Evaluating the Saturated Permeability Coefficients ofRiver Embankments via Field Permeability Tests
Keita Lee1, Takeshi Kodaka2*, Masanori Ishihara3 and Yuichi Kubo4
1Nippon Koei, Osaka, Osaka, Japan
2Meijo University, Nagoya, Aichi, Japan
3Public Work Research Institute, Tsukuba, Ibaraki, Japan
4Geolabo Chubu, Nagoya, Aichi, Japan*kodaka@meijo-u.ac.jp

Abstract. The authors conducted field permeability tests on numerous river embankments using a Marriott siphon in 30-cm test holes to obtain their saturated
permeability coefficients. The results revealed that the field-obtained saturated
permeability coefficients were larger than those obtained as a result of the laboratory permeability test conducted on the undisturbed specimens sampled fromthe same location. Regarding embankments constituted by fine-grained soils,
there are cases in which the field-obtained coefficients are several orders of magnitude larger than those obtained under laboratory conditions. These results suggest that the field permeability coefficient obtained by the Marriott siphon withlarge-diameter test holes evaluates the macroscopic permeability, including insitu heterogeneity and anisotropy. In this study, the results of the field permeability tests at two embankments of the Oda and Kano Rivers are shown. In addition, the results of the laboratory permeability test for the undisturbed specimens
sampled at each field site are shown. In each survey, the field permeability coefficients were larger than both the laboratory permeability coefficients and theestimated value from particle size, as in the case of other embankments investigated so far.
Keywords: river embankment, permeability, field permeability test, laboratory
permeability test

1

Introduction

In the qualitative inspection of river embankments, it is crucial to evaluate the permeability coefficient of embankments. The authors conducted field permeability tests on
old river embankments [1]–[3] or banks damaged by floods [4] using a Marriott siphon
with 30-cm test holes to obtain their saturated permeability coefficients. Previous studies confirmed that the saturated permeability coefficients obtained at the field are generally larger than those obtained as a result of laboratory permeability tests conducted
on undisturbed specimens sampled at the same location. Regarding embankments constituted by fine-grained soils, there are cases in which the field-obtained coefficientsare several orders of magnitude larger compared to those obtained under laboratory2conditions. These results suggest that the field permeability coefficient obtained by the
Marriott siphon with large-diameter test holes evaluates macroscopic permeability, including in situ heterogeneity and anisotropy.
In this study, the results of the field permeability tests conducted at two embankmentsof the Oda and Kano Rivers are presented. An open-cut investigation was conductedon the collapsed banks of the Oda River, which was damaged by heavy rain in July
2018. At that time, a field permeability test was conducted using a Marriott siphon at
multiple points on the embankment. Furthermore, a field survey was conducted in December 2020 on the embankment excavation section of Kano River. In addition, theresults of the laboratory permeability test conducted using undisturbed specimens sampled at each field site are presented. In each survey, the field permeability coefficientswere larger than both the laboratory-obtained permeability coefficients and values estimated from particle size; a similar trend has been observed in the other embankments
investigated so far. In this study, we demonstrate how to conduct such a field permeability test easily using a water meter and show its usefulness.

2

Field investigation at Oda River embankments

2.1

Field permeability test

The field permeability test was conducted at two breach locations (3.4km point, hereafter just 3.4k, on the left bank and 6.4k on the left bank) and two slip failure locations(0.6k on the right bank and 4.2k on the left bank) of the Oda River. At each site, opencut investigations at the embankments were conducted to determine the causes of Dyke
failures. Fig. 1 shows the cross-sectional view of the open-cut investigation conductedat the 3.4k on the left bank and locations where the field permeability test was conducted. The photograph framed in red shows the operational conditions of the field
permeability test. The numbers ① to ③ in white located at the execution positions
correspond to the results reported in Table 1. Figs. 2 and 3 show the locations of the
field permeability tests conducted during open-cut investigations at 6.4k on the leftbank and 0.6k on the right bank. The white numbers in Fig. 1 correspond to the resultsin Table 1. The left bank result obtained at 4.2k is omitted owing to space limitations.
Table 1 summarizes the results of the field permeability tests starting from the downstream side. As mentioned above, the numbers ① to ⑥ in the table indicate the locations where field permeability tests were conducted on the cross-sections investigatedin Figs. 1 to 3, respectively. The saturated coefficient of permeability obtained from thefield permeability test is presented in the middle column of the table. The soil properties
near each test hole are also shown; however, note that they do not necessarily denotethe same point. In addition, the coefficient of permeability estimated by Crager's
method with a 20 % grain size, namely 𝐷20, of these soil samples is presented as well.
0.6 km point on the right bank corresponds to an embankment composed mainly ofcohesive soil; however, thin sand and gravel layers exist in places [5]. Consequently,
the field coefficient of permeability is high, which is very different from that of cohe-3

