidation moldPre-consolidated Saturated clay
8. Relationship between the tensile strength andthe consolidation stress for the saturated clay showthat with the increase in the consolidation pressure,there is increase in tensile strength. The ratio

to the tensile mold of the apparatus. So, proper
attention must be paid during the specimen（qu/qt）obtained for pre-consolidated saturated clay
specimen is around 6.

preparation.

Acknowledgement

6. Conclusions

Theauthors

would

like

to

acknowledge

From the tests conducted for staticallycompacted Kanto loam, clay-silt mixtures, clay-sandmixtures and silt-sand mixtures；and saturated
clay, the following points can be concluded；
1. Newly developed tensile test apparatus can be

Professors T. Mitachi and S. Akagawa of Hokkaido

used for measuring tensile strength of bothcompacted and pre-consolidated clayey soils. Bothtype-A and type-B tensile molds give similar

unconfinedcompression
tests
data
of
preconsolidated NSF clay and suction data of Kantoloam. The authors would like to express their
gratitude to Senior Researchers；Mr. N. Horii and
Mr. S. Tamate and Researcher, Mr. T. Ariki for
their valuable suggestions and discussions during

results. Sample preparation in the type-A mold iseasy and simple.
2. Reproducibility of the test results is also
verified.
Compacted Kanto loam
3. Maximum tensile strength and compressive
strength are obtained around 50 to 60％ of watercontent. With the increase in dry density, tensile
strength and compressive strength also increase.
The difference in the increment due to dry density
is higher at the dry side than that at the wet side.
At higher degree of saturation, differences become
smaller.
4. The ratio of qu and qt is around 12.5, for Kanto

University for their continuous inspiration incarrying out this research. In addition, the authors
would like to extend their heartfelt thanks to Mr.
Y. Kudoh of Hokkaido University for providing

the experiments.
References
1）Tschebatorioff, F.P., Ward, E.R. and De Phillipe,
A.A.:The tensile strength of disturbed andrecompacted soils, Proc. 3rd Int. Conf. on SMFE,
1, 207〜210（1953）.
2）Tang, G.X. and Graham, J.A.:Method for testingtensilestrengthinunsaturated
soils,
Geotechnical Testing Journal, GTJODJ, 23-3, 377〜382（2000）.

loam. But there is a variation in this ratio withthe water content. At the dry side, it increases

3）Sasaki, Y., Inagawa, N., Saito, K., Tobita, Y. andYamaguchi, A.:Development of Tensile strengthwith the increase in water content, while at thewet side, it remains almost constant.

apparatus and problems during test, Conferenceof Japanese Society of Civil Engineers, JSCE,

5. Difference between the suction and tensile

Northeast branch, 386〜387（2003）（in Japanese）.

strength values becomes larger with the decreasein water content.
Compacted mixtures of clay-silt, clay-sand and siltsand
6. From test results of mixtures, it can be said4）Fang, H.Y. and Fernandez, J.:Determination oftensile strength of soils by unconfinedpenetration test, Laboratory shear strength ofsoil, ASTM STP 740, 130〜144（1981）.
5）Ajaz, A and Parry, R.H.G.:Stress-strain behavior

that with the increase in the amount of finerofparticles（clay or silt）, qt and qu both increase.

compression, Geotechnique, 25-3, 495〜 512（1975）.

7. Also, with the decrease in the size of the finerparticles（size of clay is smaller than size of silt
and sand）, there is increase in the strength.

twocompacted

clays

in

tensionand6）Krishnayya,
A.V.G.,
Eisenstein,Z.
andMorgenstern, N.R.:Behavior of compacted soil in新しく開発した引張り試験装置による粘性土の引張り強度について― 51 ―

tension, Geotechnical Engineering Division,
ASCE, 100-GT9, 1051〜1060（1974）.
7）Narain, J. and Rawat, P.C.:Tensile strength ofcompacted soils, Journal of Soil Mechanics andFoundations, ASCE, 96-6, 2185〜2190（1970）.

12）Mitachi, T., Kudoh, Y. and Tushima,
M.:Evaluation of in-situ undrained strength ofsoft soil deposits by use of unconfinedcompression test with suction measurement,
Soils and Foundations, 41-5, 61〜71（2001）.

8）Mosaid, A.:Tensile properties of compacted soils,
Laboratory shear strength of soil, ASTM STP

13）Kawamura, Y., Itoh, K., Suenuma, N. and740, 207〜225（1981）.
9）Suzuki, T., Umei, T. and Sunaga, F.:A researchon the tensile strength of cement treated soils,
53rd Annual meeting of Japanese Society of Civil

Katada, T.:Model tests on bearing capacity ofcircular footings on dry silt, Proc. of the 39th
Japan National Conference on GeotechnicalEngineering, 696/E-03, 1389〜1390（2004）.

Engineers, JSCE, 600〜601（1998）（in Japanese）.
10）Yao, S., Masui, T. and Ito, A.:The relationshipbetween tensile strength and the state of waterin Kaolin clay, 47th symposium on Geotechnical14）Ohkubo, S., Fukui, K. and Kimura, A.:Dynamic
quality and constitution equation for Dotansoil, Tunnel and Underground, 33-1, 45〜50（2002）（in Japanese）.
15）Barzegar, A.R., Oades, J.M., Rengasamy, P. andsymposium, 127〜132（2002）（in Japanese）.
11）Ono, N., Mochizuki, A., Kurosaki, H. and Ueno,
K.:Trial tests with compressive and tensile

Murray, R.S.:Tensile strength of dry, remouldedsoils as affected by properties of the clay
fraction, Geoderma, 16, 93〜108（1995）.

strength measuring apparatus, 58 th Annual
meeting of Japanese Society of Civil Engineers,
JSCE, 337〜338（2003）（in Japanese）.

（平成16年12月28日受理）