Major Coastal Engineering and Management: Designing structures to protect embankment at the economic zone of Nam Dinh Vu - Hai Phong

Bạn đang xem bản rút gọn của tài liệu. Xem và tải ngay bản đầy đủ của tài liệu tại đây (3.97 MB, 94 trang )

<span class="text_page_counter">Trang 1</span><div class="page_container" data-page="1">

MINISTRY OF EDUCATION MINISTRY OF AGRICULTURE AND TRAINING AND RURAL DEVELOPMENT

THUY LOI UNIVERSITY

VU THI HIEN

DESIGNING STRUCTURES TO PROTECT

EMBANKMENT AT THE ECONOMIC ZONE OF

MASTER THESIS

HANOI, 2018

</div><span class="text_page_counter">Trang 2</span><div class="page_container" data-page="2">

MINISTRY OF EDUCATION — MINISTRY OF AGRICULTURE. AND TRAINING AND RURAL DEVELOPMENT

‘THUY LOI UNIVERSITY

VU THI HIEN

DESIGNING STRUCTURES TO PROTECT EMBANKMENT AT THE ECONOMIC ZONE OF

NAM DINH VU - HAI PHONG

Major code: 6258023

SUPERVISOR: ASSC. PROF, PHD. LE XUAN ROANH

HA NOI, 2018

</div><span class="text_page_counter">Trang 3</span><div class="page_container" data-page="3">

With proposal: “Designing Structures to Protect Embankment at The Economic Zone of Nam Dinh Vu ~ Hai Phong”.

Thereby declare that is the researched work by myself under the supervision of Assoc. Prof. PhD. Le Xuan Roanh, The results and conclusions of the thesis are fidelity, which are not copied from any sources and any forms. The reference documents relevant sources, the t sis has cited and recorded and prescribed. The results of my thesis have not been published by me to any courses or any awards, I declare that the information provided in this document is correct and assume full responsibility for any untrue or incorrect information.

Hanoi, May date 2018 Author of the thesis

Vu Thi Hien

</div><span class="text_page_counter">Trang 4</span><div class="page_container" data-page="4">

With the effort of myself and teacher's help, colleague, friends and family, the

graduation thesis on “Designing Structures to Protect Embankment at The Economic

Zone of Nam Dinh Vu ~ Hai Phong” have been completed

Firsily, let me express deep gratitude to Assoc. Le Xuan Roanh has guided me ‘wholeheartedly during the research, research and implementation of this thesis.

1 would also like to express my sincere gratitude tothe teachers in Marine

Engineering Faculty - Water Resources University for giving me more time to help me finish my dissertation

‘Thank to my family, friends and colleagues who have facilitated and helped me throughout my studies and research. Thank you very much!

</div><span class="text_page_counter">Trang 5</span><div class="page_container" data-page="5">

3... Objects and scope of the wtudy,... so = 3 4. Study approaches and methodology. 3 5S. Expected results on so so = 3

CHAPTER | OVERVIEW ABOUT PROTECTED SEADIKE AND

‘CONSTRUCTED EXPENSIVE METHODS 5

_-1.1.1 Concept about sea-dike, 5

1.1.2 Concept about embankment : : _

1.2 Research on dike structure in the world and in Vietnam, 7 1.2.1 Researches of sea-dike in the world.

1.2.2 Researches of sea-dike in Vietnam 10 1.3. Basic types of dike cross sections, structures and materials to form sea dikes 13 1.4 Proposing of cross-section selection 16 1.4.1 The proposed research plans... „16 1.4.2 The plan analysis 20

</div><span class="text_page_counter">Trang 6</span><div class="page_container" data-page="6">

2.1 Natural features of the Sty’ ared... 2.1.1 Geography and terrain

3.12 Wind mode

2.1.3 Hydrographical characterises 2.144 Oceanographical regime: 2.1.5 Wave regime.

2.2 Simulating the development of Nam Dinh Vu new economic Zone... 2.2.1 Introduction about MIKE 21 model

2.2.2 Collected documentation 2.2.3 Model setup

2.24 Hydrodynamic simulation resils... 2.3 The chapter conclusion

CHAPTER 3 DESIGN AND STABILITY CALCUALATION OF DIKE STRUCTURE 45

3.1 Selection of design boundary condiions.

3.1.1 Geological and terrain condition related to design 3.1.2 Design of dike cross section

3.2 Hydraulic stability of armour layers 3.2.1 The thickness of armour layer

3.2.2 Structure stability calculation of box concrete

3.3 The structural ve on the berm and toe dike (erosion holes) 3⁄4 The stability of armour layer with ABAQUS software

3.4.1 Introduction about ABAQUS software 34.2 The model and structure analysis...

</div><span class="text_page_counter">Trang 7</span><div class="page_container" data-page="7">

3.5 The chapter conclusion

CONCLUSION AND RECOMMENDATIONS:

</div><span class="text_page_counter">Trang 8</span><div class="page_container" data-page="8">

LIST OF FIGURES

Fig 1.1 Cat Hai - Haiphong zone is protected by sea-dike 5 Fig 1.2 A picture showing the formation of a dike using clay slurry filled geotextile ..8 Fig L3 Mlustration of the prefabricated caisson supported by a rubble mound and source protection cover. 8 Fig 1.4 Installation of upper cylinders to form breakwater 9 Fig 1.5 Homogenous dredged material dike with geosynthetic drainage composite... 9 Fig 1.6 Sensor data from seepage test in crass. <small>ection</small>

