Workshop of nuce(kanno) by xaydung khoinghiep

Introduction of Landslide Disaster Investigations and Countermeasures which are applicated of the Japanese Technology

1.Takami KANNO Dr. Sc 2. Do Ngoc TRUNG Ms. Eng 1.Kawasaki Geological Engineering Co., Ltd , Japan 2. Vietnam-Japan Engineering Consultants Co., Ltd,

CONTENTS OF THE PRESENTATION 1.

INTORODUCTION(What’s Landslide？) 地すべりとは何か？

2．Example of the slope disasters and the countermeasures

for landslides in Japan. 3. CASE STUDY OF LANDSLIDE DISASTER IN VIETNAM ベトナムにおける地すべり災害のケーススタディ 3. RISK ASSESSMENT BY AHP METHOD IN VIETNAM. ベトナムにおけるAHP法を用いた地すべりの危険度評価とハザードマップの適用事例 4. EARLY WARNING SYSTEM USING GNSS ベトナムにおけるGNSSを用いた地すべりの早期警戒システムの適用事例 5. CONCLUSION まとめ Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

What is "Landslide" ?

Cao Báº±ng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

■ What is "Landslide" ?

Crown cracks Crown Main scarp

Head

Lateral scarp Transverse cracks Lateral ridges Radial cracks

Main slip surface Main body Toe of surface of rupture Foot Secondary slip surface

Toe

Cao Bằng Workshop at the NUCEof ,Sep Landslide Fig.1 Schematic Image 30th , 2017 in Hanoi

Reference : http://www.eoearth.org/article/Landslide

■ What is "Landslide" ?

Rotational landslide Translational landslide

Rock fall

Topple Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Block slide

Debris flow

Fig.2(a) Type of slope movement

■ What is "Landslide" ?

Debris avalanche

Earthflow

Creep

Lateral spread

Fig.2(b) Type of slope movement Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in HanoiReference :

http://www.eoearth.org/article/Landslide

Human activities responsible for causing landslides

Signs of landslides

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Example of the slope disasters and the countermeasures for landslides in Japan.

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Countermeasure construction of landslide

Cao Báº±ng Workshop at the NUCE ,Sep

http://www.ktr.mlit.go.jp/river/bousai/river_bousai00000021.html 30th , 2017 in Hanoi

Countermeasure construction of landslide

Cao Báº±ng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Drainage Well

Well Digging

Drainage Drilling

Spring water from drainages Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

http://www.maff.go.jp/tohoku/nouson/kokuei/shon ai-sahi/shintyoku.html

Lightweight Fill (EPS : foamed styrol) Embankment to the head of landslide

Cao Báº±ng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Ground Anchorage

Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi https://www.pref.nagano.lg.jp/xdoboku/chouken/jidukiyama/taisaku.html

アンカー工

Stability Analysis of Landslide in 3D

Case of 3D Stability Analysis , and Ground-Anchor Method for Landslides in The Tunnel-Entrance

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Preventive Piles for Landslide

http://www.kkr.mlit.go.jp/yamato/outline/landslide/stu Cao Báşąng Workshop at the NUCE ,Sep 30thdy/effort01.html , 2017 in Hanoi

切土補強土工

Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

地質的判断の誤りによる設計ミス小規模崩壊として設計した法枠の破壊，地すべり地形及び膨潤性地質の判断及び評価ミス

新潟県佐渡島

Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

補強土壁工ジオテキスタイル工法 PETボトルと同じ材料の繊維でできた紐を並べてできたベルトを格子状に構成したマットを、土の間に何層かに敷き並べ摩擦による引き抜き抵抗力で安定を保つ工法。

Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

多数アンカー工法アンカープレートの引抜抵抗力を利用して盛土を拘束するとともに、壁面に作用する土圧に抵抗して、安定した盛土を構築する。現地発生土（粘性土、砂質土等）を有効利用でき、それぞれに適したフレキシブルな設計が可能。