sive soil. In the test conducted at 0.6k ① on the right bank, the steady state was maintained for a while. Subsequently, the coefficient of permeability, shown in Table 1, wasobtained. However, the surrounding cohesive soil collapsed owing to water seepage
into the narrow gravel layer; therefore, the field test could not be continued. At otherlocations, although no noticeable inhomogeneity was observed near the permeability
test points, the values obtained in the field permeability tests were generally larger thanthose estimated from the grain size, approximately three orders of magnitude higher.
This tendency is remarkable in an embankment containing a large number of finegrains. Conversely, the evaluation of coarse-grained embankment soil, such as gravelsand, was consistent with the field permeability test results. However, in the case of the
6.4k upstream cross-section, the difference between the value estimated from the grain
size and field test result appears to be large when there is a large amount of fine grains,even if gravel is sufficiently mixed.

Fig. 1. Process locations and conditions of filed permeability tests during open-cut investigations conducted at the breach location on the left bank at 3.4k.

Fig. 2. Location of field permeability test during open-cut investigations at 6.4k breach locationon the left bank. (Left Fig: Downstream location and Right Fig: Upstream location）

Fig. 3. Location of field permeability test during open-cut investigations at 0.6k slip failure locations on the right bank. (Left Fig: Upstream location and Right Fig: Downstream location）

4
Table 1. Field permeability test results, soil classification, and estimated coefficients of permeability at each location.
Investigationsofembankments

Open-cut(stream)
Downstream

Right bank
0.6k

Left bank
3.4k

Left bank4.2k

Left bank
6.4k

2.2

Upstream

Downstream
Downstream
Upstream
Downstream
Upstream

Test point

Permeability of test point

DetailPhoto

Permeability(m/s)

Classification

Upper step
Downer step
Upper step
(Outfield)
Upper step
(Infield)
Downer step
(Outfield)
Downer step
(Infield)
OutfieldInfield (Inside)
Infield(Outside)
Upper step
Downer step
Infield (Inside)
Infield(Outside)
Upper step
Downer step
OutfieldCenterInfield①②

1.6×10-4
3.1×10-5

(CLS)
(FS)

D20
(mm)
－
0.0016③

4.6×10-5

(CLS)

－

－

④

2.3×10

-5

(CLS)

－

－

⑤

1.9×10

-5

(CLS)

－

－

⑥

6.4×10-5(SC)

0.0046

3.0×10-8①②

3.2×10-6
3.7×10-4(FS)(SP-G)

0.00130.4130－
4.8×10-4③

1.1×10-4(SP-G)

0.32572.7×10-4

－
－
－

-4

2.5×10
3.1×10-5
9.2×10-5(SG-F)(SF)(SF)

0.37000.04000.0780

2.5×10-4
1.8×10-6
8.5×10-6－

4.6×10-5(S-FG)

0.20008.9×10-5

①
②
③
④
⑤

-5

(SC)
(SC)
(SF-G)(SF-G)(SFG)－－
0.01060.00740.0098－－1.1×10-7
6.6×10-8
1.0×10-7

6.2×10
6.9×10-6
6.2×10-5
5.4×10-4
1.4×10-4

Crager's
(m/s)