Fig 1.7 Maximum velocity at the sea edge of the crest dike depends on overtopping volumes of a wave; with the cases Hs =1,5m; Tp 6s; tana=0,25. in Fig 8 Wave overtopping simulator is tested at Tien Hai — Thai Bình dike "

Fig L9 Prefabricated structure protects rivers and sea dike n

Fig 1.10 Prefabricated structures protect river and sea dike 2 Fig 1.11 The section shapes of the sea-dike “ Fig 1.12 Rock on seaside slope, sheet piles under embankment. 16 Fig 1.13 The gentle slope, protection of the roof with two layers of stone, the use of ‘geotextile on ground. 16 Fig 1.14 Steep slope, using hollow box to reduce load 1 Fig 2.1 Haiphong coastal estuary and Bach Dang estuary 2

Fig 2.2 Domain topography of zone. 31

Fig 2.3 Computed gird, 31

Fig 2.4 Compared results between actual and computed flow velocities 33 Fig 2.5 The water level line between observed water level and computed water level at Hon Dau station 03/2009 34 Fig 2.6 The flow field in Haiphong estuary mouth among the high tidal phase - in the dry season 37

VỊ

</div><span class="text_page_counter">Trang 9</span><div class="page_container" data-page="9">

Fig 2.7 The flow field in Hai Phong estuary among the low tidal phase ~ in dry season Fig 2.10 The velocity process line in the study area 39 Fig 2.11 The flow direction inthe study area 40 Fig 2.12 The maximum velocity inthe dry season “ Fig 213 The maximum velocity inthe rainy season 2 Fig 2.14 The wave height of South with 26 frequency design 4 Fig 2.15 The wave height of Est with 26 frequency design 43 Fig 3.1 Synthesis frequency line in Dong Hai, An Hai, Haiphong city at No.9 section

(106"48°, 20°48") 50

Fig 3.2 Tie structure with drainage holes 5 Fig 3.3 Precast concrete constructions Busadco Productions 55 Fig 3.4 Typical cross-section of dike 5 Fig 3.5 The calculation chart of friction force to hold structure (toe dike) 62 Fig 3.6 The relationship between velocity and bulk material load protecting the toe

‘embankment. 68

Fig 3.7 The largest erosion depths in the breakwater has a protective layer (Summer and Fredso, 2001) oo Fig 3.8 The model of 7 block has 5.0m height in ABAQUS m Fig 39 The loading chart works on the conjugate embankment according to the formula of Takahashi and Hosoyamada. T2 Fig 3.10 The calculated loading due to wave action on embankment 7 Fig 3.11 The boundary condition and the loading n Fig 3.12 The stress distribution von Mises, MPa. 14

</div><span class="text_page_counter">Trang 10</span><div class="page_container" data-page="10">

Fig 3.13 The stress distribution von Mises, Mpa

Fig 3.14 The contact distribution among the face of block, MPa Fig 315 The stable settlement

Fig 3.16 The work load q = 2T/m?

Fig 3.17 The modeling meshing

Fig 3.18 The vertical displacement of the whole system Fig 3.19 The vertical displacement of the whole system Fig 3.20 The vertical displacement of the whole system

</div><span class="text_page_counter">Trang 11</span><div class="page_container" data-page="11">

LIST OF TABLES

‘Table 1.1 The projects are arranged by the structure for Nam Dinh Vu dike 18 ‘Table 2.1 Frequency of wind velocity and annual directions at Hon Dau (1960 - 2011)

lò) 24

‘Table 2.2 Frequency of wave heights and directions at Hon Dau (1970 -2011) [8]....27

Table 3.1 Determining the chemical compositions of water 47 ‘Table 3.2 Safety standards coresponding tothe work level [7] 48 Table 3.3 The width ofthe dike crest according to the work level 49 ‘able 3.4 The results of wave height calculation to protect sea-dike [7Ì si Table 3.5 The selected options 56 ‘Table 3.6 The stability coefficient of embankment. 39

Table 37 Friction coefficient ft 6

able 3.8 The outer trietionforee of eonerete box (FI) 64 Table 3.9 Frietion force ealeulation (F4) 64 Table 3.10 The fiietion force ofthe pile, one box has two piles (0.3°0.3m pile area and im depth) 6 ‘Table 3.11 The ficion force with 02*0.2m pile area and 8m depth 6 ‘Table 3.12 The calculated result for 3.5m height and 1.3m depth foot plug of the box site 66 Table 3.13 A stone mass to protect toe embankment following Vax o Table 3.14 The stable settlement 76

</div><span class="text_page_counter">Trang 12</span><div class="page_container" data-page="12">