Cutting head of the landslide

Cao Báº±ng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Case of Landslide Countermeasures Komagome Landslide in Nagano Prefecture ,Central Japan. Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

今回の試作機器

Drainage Drilling on the ground

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Drainage Well：RC-Segment

Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Drilling Core Sampling Tecnology â&#x2013; Core Pack Tube - This is a sampling tube applied to drilling machine. - It is enable to take soil or rock core sampling with a high rate. Sleeve Bit

Sleeve Case

Inner Tube

Outer Tube Reaming Shell

Core Lifter Lifter Case

Drilling as rotating outer tube, but inner tube doesnâ&#x20AC;&#x2122;t.

< Sample of drilling core >

■Soil core (sedimentations)

■Rock core (shale)

Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Automatic Evacuation Warning System in Landslide Hazard Area Measuring instruments and observation system

crack Back crack

Extensometer

Alarm panel Landslide

Pipe strain gauge

Alarm

House

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Automatic Evacuation Warning System in Landslide Hazard Area

Cao Báº±ng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Automatic Evacuation Warning System in Landslide Hazard Area Rain Gage

ＬＡＮ

Internet Communication Module Graph 【Web Browser】

Hub Crack Meter

Data Manager【Web】

Landslide Pip

Alarm Unit AlarmMail

Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Case Studies Mong-Sen Bridge Landslide One of the most highest risk of the landslides along

the National Road Route 4 – Lao Cai

Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Location Map of the Survey Area

About 250km North West of Hanoi

Cao Báº±ng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

【Pilot Project】Design study of landslide countermeasures method

Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Jun.2012

Sep.2004

April.2004

History of the MonSen landslide

Cao Bằng Workshop at the NUCE ,Sep JUN.２０１２ 30th , 2017 in Hanoi

Nov.2012

Analysis of Topographic Features of Landslides by Terrestrial LiDAR Ground Surface Visible!

Superposition LiDAR DEM

Cao Báº±ng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Topographical Map

Preliminary Results of High Density Geophysical Exploration in the MonSen Landslide Resistivity cross-section

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Preliminary Results of Drilling Servey in the Mon-Sen Landslide

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Analysis of Landslide Flow 流下解析（地すべり開始前）

地すべり範囲

国道4D

流下解析（流下後）

国道4D

Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

土砂埋積範囲

Design Study of Landslide Countermeasures Method Drainage drilling work

LEGEND Drainage drilling Ground surface drainage Scarp, Knick line Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Landslide-slope surface protection by log fence

Ground surface drainage

Design study of landslide countermeasures method Drainage drilling work

fault gouge gneiss or granitic bed roks

slip surface

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

gneiss or granitic bed roks

Case Studies Bao Loc district ,Lam Dong Landslides occurred in urban areas

Cao Báº±ng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Bao Loc landslides overview

Fig 2.1-2. Overview of the atLandslide in Bao Loc city Cao Báº±ng Workshop the NUCE ,Sep 30th , 2017 in Hanoi

Bao Loc landslides overview

The result of the terrain

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi using analysis of landslide block

satellite image by google earth

The result of the terrain analysis of landslide block using stereoscopic view of aerial images

Bohole HK01 Position of extensometer

Bohole HK02

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Base Rover

B-1 Rover 02 Rover 01 B-1

Cao Báº±ng Workshop at the NUCE ,Sep The location of 3 rovers 30th , 2017 in Hanoi

Extensor meter

Cao Báº±ng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Installation of the frame with Distance between piles: about 2m

Determination of the position for installation

Setting up the box Fig 2.3-4 (5)~(12). Installation of the extensometer Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

This device is working

Finishing the installation Fig 2.3-4 (13)~(18). Installation of the Cao Báşąng Workshop at the NUCE ,Sep extensometer 30th , 2017 in Hanoi