－
－

Laboratory permeability test

For the laboratory permeability test, samples taken from the open-cut section downstream at 3.4k on the left bank (see Fig. 1) and samples taken from the open-cut section
upstream at 4.2k on the left bank were used. These samples were collected using asimple sampling method [6] near the test hole where the field permeability tests wereconducted. Specifically, a 10-cm simple sampler, which is a 19-cm-high polyvinyl
chloride (PVC) pipe with a cutting edge on one side, was carefully pushed into theground. Subsequently, the soil around the sampler was excavated and removed for sampling. Fig. 4 illustrates the excavation process. The collected samples were temporarilyfrozen and maintained in PVC pipes. Then, they were cut and shaved into specimens
for laboratory permeability tests. Accordingly, to investigate the anisotropy of permeability at a specimen level, two specimens were formed from one PVC pipe in the vertical and horizontal directions, as shown in Fig. 5. Fig. 6 illustrates this procedure. First,
the PVC pipe around the specimen was cut, and the frozen sample was carefully removed. Frozen samples were cut 12 cm from the tip and divided into two groups. Usinga specially processed specimen forming lathe, each specimen was rotated and shaved
with a sharp bit to form a cylindrical specimen with a diameter of 5 cm and height of 9cm.

5

Downward at field(pushed direction)
Vertical direction

Horizontal direction

Fig. 4. Excavated situation

Cut PVC pipe

Form by lathe

Situation

Shaved specimens

Fig. 6. Specimen forming procedure

Fig. 5. Form image

Take out

Fill by Bentonite

Situation after filling

Vacuum degassing

Fig. 7. Laboratory permeability test procedure

Since several samples were collected from the same location, when vertical and horizontal specimens were formed as described above, a laboratory permeability test using
a single PVC pipe frozen sample was also conducted for comparison. At that time, only
the end surface was formed, without cutting the peripheral surface. In addition, since
there is a risk of damaging the sample collected at locations with a large amount ofgravel during specimen formation, the frozen sample was not cut or shaved to be used
as a single specimen for the permeability test. A laboratory permeability test was conducted by placing the frozen specimen in a mold with a diameter of 15 cm. Since there
was a large gap between the mold and specimen, the circumference of the specimen
was filled with bentonite, a material with low permeability. Fig. 7 shows an example ofthe test procedure using a single PVC pipe specimen. The procedure is the same forlateral and vertical specimens with a diameter of 5 cm; only the amount of bentonite tobe filled increases. Fig. 1 shows the state of the field permeability test, as well as thestate of specimen formation during the laboratory tests, which were collected near thetest holes. In Figs. 1 and 5, the cutting edge of each sampler is illustrated upward; however, the samples are collected upside down.
Table 2 summarizes the laboratory permeability test results. At 3.4k on the left bank, a
total of 13 specimens were tested with samples collected at three points. Moreover, at
4.2k on the left bank, a total of seven specimens were tested at four points. The table6

also reports the wet density immediately after formation in the frozen state for eachspecimen. Variations in wet density were observed, even for specimens collected fromthe same sampling point.
Table 2 lists the coefficients of permeability obtained from the field permeability tests
mentioned earlier. Comparing the coefficients of permeability obtained from both tests,
observe that the coefficients of permeability obtained from the laboratory test are generally smaller than those obtained from the field test. A similar trend has been observedin previous studies [1]. In positions where fine grains are considered abundant, there isa difference of one to two orders of magnitude, or even more, in some cases.
Compared with the coefficient of permeability estimated from the grain size, the estimated value appears to be close to the coefficient of permeability obtained by the fieldtest conducted at positions with rich gravel content and high permeability. Meanwhile,the estimated value appears to be close to the coefficient of permeability obtained fromthe laboratory test conducted at positions with rich fine grains content and low permeability.
Regarding the evaluation of anisotropy, the horizontal coefficient of permeability wasapproximately 10 times larger than the vertical one conducted at 3.4k downstream ofthe left bank (outside) ③. However, in this case, a clear difference cannot be observed,
partly because the wet density of the specimen in the vertical direction is slightly higher.
However, the field permeability test itself can be interpreted as an evaluation that includes horizontal permeability anisotropy, which appears to be largely different fromthe laboratory test. Therefore, it is necessary to separately verify the permeable scaleeffect inside the levee body.
Table 2. Laboratory permeability test results, soil classification, estimated coefficient, field
permeability coefficient.
Investigations
Open-cutof(stream)embankments

DetailTest method Direction
Falling head

Outfield①

Left bank
3.4k

Left bank4.2k

Downstream

Downstream
Upstream

Infield(Inside)②

Constant head
Constant head
Falling head
Falling headUpper step

Falling head

Falling head

Downer step Falling head

Falling head
Constant head

Verticaldirection

-8

-9

-9

1.6×10 (1.93) 7.5×10 (2.01)