INTRODUCTION 1, The necessity of study

Vietnam has a coastline of about 3,260 km; the protection and exploitation of marine

economic potential are always associa od with the existence and development of the country. At the same time, the implementation of the above objectives is the development of more and more quantity the greater the seale and rich diversity of functions for marine structures. Among their works such as: coastal protection

structures, storms of shelter-works, harbors, breakwaters, works of protected island,

harbors and airports on distant islands... have been studied and built in the world and Vietnam, Now, due to the demand for construction of seaports, storm of shelters as well as shoreline of protected requirement, the construction of sea dikes is receiving and developing, However, due to the particularity of underwater construction, especially in seawater conditions, the challenges are given to select a protected structure of dike which can be affected of waves, winds, current, slip, anti-structure, landslides, erosion and anti-tide of the marine environment, low investment cost, reducing volume of construction, high project life is a top priority for designers and constructors of marine. Therefore, the content of the topic: “Designing Structures 4o Protect Embankment at New Economie Zone of Nam Dinh Vu ~ Haiphong” is being invested to develop maritime economy. This project is one of the necessary

issues today to become a key economic zone, multi-sectors with mainly field to

develop maritime economy. 2. Study objectives

Dinh Vu - Haiphong economic zone is place where it is exploited about the maximum,

advantage of natural conditions, geographic location, socio-economic potentiality. According to the master plan approved by the Prime Minister with the heart of Haiphong international gateway harbor, it is determined to attract investments and receive advanced technology and to create a new driving force for Haiphong and

North Coast accelerated development.

</div><span class="text_page_counter">Trang 13</span><div class="page_container" data-page="13">

“The Government has directed the construction and development of Dinh Vu - Cat Hai ‘economic zone into an integrated economic zone, a marine economic center, multi-sectors, including maritime economy (Which a major is serviced development of harbor), industry, finance, banking, tourism and trade center of the region and the whole country. Dinh Vu — Cat Hai economi <sub>zone is built and developed by</sub> evelopment planning of Haiphong city and the Northern major economic zone and ‘wo economic corridors: Con Minh (Lao Cai Lao Cai) Hanoi Haiphong -(Quangninh; Namninh (China) - Lang Son - Hanoi - Haiphong - Quangninh; which create closed links with Van Don - Quangninh economic zone. In the immediate future, Dinh Vu - Cat Hai economic zone will focus on developing high-quality resorts (Cat Ba cco-tourist resort, Nam Trang Cat tourist resort, green paks — entertainment...), a modem seaport system with a total natural land area of 1,046ha

(Tan Dinh Vu, Nam Dinh Vu, and Cat Hai harbor, International harbor Gate of

Haiphong, ..) tariff zone 12,532ha, non-tariff area 1,258ha, ueasure system about 209ha, industrial parks with total natural land area

Ben Rung 698 ha, industrial zone of VSIP , industrial zone of Trang Cat 138ha,

550ha (319haindustrial zone of

industrial zone of Nam Dinh Vu 681ha, industrial zone of Cat Hai and Lach Huyen istrict 4444ha, Trang Duc industrial park 400ha, public service centers 761ha, specialized centers 2.105ha, urban areas and urban population 2.062ha, land of national defense ~ security 103 ha...

In the sea-oriented strategy of Viemam's economy, Dinh Vu Economic Zone was invested to become a modern deep water economic zone in the North. This economic zone serves as a trading gateway for the whole of the North. The information and

evelopment of economic zone have marked a development of Viet Nam maritime

‘economic zone. [1]

‘Therefore, the purpose to build the Nam Dinh Vu dike is to expand the area of the industrial zone and to protect the anti-wave seawall protection in marine economic ‘zones or ship and boat refuge areas when there is a special storm in the embankment to

protect against storm waves according to design frequency.

</div><span class="text_page_counter">Trang 14</span><div class="page_container" data-page="14">

3. Objects and scope of the study

‘The study is limited in scope of Nam Dinh Vu dike, which focuses on specific cireumstances in Dong Hai and Trang Cat areas.

4 The object of the study is to design and study deep dike protection structures that

can withstand the effects of waves, winds, undercurrents, anti-slip, anti-ft<small>racture,</small>

landslides, corrosion and anti-erosion, sea environment erosion, low investment cost, reduced construction volume, high life expectancy for the new economic zone Nam Dinh Vu - Haiphong.

4. Study approaches and methodology

<small>- Collected documents, geological and hydrographical data to determine hydrological</small>

border of Nam Dinh Vu new economic zone.

- Based on shoreline developments to design sea dike protection structures.

<small>~ To calculate the stability of the building which was designed,</small>

5. Expected results

‘The limit in the framework of Master thesis, the expected results include: + To have overview of the design dikes;

+ To propose some design options which can be applied by a new economic Nam Dinh Vu zone and analyses and select structural solutions for the selected plan.

+ To calculate the stability of the design 6. Structure of thesis

Besides the introduction, conclusion, recommendation and annexes, the study is consisted 3 chapters as following:

</div><span class="text_page_counter">Trang 15</span><div class="page_container" data-page="15">

Chapter1: Overview about protected sea-dike and constructed expansive methods Chapter 2:

Nam Dinh Vu Zone.

pplication of MIKE21 to determine calculated hydrological bounds of

Chapter 3: Design and stability structures to protect sea-dike.

</div><span class="text_page_counter">Trang 16</span><div class="page_container" data-page="16">

CHAPTER1 OVERVIEW ABOUT PROTECTED SEADIKE AND

CONSTRUCTED EXPENSIVE METHODS,

1.1 Concept about sea dike and embankment

ILL Concept about sea-dike

Sea-dike is formed from structures that prevent tides, reduce wave run- up and sure

‘wave to be coastal stabilization, bays and estuaries, and protect the livelihood and

economic zones within the shoreline land for reclamation or aquaculture land,

Sea-dike can be classified by building materials, the belt protected Sea-dikes, water depth

before the dam, the sectional shape of dike.