Case Studies in addition Landslides occurred at urban area in Da Lat ,April 2017

Cao Báº±ng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Toàn cảnh khu vực bị ảnh hưởng tại đường Nguyễn Văn Trỗi (Overview of affected area at Nguyen Van Troi street- Da Lat city urban area)

Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Toàn cảnh vị trí bị trồi lên tại nhà số 100B đường Trương Công Định (Overview of uplift position at house No.100B Truong Cong Dinh street Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Bên trong nhà 100B, có khá nhiều khe nứt và có hiện tượng nước bị chảy tràn lên (Inside this house, there were a lot of cracks and an overflowing position) Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Tại nhà số 94/17 đường Trương Công Định cũng xuất hiện khá nhiều vết nứt (At house No.94/17 Truong Cong Dinh street, there were also a lot of cracks) Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Bên trong nhà, vết nứt chạy dọc theo chân tường và trong khu vực bếp (Inside this house, there were cracks along the wall and in the cooking area) Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Cao Báº±ng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Kết quả khảo sát địa vật lý (Result of geophysical survey)

Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Kết quả khảo sát địa vật lý – Tuyến 1 – Dốc Sông Lô Dị thường

Tuyến 1 dọc theo Dốc Sông Lô, tồn tại dị thường điện trở suất thấp từ cọc 11 đến cọc 15 (từ 50 đến 70m) tới độ sâu khoảng 15m. Lớp điện trở suất cao bên dưới lại có xu hướng nghiêng một phần về dốc cao hiện hữu, tạo điều kiện giữ nước ở phần sườn.

Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Kết quả khảo sát địa vật lý – Tuyến 2 – N.V. Trỗi Dị thường

Tuyến 2 dọc theo đường Nguyễn Văn Trỗi. tồn tại dị thường điện trở suất thấp từ cọc 24 đến cọc 31 (từ 115 đến 120m) tới độ sâu khoảng 20m. Đặc biệt trong tuyến nhìn tổng thể chia thành 02 phần: đầu tuyến đến cọc 21 điện trở suất cao, phần còn lại điện trở suất thấp. Tạo ra bất đồng nhất về cấu trúc dễ tạo ra lún cục bộ ở phần điện trở suất thấp nếu xảy ra hiện tượng ngậm nước và tăng tải. Dị thường này nằm ngay dưới các khu vực đang xảy ra nứt đất. Dị thường này do rò rỉ từ nước máy thấm vào nền đất bên dưới.

Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Kết quả khảo sát địa vật lý – Tuyến 3 – P.Đ. Phùng Dị thường

Dị thường

Tuyến 3 dọc theo đường Phan Đình Phùng, tồn tại dị thường điện trở suất thấp từ đầu đến cuối tuyến tới độ sâu khoảng 20m.

Dị thường này tương đối đồng nhất, toàn tuyến nên có thể khẳng định khu vực này là nơi nước mưa và nước ngầm được giữ ở đây làm đất khu vực này bị nhão, sức chống trượt yếu gây nên trượt chân dốc kéo theo khối trượt dịch chuyển. Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Hiện tại, công ty đã tiến hành lắp đặt 1 bộ dãn kế tại nhà số 27C đường Nguyễn Văn Trỗi (At present, KGE have installed extensometer at house No. 27C Nguyen Van Troi street Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Và 1 bộ dãn kế tại đường Trương Công Định (And at Truong Cong Dinh street) Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Image of the Investigation

Bore-hole with extensometer and water level gauge Electrical Survey Extensometer Drection of Underground water

Báşąng Workshop at the NUCE ,Sep UndergroundCaowater drainage method 30th , 2017 in Hanoi

Cao Báº±ng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Case Studies Landslides occurred in manmade cutting slope along the provincial road DT723

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Cao Báº±ng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Case Studies

Landslides occurred at the manmade cutting in Dien Bien province

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Cao Báº±ng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Landslide Risk Assessment by the AHP Method along the national highway 4D in Lao Cai-Sa Pa