D 20
(mm)

Crager's
(m/s)

(FS)

0.001

Impossible
to estimate(SP-G)

0.413

4.8×10(SP-G)

0.326

2.7×10(SG-F)

0.370

2.5×10Field
permeability
(m/s)

-6

3.2×108.8×10 (2.00) 6.9×10 (2.00)-5

4.2×10 (1.99)-5
7.0×10 (1.95)-5
5.8×10 (1.95)-7
2.3×10 (1.90)

VerticalVerticalClassification

8.4×10 (1.93)-8

VerticalVerticalVertical &horizontal
Vertical &horizontal
Vertical &horizontal
Vertical &horizontal
Vertical &horizontal

Horizontal
direction-9

VerticalVertical &Falling head horizontal
Vertical &Falling head horizontal
Constant head Vertical

Infield(Outside)③

Infield(Inside)Infield(Outside）

Test hole

Laboratory permeability(m/s)

Test point-4

3.7×10-4

1.1×10-4

2.5×10-6

3.1×10-6

9.2×10-5

4.6×10

-7

-6

-7

-6

-7

-6

-6

-7

(SF)

0.004

1.8×10

-7

(SF)

0.078

8.5×10

5.7×10 (1.78) 9.7×10 (1.67)-4-4

8.6×10 (1.76) 8.9×10 (1.71)
7.7×10 (1.65) 2.2×10 (1.57)
8.4×10 (1.53) 5.5×10 (1.60)-7

2.2×10 (1.57) 3.2×10 (1.69)-6

3.4×10 (1.43)(wet density g/cm3)(S-FG)

0.200

8.9×10

-4
-5
-5
-5

7

3

Field investigation at Kano River embankments

3.1

Field permeability test

Field permeability tests were conducted on an open-cut cross-section on the upstreamside at Kano Rover 8.5k (see Fig. 8) . The bench was divided into three areas: A (outside
the embankment), B (center), and C (inside the embankment). Field permeability tests
were conducted in each area using the following two methods. First is a method by
JGS-1316 using a Marriott siphon (hereafter referred to as the 1316 method), and theother is a method using a water meter with a test hole of the same size as the 1316
method. In the field permeability test conducted using a water meter method, the waterlevel in a test hole is kept constant by adjusting the water flow rate, and the amount ofwater injected is measured using a water meter (hereafter referred to as the WMPT
method).
Fig. 8 shows the positions of the test holes (labeled 1316 holes and WMPT holes). Eachtest hole was 30 cm in diameter and 40 cm deep, and the distance between the 1316 and
WMPT holes was 50 cm. All test holes had the same dimensions, using which both test
methods were performed; however, the test holes were named after the previously performed test method.
For comparison, a series of laboratory tests were also conducted. Test samples werecollected using the same sampling method as that used in the investigation conductedat the Oda River mentioned in the previous chapter. Each specimen was collected using
a single PVC pipe and was used to measure the permeability only in the vertical direction.

Fig. 8. Test site at the open-cut cross-section on the upstream side of the Kano River