1.1.2 Concept about embankment

‘Marine embankments are formed works which protecting river bank, coastline from

the effects of erosion caused by currents and waves and are designed in the dike to resist anti-erosion shore materials, dike under the effect of wave and flow.

</div><span class="text_page_counter">Trang 17</span><div class="page_container" data-page="17">

Coastal Vietnam is one of the areas where is the potential land for development of agriculture, forestry and fisheries, including many highly valued tropical ecosystems such as mangroves, seagrass beds, rapids, coral reefs, estuarine areas, tidal flats and

te natural res

other wetland ecosystems. The diver murces are combined with urban and

tourism s

stems. Coastal services are the important advantages and impetus in the

process of socio-economic development of provinces, regions and the whole country ‘Therefore, the expansion of the coastal area is noted by the government and the state eoneerned for the purpose of potential economic development for the country. In addition to the potential development of land for tourism development, the services are interested in the potential land for seaport development.

‘The Red River Delta is formed by important inland waterways along with 20 major

Ports and cargo handling points along the rivers in the provinces in the region,

contributing to the development about social economy of country. In the area, there are some depth water areas suitable for the development of deep water wharves such as Lach Huyen port - Haiphong. To bring into full play the advantages of many types of submerged land and estuarine wetlands, which are favorable for the construction and development of seaports, it

seaports in Cai Lan such as Cai Lan (Cam Pha), Cua Ong (Bai Tu Long bay), Hai

<small>nei</small> sary to focus on upgrading and expanding existing

Phong port, ete .. Invest in constructing general ports at Nha Mac lake, Bach Dang, river port and Chanh river port (Hai Phong).

‘There are many important seaports such as Da Nang, Tien Sa, Lien Chieu (Da Nang), Ky Ha (Quang Nam), coastal ports in the South Central coastal region... creating seaport systems for economic development, The region forms the main artery of the

sea in the world,

‘The coastal areas of the Mekong Delta also have seaport systems such as My Hoa, Tra Vinh, Hon Chong, Ham Ninh... The exploitation of seaports and shipping is also the marine economic advantages of this area, [2]

</div><span class="text_page_counter">Trang 18</span><div class="page_container" data-page="18">

1.2 Research on dike structure in the world and in Vietnam 1.2.1 Researches of sea-dike in the world

Sea-dikes have been established from the longest standing in marine countries to

protect the land inside from floods and natural disasters. There are depended on natural

conditions and development levels of each country, sea-dike systems have been developed by varying degrees. Works of dike structure including revetments, sea walls, breakwater walls, groin systems... were built in order to prevent erosions, sediment transports, sediments at in areas with high risk. Erosion phenomenon is usually swirled in to the deep dike. Therefore, the designed and collected materials to protect sea-dike must be suitable with natural condition of each zone and they are one Of the important factors to protect dike and land inside. And this is one of the issues that the scientists are studying, esearching about structures to protect sea-dike which structures work both to ensure the impact of wind waves, currents, high life expectancy and (0 save on investment costs,

In the past, the most commonly used dike protection structures were prefabricated by

stones or coneretes. With the development of country, the problems of global warming

are leading to sea level rise, increasingly severe natural disasters so inevitability of coastal protection structures are also studied improvements. In recent years, global warming has caused the sea le cl rise. Therefore, the coastal protection structures were also investigation by J. Chu, Yan and Li scientists. As one of the counter measures, some of the ting. coastal protection structures need to be rehabilitated and new, stronger or taller coastal structures have to be built. Three modern types of coastal

protection structures are classified which structures are used, applied and based on

materials to build dike based on advantages and disadvantages of each type of structure. Three structures are the geological buffer structures, the precast concrete structures and the straw structures, [3]

Geologically-cushioned construction agrees with dike and breakwaters in shallow waters, Thi ructure is made up of several layers of thin geologically arranged cascades that overlap each other, which can be sandbags or clay.

</div><span class="text_page_counter">Trang 19</span><div class="page_container" data-page="19">

Fig 1.2. picture showing the formation of a dike using clay slurry filled geotextile Concrete structures suitable for breakwater in uneven areas that was prefabricated. If

the weak ground can be reinforced by rubber cushions.

Fig 1.3 Illustration of the prefabricated caisson supported by a rubble mound and

source protection cover

‘Tubular structure is a new structure but very promising success. Its suitable for deep

<small>water areas.</small>

</div><span class="text_page_counter">Trang 20</span><div class="page_container" data-page="20">

Fig 1.4 Installation of upper eylinders to form breakwater

In addition to concrete materials, grasses are also a very good material to protect the

dike if they were combined with the use of synthetic geotextiles. Stefan Cantré and

Fokke Saathoff have also found dike protection materials given from sedimentation ‘process at estuary zones through combining buffer layers by synthetic techniques and dike roof is covered by grasses. The model was tested by lab and experimental proof in Germany and Poland. The authors showed that materials were used from sediment and

dredging process in the river deltas to build embankments. The authors also showed

that synthetic materials make to increase the drainage process at dike toe and reduce the infiltration in the dike and no permeability at dike roof.