Cao Báº±ng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Analyzing Procedure of Landslide Risk Assessment by the AHP  AHP (Analytic Hierarchical Process) method is one of the methods of “Operations Research” was proposed by T.L. Saaty ( 1 9 7 1 ) .  Step 1:Extraction of the features of the t o p o g r a p h y  Step 2:Extraction of the factors to be applied to risk assessment by brainstorming  Step 3:Analysis of risk assessment by AHP m e t h o d

Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Step1:Topographic Analysis by Stereocopy of Satellite Images

Cao Báº±ng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Extraction of the Landslides Hazard Using Stereocopy of Satellite Images

National Highway Route4 About 30km length investigated

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

1-1 Landslide type which do not show landslide terrain

Landslide that occurred in the gneiss bed-rock that was strongly weathered, Seem to be soil This is man-made slopes (W=15m, l=10m, h=6m)

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

1-2 Landslide type which do not show landslide terrain

Wedge-shaped collapse of the weathered gneiss bedrock This is man-made steep slopes (W=20m, l=20m, h=20m)

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

2-1 Landslide type which show landslide terrain

Weathered bedrock landslide caused by

river channel erosion

(W=70m, l=100m, h=30m)

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

2-1 Landslide type which show landslide terrain

Weathered rock or bedrock landslides caused by river channel erosion (W=80m, l=120m, h=20m)

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

2-2 Landslide type which show landslide terrain

The colluviums landslides occurred behind

that the weathered rock or bedrock(gneiss or granite)

Presence of the fault gouge is assumed This is the man-made slope ,cutting (W=300m, l=500m, h=70m)

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

2-3 Landslide type which show landslide terrain

Circular arc type landslide of horse-shoe shape occurred in strongly weathered bedrock (gneiss or granite) cutting front end of the landslide (W=70m, l=100m, h=30m) Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

2-3 Landslide type which show landslide terrain

Circular arc type landslide of horse-shoe shape occurred in strongly weathered bedrock (gneiss or granite) cutting front end of the landslide (W=500m, l=800m, h=250m)

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

2-3 Landslide type which show landslide terrain Circular arc type landslide of horseshoe shape occurred in strongly weathered bedrock (gneiss or granite) many cracks and many steps exist in road, cutting front end of the landslide (W=100m, l=100m, h=20m)

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Results of Landslide Risk Assessment by the AHP Method

Risk assessment by brainstorming, Scoring landslide risk factors.

Extraction results of 6 factors , as follows.

a. The phenomenon of cracks, steps b. c. d. e. f.

and bulging of the ground. Clarity and presence of the topographic features of landslide Differentiation of the landslide block Clarity of knick line Slope gradient Effect of the river channel erosion

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Creating Hierarchical Model LEVEL1 is 6 factors （a,b,c・・・） and LEVEL2 is each 3 factors （a1,b1・・・）

The first hierachical level LEVEL1

Clarity of Crack,Step, and Bulging of the Ground

Clarity of Landslide Configuration

Differentiation of Landslide

Clarity of Knick Line

The second hierachical level LEVEL2 a1 a2 a3 b1 b2 b3 c1 c2 c3 d1 d2 d3 e1

Slope Gradient

e2 e3

Affects of River Erosion

Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

f1 f2 f3

Large-Scale Phenomenon Exist Small-Scale Phenomenon Exist No Phenomenon Clarity Obscurity Not exist Blocks of four or more Blocks of two or three Single Block Clarity Obscurity Not exist Steep Gradient (more than 60 °) Steep Moderate (20-60°) Gentle Gradient (less than 20 °) Affect Strong Affect Moderate No Affect

Pairwise comparison of the first hierarchy Compare the weight for the determination of each factor A

Factor A is an important factor 20 times compared to the factor C, Or Factor C is an important factor 1/20 times compared to the factor A

C multiplication of the weight ,each factor

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Pairwise comparison of the second hierarchy Compare the weight for the determination of each factor

FACTORS

Steep Gradient (more than 60 °)

Steep Moderate (20-60°)