8

3.2

Test results

The field and laboratory permeability test results are listed in Tables 3 and 4, respectively. Each table also reports the coefficient of permeability estimated by Creager’s
method using 20 % grain size, namely, D20. In Table 3, the coefficients of permeability
obtained by the laboratory test in areas A and B, which contain rich fine-grain particle
content, are on the order of the 4th to 5th power for both the 1316 and WMPT methods.
On the other hand, the coefficients of permeability obtained from the laboratory test inarea C, which has a rich sand content, are on the order of the fourth power and consistent
with the estimated values based on D20.
Focusing on the difference between the test holes located at points A and B, a slightdifference in particle size can be observed. However, there is almost no difference between the test methods performed on the same hole. Furthermore, even if the WMPT
hole at point C is highly permeable, cannot maintain a steady water level with a Marriottsiphon, and is difficult to measure, the WMPT method can be used depending on the
supply capacity of the submersible pump. We confirmed that the WMPT method isuseful for determining the coefficient of permeability in the field of embankment soil
with a wide range of grain sizes, including coarse particles.
In Creager’s method, the estimated coefficients of permeability differ significantly between the test holes in both areas A and B. This is caused by the large difference in theD20 values owing to the slight increase in the fine grain content of the 1316 holes. For
embankment bodies with fine-grained sandy soil, the difference in the range of finegrained fractions greatly affects the value of D20. Therefore, care must be taken whenusing Creager's estimation method.
In the laboratory permeability test results reported in Table 2, areas A and B with richfine contents had coefficients of permeability of the sixth power order, while area C
with rich sand had coefficients of permeability of the fifth power order. There is almost
no difference in the permeability test results at the test holes in each area. Subsequently,
since there is no difference in D20, there is no difference in the coefficients of permeability obtained using Creager’s method.
Fig. 9 shows the relationship between the coefficients of permeability obtained by Creager’s method, 1316 method, WMPT method, and laboratory permeability test, arranged in double logarithms. The results of the two field test methods, that is, the 1316
and WMPT methods, agree with each other. However, the laboratory permeability test
obtains smaller permeability compared to the field permeability test, regardless of thegrain size. The coefficients of permeability obtained by Creager’s method are smaller
than those obtained using the field permeability test over a wide range of grain sizes
and do not match until coarse sandy soil with D20 = 0.5 mm.
The above results are consistent with those of investigations conducted in various
places by the authors in the past, such as [1] to [4]. Underestimating the permeability
immediately leads to a risky evaluation of seepage properties; therefore, note that thecoefficients of permeability estimated from laboratory tests and grain size should not
be overestimated.

9

Table 3. Field permeability test results.

Point A

Test hole1316
method(m/s)

1316 hole

7.98×10D 20(mm)

Creager(m/s)-57.67×10-50.0136

2.11×10

WMPT hole 1.32×10-4

1.46×10-40.0906

1.42×10-5

5.64×10-5

WMPT hole 1.20×10-4

1.04×10-41316 hole
Point B

WMPT
method(m/s)

Table 4. Laboratory permeability
test results.

5.69×10-51316 hole

3.68×10

WMPT hole

Impossible
to measure

Point C-7

0.0248

6.16×10-7-40.0922

1.48×10-55.49×10-40.4448

5.66×10-4

4.48×10-40.26861.70×10-4

WMPT

JGS-1316

Point A

Test hole

Laboratory
test (m/s)

D20
(mm)

Creager(m/s)

1316 hole

1.89×10-60.0047

2.73×10-8

WMPT hole 2.48×10-6

0.00442.45×10-8-60.00929.30×10-8

WMPT hole 3.79×10-6

0.00768.90×10-8-50.3791

3.96×10-4

WMPT hole 2.32×10-50.34063.01×10-41316 hole
Point B

1.10×101316 hole
Point C

1.82×10

Laboratory

Creager

0.01
0.1
D20 (mm)1

Permeability k (m/s)

1.0E+00
1.0E-02
1.0E-04
1.0E-06
1.0E-08
0.001

Fig. 9. Relationship between 20 % grain size and permeability coefficient.

4

Summary

The coefficients of permeability obtained from the field permeability tests were generally larger than those estimated from the grain size. This tendency was particularly pronounced in the embankment body with rich fine-grained particle content. In addition,
the permeability obtained from the laboratory permeability test was generally lower
than that obtained from the field permeability test. It can be interpreted that the field
permeability itself includes horizontal permeability anisotropy, which is one of the reasons why the value is larger than that obtained in the laboratory permeability test. In
particular, the fact that the field permeability test conducted in this study used a relatively large-diameter and deep test hole, with a diameter of 30 cm and a depth of 40
cm, is considered to be an important reason for reflecting the scale effect of the permeability of the embankment.
In addition, a novel simpler method for conducting field permeability tests using a water
meter is presented in this study.

10

Acknowledgments
The authors would like to express their gratitude to the Chubu Regional Development
Bureau, Chugoku Regional Development Bureau, and Ministry of Land, Infrastructure,
Transport and Tourism for their cooperation in conducting the investigations reported
in this study. In addition, the authors express their sincere gratitude for the financial
support provided by the Japan Society for the Promotion of Science (Grant-in-Aid for
16H04412 and 20H02245).

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