Fig 1.5 Homogenous dredged material dike

‘with geosynthetic drainage composite Fig 1,6 Sensor data from seepage test

<small>in eross-seetion</small>

</div><span class="text_page_counter">Trang 21</span><div class="page_container" data-page="21">

sediment from the Therefore, If we use the material from the dredging process,

estuarine zones combined with synthetic material cover with grass layers, dike will be more durable. [4]

1.2.2 Researches of sea-dike in Vietnam

Vietnam has more than 3,200 km coastal line, which is considered one of the countries mostly influenced by climate change and directly impacted from sea level rise such as seawater intrusions, coastal erosion, erosion at landslides of large rivers, degradation

of forest protection throughout the territory. The corstruction of the protection of

banks, yards, rivers, lakes and seas is a diffi It task, complex, long, large capital needs. Especially, our coastal areas are playing a very important role in the national economy and consolidate security and national defenses. With the help of science and technology, the sea dikes are increasing strength today, becoming the fortification of

‘human life. The stability of the sea dike is a very interesting issue in the context of

current climate change and sea level rise. Therefore, the design of the works towards the less investment goal to bring high efficiency which creates a wave breaking green wall being one of the most problems of the Party and government focus. Therefore the stability of dike protective structures is the most important design and construction content of sea dikes which are vital parts of the building. There are many types of dike protection structures that have been studied by scientists such as: grass plantings,

turtlenecks, anhydrides, stone carpets, prefubricated conerete components, cast

<small>‘concrete components.</small>

‘There is based on the phenomenon of breaking waves and created waves over the dike. “The “wave overtopping simulator, a device to test the grassed dike slopes in situ” Le Hai Trung, etc all... The purpose of test is simulating waves in a specified storm over the dike through discharge overtopping averages q unit length in order to study the stability and failure mechanism of the top and roof dike at land inside under the effect of wave overtopping. The amount of wave overtopping was depended on the boundary conditions of the waves which were calculated by TAW (2202) ~ the 2% wave run up

</div><span class="text_page_counter">Trang 22</span><div class="page_container" data-page="22">

to determine the percentage of wave overtopping at a certain height according to the

According to coefficient C,„` =1,37 and 1,3 ; c„;`=0,33 and 0,15

‘Theoretically, the average discharge overtopping is 10; 20; and 40 Ws/m at the sea edge

of the crest dike with the same volume of a wave overtopping as similar velocity.

‘According to the experiments on the discharge machine, different average wave overtopping for similar velocities to the same volume of a wave overtopping with ‘overtopping flows of 10; 20; and 40 l/e/m at the sea edge of the dike crest,

Fig 1.8 Wave overtopping simulator is tested at Tien Hai ~ Thai Binh dike

</div><span class="text_page_counter">Trang 23</span><div class="page_container" data-page="23">

‘There are many studies on stability of the dike that are applied in the fact. Today, PhD Hoang Duc Thao -Ba Ria ~ Vung Tau ~ Urban Sewerage and Development Company Busadeo has been selected by one of the ten highlight events about science and

technology in 2015. This is a new event which authors invented and put into

application in some provinces such as Thai Binh, Ho chi Minh city, Ba Ria ~ Vung Tau province under the accrediting Technical Center for 3 Quality Measurement standard. [6]

Fig 1.10 Prefabricated structures protect river and sea dike

‘The technical design of the dike in Nam Thinh - Tien Hai - Thai Binh has been presented and the technical parameters about the size of the structure, reinforced cconerete piles, structural loads, capacity of piles ... And the work stability, stability of the structure is calculated by technical standards of sea dikes and have been of the accrediting Technical Center for 3 Quality Measurement standard

‘The method about “putting together structures to protect shoreline and the sea dike” is applied in the constructions of preventative landslide, erosions, breakwaters, wave reductions and embankment, the lands fund development, responding to sea level rise,

</div><span class="text_page_counter">Trang 24</span><div class="page_container" data-page="24">

reinforced, repaired, renovated and upgraded damaged coastal protection works, or investments in new constructions. Construction progress is only 1/3 of the time compared with traditional solutions which overcome weathers, climates and hydrological remedies which are the convenient for operations, maintenance and maintenance. It can also reduce at least 20% investment costs by comparing to traditional solutions, easy to operate and low cost of operation. The high life expectancy leads to be durable durability, not must be to invest many times a construction item and is appreciated in many localities. [6]

Basic types of dike cross sections, structures and materials to form sea dikes

Based on the TCVN 9001-2014 design standard about sea dike to design cross s and sea dike structure based on the geometric characteristics of dike roofing in the the dike section was divided into three main types: embankment, standing wall, and mix dike (on the downside or upside down).

</div><span class="text_page_counter">Trang 25</span><div class="page_container" data-page="25">

Fig 1.11 The section shapes of the sea-dike

Embankment by homogeneous soil: the shape of embankment is usually the trapezoid )23,0 al the land inside, .025,0 at the seaside and m:

and roof dike commonly m

body dike is made by pack soils. Materials are used in structure of homogeneous dike

‘here there are pack soils t0 cover the construction embankment. In the case of low

dike height (dike height less than 2m) can be used in the form of section as shown in Fig 1.11a. With dikes which has poor geological conditions, if the height of dike is large and effected by the wave, it can be arranged the berm at downstream dike and dike berm is used to reduce waves such as fig 1.11.

Slope dike with mixed materials: If the soil reserves of local are not enough to build dike by homogenous materials, the soils are taken away from embankment; while the local materials have a large permeability and very diversity, the soils have a large

</div><span class="text_page_counter">Trang 26</span><div class="page_container" data-page="26">

permeability arranged inside dike body, with a small permeability covered outside dike as shown in Fig 1-1¢ or rocks are arranged at upstream to fight the sabotage of the waves, the soils are covered at downstream as g Ld.