0.04

Gentle Gradient （ｌess than 20 °）

0.25

0.5

Gentle Gradient （ｌess than 20 °）

FACTORS

Large-Scale Phenomenon Exist

Small-Scale Phenomenon Exist

No Phenomenon

Large-Scale Phenomenon Exist

Small-Scale Phenomenon Exist

0.04

No Phenomenon

0.02

0.04

FACTORS

Clarity

Obscurity

Not exist

Clarity

Obscurity

0.2

Not exist

0.1

0.2

FACTORS

Affect Strong

Affect Moderate

No Affect

Affect Strong

Affect Moderate

0.04

0.1

0.2

Cao Bằng 1Workshop at the NUCENo,Sep Affect 30th , 2017 in Hanoi

Total Scores of Risk Assessment and Hierarchical Structure by AHP The 1st hierarchy a) Clarity of Crack,Step, and Bulging of the Ground

b) Clarity of Landslide Configuration

c) Differentiation of Landslide

The 2nd hierarchy

SCORE2

SCORE1× SCO RE 2 SCOR2

SCORE 1

a-1)Large-Scale Phenomenon Exist

0.854

0.5773

0.676

a-2)Small-Scale Phenomenon Exist

0.135

0.0913

a-3)No Phenomenon

0.011

0.0074

SCORE 1

b-1)Clarity

0.734

0.1879

0.256

b-2)Obscurity

0.209

0.0535

b-3)Not exist

0.057

0.0146

SCORE 1

c-1)Blocks of four or more

0.734

0.0250

0.034

c-2)Blocks of two or three

0.209

0.0071

c-3)Single Block

0.057

0.0019

d-1)Clarity

0.571

0.0091

0.286

0.0046

Analysis score of landslide activity assessments SCORE 1

d) Clarity of

Total score

Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi 0.016 d-2)Obscurity Knick Line

List of Each Locations Landslide Risk Assessment by the AHP Locatio n Type of Landslide Number 1 2 3 4 5 6 7

8 9 10

Weathered Rock Landslides Landslide Configuration Rock Failure Landslide Configuration Landslide of Colluvium Landslide of Colluvium Landslide in Soil of Weathered Rock Landslide in Soil of Weathered Rock Landslide of Colluvium Weathered Rock Landslides

a) Clarity of Crack,Step, and Bulging of the Ground

b) Clarity of Landslide Configuration

c) Differentiatio n of Landslide

d) Clarity of Knick Line

e) Slope Gradient

83.0

8.6

82.4

6.3

12.7

84.8

64.3

83.0

82.5

f) Affect of Evaluation Score River Erosion by AHP

■65p over : risk large（red） Cao Bằng Workshop at the NUCE ,Sep ■65-20p : risk midium(orange) ■20p under : risk small (green) 30th , 2017 in Hanoi

Results of Landslide Hazards Risk Assessment Map Theby landslide risk assessment AHP Method (30km) map along the National Highway 4

Cao Báşąng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Early Warning system

using GNSS at the urban area in Bao loc

Cao Báº±ng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

The location of the GNSS system Base Rover

B-1 Rover 02 Rover 01 B-1

Cao Báº±ng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Extensor meter

Cao Báº±ng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Conclusion Applying Japanese technology such as landslide risk assessment by AHP method and early warning system using GNSS in Vietnam.

■Suggest the importance of disaster prevention and mitigation,

that should takes some measures before the serious damages will occur . ■ As a method for the landslide hazard risk assessment quickly

and widely carry out, the AHP method is a means effective and economical in Vietnam

I sincerely wish for the development of landslide technology in Vietnam, and our technology will contribute to the safety and security of Vietnamese peoples. Cao Bằng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi

Thank You for Your Kind Attention!

Presented by Takami KANNO

Kawasaki Geological Engineering Co., Ltd. Cao Báº±ng Workshop at the NUCE ,Sep 30th , 2017 in Hanoi