Application of

Integrated Geophysical Exploration

& Dyke Database for Dyke Inspection

T. KOIKE

Project for Building Disaster Resilient Society

in Vietnam Phase-2

Dyke is composed of heterogeneous materials due to the long history of

construction. The deference of materials may become weakness of the

dyke body.

Ant nest and/or the other animal nests also cause weakening.

In view of long life of the dyke, geophysical exploration and compiling

dyke database are necessary.

Ant Nest in the Dyke Damage History of the Dyke, Ca River

INTRODUCTON

材質の密実度の指標となる表面波探査と、透水性の指標とな

なる比抵抗電気探査を組み合わせた評価手法。

下記クロスプロットの左上（低表面波速度、高比抵抗値）は、緩みが生じ透水性が高まっており、浸透崩壊の危険性が高い箇所といえる。

堤防材質データの入手が困難なベトナム国のダム堤体評価（1次スクリーニング等）に適している。

Deference before and after the

earthquake in 2011 (MLIT)

High Risk

Integrated Geophysical Exploration

Integrated Geophysical Exploration is

an assessment technology by

combination of

Surface-Wave Exploration to measure

the compaction degree and

Resistivity Exploration to measure the

permeability of the materials.

The left-upper area of

LOW surface wave velocity and HIGH

resistivity in the bellow cross-plot may

shows loose / permeable degraded

material, where the slope failure risk is

relatively high.

Application into Integrated Geophysical Exploration

The Integrated Geophysical Exploration

method was implemented for safety

assessment of river dykes in JICA TCP

in Bangladesh.

The high risk zone in the each pilot

project site was clearly extracted by this

method.

The result will be utilized for basic

planning of countermeasures such as

waterproof wall.

Out of Dyke

Inside of Dyke

Roof Tier

Foot

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Distance(m)

-14

-12

-10

-8

-6

-4

-2

0

Dept

h(m

)

-14

-12

-10

-8

-6

-4

-2

0

dept

h(m

)

0

20

40

60

80

100

200

300

400

500

Resistivity(ohm-m)

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Distance(m)

-14

-12

-10

-8

-6

-4

-2

0

dept

h(m

)

-14

-12

-10

-8

-6

-4

-2

0

Dep

th(m

)

0.08

0.1

0.12

0.14

0.16

0.18

0.2

0.24

0.28

S-Wave Velocity(km/s)

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100-14

-12

-10

-8

-6

-4

-2

0

-14

-12

-10

-8

-6

-4

-2

0

Distance(m)

Depth(m

)

Depth(m

)

0

100

200

300

400

0 0.05 0.1 0.15 0.2 0.25 0.3

1

2

3

4

＋

2D Resistivity Exploration

Surface Wave Exploration

Result Example of IGE in Bangladesh

Application into Integrated Geophysical Exploration

Inspection Planning for Integrated Geophysical Exploration in Kasumigaura Lagoon (MLIT)

In river management, river bathymetric survey

is also important as well as inspection of river

structure.

The project supported bathymetry survey using

acoustic sounder in the Ca river.

The obtained bathymetry data was combined

with high-resolution Digital Elevation Model

(DEM) as River Geographical Database.

User can extract any cross-sections from the

database.

Bathymetry Survey for Dyke Database

Bathymetry with DEM in Ca river

Dyke Database prepared by UAV

UAV (unmanned aerial vehicle) is also applicable

for Dyke Database in order to obtain wider and

detailed aerial photograph and surface elevation

data set.

The resolution = 2-10 cm, the accuracy < 10 cm.

CIM : Construction Information Model (MLIT)River Photograph

C/P Training in Japan

Application for Dam Safety Management

River Dyke and Earth Dam are basically same structure.

Integrated Geographical Exploration method, and Dyke Database can

be applied for Dam Safety Management in future.