Seawall and combined slope dike: The area is built by the sea-dike construction which hhas a mine soil but reserves of soil are not enough to cover the dike, If using the structure of the standing wall with stones or coneretes, reinforced concrete materials is usually stable, complex, and expensive. Moreover, many construction dikes are not only prevented flooding during high tide but also combined to make the place of resident boat, carriage of goods, top of the dike must have to traffic road. Therefore, the design has to use the structure of stone wall together with soil dike as Fig L.IIe; the concrete walls and the body of soil dike Fig 1.11f or the body of mix soil dike,

concrete wall and wall foundation to make by mix stone Fig 1.11g

Slope dike with geotexles: In many cases, the place doesn’t have strong soil to built ike, it will be used this material on weak soil (small adhesive forces and small corner friction, small permeability coefficient). If the dike uses traditional technology, the dike section is very large with that used materials to make embankment, the area of

ike is very large and construction time is long due to the subsidence, and it make to

increase the cost of constructions. The method geotextile reinforcement to overcome that problems such as reduce the cost of construction, reduce the area of dike, increase construction time. Fig 1. 1h is a geotechnical fabric layout in the dike body. [7]

Based on the analysis of the dike section and the structures of sea-dike protection on cach dike, there are other advantages and disadvantages. The choosing type of cross section must be based on geological topographies, hydrographical conditions,

construction materials, construction conditions and used purposes of the study area

Where the author proposes the dike form to be selected.

</div><span class="text_page_counter">Trang 27</span><div class="page_container" data-page="27">

1.4 Proposing of cross-section selection 1.4.1 The proposed research plans

Nam Dinh Vu dike project was started since 2012 and was approved by the investment ‘managements from the plans as following:

- PAL: Using a traditional protector method as rocks, very gentle slope and ‘combining sheet piles to prevent sliding formation.

Fig 1.12 Rock on seaside slope, sheet piles under embankment

<small>- PA2: Using fill stones with double layers by CMC</small>

Fig 1.13 The gentle slope, protection of the roof with two layers of stone, the use of _geotextile on ground

</div><span class="text_page_counter">Trang 28</span><div class="page_container" data-page="28">

<small>~ PA 3: Consultant recommends lightweight hollow structural components,</small>

Advantages and disadvantages of the three options are summarized in the

following table:

</div><span class="text_page_counter">Trang 29</span><div class="page_container" data-page="29">

‘Table 1.1 The projects are arranged by the structure for Nam Dinh Vu dike

Project Advantages Disadvantages Cost prices

PAL | + Using locally available materials + High Cost 3.248 billion “+Ability to reduce wave height + Use normal construction equipment

+ Construction is dominated by weather i

+ Reduced erosion in front of the structure Construction is dominated by weather, it

takes alot of time

+ Distributed energy through breaking waves + Difficult to maintenance

+Safety in construction work + Difficult to control the quality of earth

+ Suitable for weak geology (s works

PA2 | + Using locally available materials + High Cost 2.792 billion + Ability to reduce wave height by raft

+ Local erosion prone + Easy maintenance

+ Reduced erosion infront of the sưuetire + Suitable for weak soil geology

+ Complex construction is affected by the

</div><span class="text_page_counter">Trang 30</span><div class="page_container" data-page="30">

+ Surface roughness, wave height wil be reduced

PA3 + Structures to withstand the impact of waves, wind, | + This technology solution is suitable only | 2.297 billion

‘underground flow for shallow water, soft soil and mudflats

+ To ensure anti-corrosion and anti-invasion marine

environment (use fiber reinforced concrete)

+ Structure of synchronous system: blocks, pillars, gravity to stabilize

+ Convenient in produce, installation according to the

specific requirements of each region,

+ To control the quality of products before sending out; + Cost of construction investment is lower than traditional solutions;

+ American work compact, clean beautiful; + Life expectancy is high;

+ Convenient for maintenance and management;

+ Suitable for soft soil foundations,

</div><span class="text_page_counter">Trang 31</span><div class="page_container" data-page="31">

1.42 The plan analysis

From analysis above the dissertation to choose option 3 by the following

Due to landside and coastal erosions in the area of coastal Vietnam are increasing by now. This issue greatly affects the economic, environmental and social welfare, The result of dikes as well as coastal proteetion structures have not only played an important role in preventing floods but also reduced the damage natural

disasters caused by floods and particularly protected the safety of large residential

areas which stretch along the rivers and lakes from the North to the South, In the past, these works were mostly designed according to traditional solutions which were severely damaged and didn’t meet the technical requirements. The protection of banks, yands, dikes, sea encroachments, the development of land funds, the strengthening of

protections, stabilization of ecological balances, and overcoming the disadvantages of

natural conditions: Topography, geology. hydrography and navigation. It is necessary {0 improve, innovate and develop new technologies in order to replace the traditional solutions, Today, due to the development of science and technology, shoreline reinforcement protection works have gradually been replaced by stone carpels or ‘concrete slabs, The proposed dike cro section is designed by Busadco Company applied to dike embankment protection. Because assembled structures protect the river, lake and sea-dike -Busadeo” are new structures, guaranteed the technical requirements, applied in construction works against landsides, erosions, breakwaters, reduction of waves, replacing embankment foot and retaining wall, creating shore, ike encroachment sea, development and land funds, response lo sea level rise, reinforcement, epaits, renovation and upgrading of coastal protection works, degraded ‘or invested in new construction. Construction progress of this technology is only one per third of the time compared with traditional solutions. It is necessary to overcome the disadvantages of weathers, climates, hydrology, inconvenient for operations,

maintenanc xvicing, moving, and reusing to expand, This solution also reduces at least 20% investment costs compared with traditional solutions, easy to operate and

ow cost of operation management, Otherwise, these structures also bring high life

</div><span class="text_page_counter">Trang 32</span><div class="page_container" data-page="32">

expectancies to make a long-term durability, not have to invest many times about @ construction item and by highly appreciated in many localities.

1.5 Conclusion of chapter

Reclamation and sea encroachment are the long -term works of our people to expand the land area for economic developments in coastal area and to protect the residential, economic and cultural areas.

ince ancient times of our father are recognizing that is

an importance so they were especially very interested in dike construction of sea dike. And the embankment of sea dikes must be made in difficult conditions due to weak ‘geological conditions, tidal waves, and frequent tides. When science and technology have not developed and introduced in our country, appearance of traditional dike is the same as an indispensable law. Traditional dikes are covered with local materials which are still very existence and can only stand with 9 level of storm and combination with high tides. With the current complicated weather conditions, the traditional dike ‘becomes an obsolete and no longer the requirements about using functions so new structures of dike must appear to respond the demand of that reality. Currently, many moderns and sustainable dike sections have been proposed, researched and app! dịn many parts of the world. The analysis and assessment of the sea dike constructions in the world and in our country play an important role and a precondition for researching and proposing major structural solutions in construction of sea dike in Nam Dinh Vu ~ Haiphong economic zone

</div><span class="text_page_counter">Trang 33</span><div class="page_container" data-page="33">

CHAPTER2 MIKE21MODEL APPLICATION TO DETERMINE. CALCULATED HYDROLOGICAL BOUNDARY OF NAM DINH VU

ECONOMIC ZONE 2.1 Natural features of the study area

2.1.1 Geography and terrain

‘The study area is located in about 20.5 -20.9 the North latitude and 106.5 -107.1 the East longitude, the West coast of the Gulf of Tonkin, the Northeastern margin of the Red River delta of Haiphong city about 102 km the East of Hanoi (Fig 2.1)

Fig 2.1 Haiphong coastal estuary and Bach Dang estuary

(Source: Imagery from Google earth)

This area is made up of river, marine and mixed river dynamics processes. This is a tidal diurnal area and a large tide amplitude is located in the tropical monsoonal humid tropics so the tidal and saltwater dynamics play an important role for this creation and development of terrain area. On the other hand, the activities of the people such as: the

waterway traffic, the sea dike, the exploitation of natural resources in the estuaries

make the study area more complex about the development of terrain, Haiphong coastline has the shape of concave curve of the western of the Gulf of Tonkin, low and

</div><span class="text_page_counter">Trang 34</span><div class="page_container" data-page="34">

fairly flat, mainly composed of sediments from five estuaries. The landscape of the estuary of Haiphong coastal area is not very large, with small slope.

2.1.2 Wind mode

‘The coastal estuary of Haiphong is dominated by two monsoon systems, the Northeast monsoon and the Southeast monsoon, In winter, this area was affected by the fighting

between two monsoon systems from the Xibiri high pressure and monsoon tide from

the East China sea. These two systems effected to take turn at the same time impact, the strong weather conditions in the season. Monsoon dominated monsoonal systems dominate the mid-winter months (from October of last year to March of next year) overwhelming the credit system. In contrasts, in the first months of winter (around November) and last winter (February ~ March), the credit system overwhelms the polar system, During the winter, the weather is usually characterized by periods of

cold (dry or wet) characteristic of the monsoon (when the Northeast monsoon appears)

alt ng with warm days characterized by the weather. In the Northeast wind season, the prevailing trend is the North, North East average wind speed is usually 3.2 - 3,7 rvs, Monthly average of 3-4 winter monsoons, lasting from 5 to 7 days, is causing by small rains, early wind speed day reached 5-6 level (equivalent to 8-13m/s), and the ‘maximum wind speed in the islands can reach 25-30 mis then gradually decrease. [8]

</div><span class="text_page_counter">Trang 35</span><div class="page_container" data-page="35">

‘Table 2.1 Frequency of wind velocity and annual directions at Hon Dau (1960 - 2011)

</div><span class="text_page_counter">Trang 36</span><div class="page_container" data-page="36">

2.1.3 Hydrographical characteristics

‘The water content of the Red River delta is influenced by the Southwest monsoon

(summer), tropical cyclone (autumn) and hurricane (autumn summer). The period of

several countries lasted from June to July, the largest flow on the Red River appeared in August and the smallest flow appeared in March,

Every year, the Hong and Thai Binh river systems provide about 120 billion mÌof

water and 114 million tons of alluvial coastal areas. This material is mainly through 9

ty, Van Ue, Thai Binh, Tra Ly, Ba Lat, Ninh

main estuaries: Bach Dang, Cam, Lach T

Co and Day rivers. According to Haiphong coastal area, there are direct impacts of Bach Dang, Cam, Lach Tray, Van Uc, and Thai Binh rivers. The flow regime in these rivers, as well as other rivers in Hong — Thai Binh river system, characterized by strong seasonal fluctuations. The analysis from multi ~ annual data series shows that annual water flow is mainly concentrated in annual rainy months (from June to September). Meanwhile, the remaining months are always small. In the rainy season,

the average discharge of the rivers flowed to the sea varies among 300 -2200 m’Vs,

while in the dry season, the average discharge is only wavered around 50 -300 m/s,

2.1.4 Oceanographical regime

‘Water level fluctuations in Haiphong coastal estuary are typical dynasties and almost ays in the month are the tidal and semi-diurnal tide only appears 2-3 days in poor water. In one tide phase, there is one high water and one ebb-tide, In one month, the moon has two periods of intense water, each period has 11-13days with 2.6-3,6m ‘average amplitude fluctuation and «wo periods of poor water each period has 3-4 days with 0,

1.0m amplitude. Tidal wave has the characteristic of standing wave with the

diurnal wave is only the secondary role with relatively small amplitude

During the year, tidal oscillations reached the maximum values during drought period when maximum solar flux in June and December and opposition was the smallest in the tidal dip when the solar flux equal “0” in March and September. During March,

</div><span class="text_page_counter">Trang 37</span><div class="page_container" data-page="37">

April, August and September, the tides are falling with the tidal of 3-4 days a month,

2.1.5 Wave regime

‘The estuary of Haiphong coastline is a shallow bay which has very complex bottom topography due to the rivers systems and fluctuating channel. The wave of deep water

‘goes to the shore due to the influence of bottom friction, the characteristics of waves

such as: propagation speed, height, cycle, and length as well as the direction of movement always change. So, the wave regime is distinct from the deep-water wave regime in both trend and high-level.

During the winter, the action of NE monsoon is strong both frequency and speed. Due to Cat Hai and Cat Ba island is significantly shielded to reduce the wind energy impact ‘on the sea. Furthermore, the wave length is short and the depth is mall so it is less

‘developed in the study area than offshore. However, during the tides, wind waves still

have conditions for development and refraction of wave propagation into coastal areas. In the season, the prevailing waves are E and NE and average wave height is 0.5 — 0.6m, The maximum wave height about 2.0 -2.5m in the coastal area east of Do Son peninsula wave height can be up to 3.0m.

In summer, the windy regime is characterized by the opposite of both winter and high altitude, The wend of wind wave is prevailing, the major influence on the hydrodynamic process of study area is SE and S$ with high frequency of occurrence. Particularly in June and July moths, the N direction of wave dominates strongly affecting the erosion of the banks of the N side of Dinh Vu peninsula and Cat Hai island as well as the channel area. The average wave height is 0.6 -0.8m, During this period, there are often storms and tropical low-pressure landings into the area causing

big wave and wind.

</div><span class="text_page_counter">Trang 38</span><div class="page_container" data-page="38">

Table 2.2 Frequency of wave heights and directions at Hơn Dau (1970 -2011) [8]

Fgh range

-tials Jos Jos ho | — lấp fast

os bác (Po 3 li32035 |2ssape30

NÓ 19 ior [ao 5» bơi foc loo [oor 0s

NNE 041 023 [0.30 013 |003 6000 000 [0.00 |L09 INE 180 |L07 138 067 |009 002 000 oor |s.o4 ENE 093 074 |092 051 |006 601 000 or bus E 942 |525 [oss 358 |029 Joos 001 oor 2S22 ESE lãi [ost 30 056 J010 002 002 oor l3 SE 513 261 j410 250 J031 J005 001 |003 |i473 SSE 043 047 |o80 095 [020 602 000 [ooo 292

is Los joes [196 230 |044 [oor 000 [oor _|o.as

</div><span class="text_page_counter">Trang 39</span><div class="page_container" data-page="39">

‘The result of statistical analysis of wave rule data for several years (1970 ~ 2011) at Hon Dau, the main wave directions affecting this area are E, SE, § and NE with the frequency of 25.2, 14.7, 6.5 and 5% respectively. According to the above anal}

ight of less than 0.5m accounted for 52% (of which about 28.2% is calm is, the

Wave), the wave height of more than 1.5m only accounted for about 15% of the total data. [8]

2.2 Simulating the development of Nam Dinh Vu new economic zone

2.2.1 Introduction about MIKE 21 model

MIKE 21 is a 2D surface flow model, the Mike 21 model is used to simulate hydraulic

proces estuarine areas, bays, coastal areas

es and environmental phenomena in lake: and waters. In order to design the structure of sea dykes in Nam Dinh Vu - Haiphong new economic zon srmine the impact of waves, currents andthe problem is to de tidal currents on river mouths in dry and rainy seasons, from which to find the compensation — erosion rules through the application of mathematical models to simulate this process. MIKE 21 is widely used in the calculation of estuarine, coastal and marine dynamics. MIKE 21 is used to calculate some modules such as tide calculations, grid netting, calculating coastal river mouth flows, calculating wave propagation from offshore to coastal areas, wave in the harbor area, sediment transport calculations, transpiration calculations, ol spill calculations, storm surges ealeulations, salinity intrusion calculations, etc... Within the scope of the research, the author uses the MIKE 21 model to calculate the simulation of the shoreline to determine the flow velocity, and the wave height in front of the building.

2.2.2 Collected documentation

2.2.2.1 The topographic

To carry out the contents of this thesis, the necessary documents have been collected and processed. These are documents that have been synthesized from research results