Probabilistic safety assessment of sea dikes in Giao Thuy-Nam Dinh Probabilistic safety assessment of sea dikes in Giao Thuy-Nam Dinh Acknowledgments First of all I would like to send our sincere thanks to: Assoc.Mai Van Cong and Prof. Radu Sarghiuta - my supervisor from ULG and TLU- for their concern, guidance, enthusiasm, valuable advice and assistance with so much warmth and care. My high appreciation goes to all the teachers who have taught and armed me with such a valuable knowledge to my future career in my country, my colleagues, friends and my classmates for their support, assistance and for making my stay here filled with joys and memories. Pham Tien Hung ULG-TLU-2016 REASSURANCES: REASSURANCES Dear: The management board of Thuy Loi Uni ity: ‘The management board of Liege University: My name: PHAM TIEN HUNG Major: Sustainable Hydraulic structure Student Number: 14§ULG07 Thereby declare that i am the person who conducted this master thesis under the ‘guidance of Assoc.Prof Mai Van Cong and Prof.Radu Sarghiuta with the research topie “Probabilistic safety assessment of sea dikes in Giao Thuy-Nam Dinh” This is a new res ch topic which does not overlap with any dissertation before, so there is no copy of any public dissertation.
The contents of the thesis are presented in accordance with regulations, the data resources and materials used in research are quoted sources. If there is any problem with the contents of this thesis, I would like to take full responsibility as prescribed, Hanoi, August 15, 2016 Applicant PHAM TIEN HUNG ‘TABLE OF CONTENT TABLE OF CONTENT Contents Acknowledgments 1 REASSURANCES. 2 ‘TABLE OF CONTENT 3 (CHAPTERI: INTRODUCTION 1 uu Background and justification 1 12, Aimefsudy, 1 13. Saudy approach 2 14, Outline of sud.
2 (CHAPTER 2: GENERAL OVERVIEW OF STUDY AREA, 3 24 (Current status of sea dike system in Giao Thuy - Nam Dinh 3 22. Some features of Giao Thy’ sea dikes 3 23. General assessment ofcurrent situation of sea dike system in Giao Thuy ieriet. Some natural boundary condition in Giao Thuy- Nam Dinh lô 4) DelaltopogHaphy in Đ) Soil characteristics and Geological features w ©) Sediment transport conditions, " Climate and Meteoroogy " ©) Oceanography: ø Đo Winds a Waves "“ (CHAPTER 3: Probability risk an reliability assessment.
General introduction Is 32. General background of probability theory 6 4) Riskanalysis, 6 b) Reliability analysis „ 33. Probabilistic reliability analysis of sa dikes system in Giao Thuy-Nam Dinh. Mechanisms ofinstability of armour layers of revetment n ©) Toe foot instabilities 31 Piping 2 ©) Sliding o dike stope.
‘CHAPTER 4: Applying probabilistic reliability analysis to safety assessment in Giao Thuy ~ Nam) Dink. Instability of armour revetment: 40 ‘TABLE OF CONTENT 43. Toe foot instabilities 4 44 Piping “ 45, Sliding of dike slope 3 46. Probability dike system failure 5s (CHAPTER 5: Conclusions and recommendation 5a ‘Conclusions on safety ofthe sea dikes in Giao Thuy ø 5.
Recommendations ái References 6 AppendixI: The parameters of Giao Thuy sea dike design according to technical standards in sea dike design 2012), “ 4) Grade of stueture “ b) Design water level 6 © Deep-vater wave. 6s 4) Design wave neat the te ofthe dikes a ©) Require free board by wave overtopping. » 1) Design revetment thickness (technical standards in sea dike design 2012) n Appendix 2: Geotechnical document use in calculating siding ofdike slope T4 “Appendix 3: Determining failure probability of sea dike system in Giao Thuy by using OpenTA, software 76 Appendix4: Fragility curve a LIST OF FIGURES Figure 2.1: Map of sea dike system in Giao Thuy- Nam Dinh 3 Figure 2.2: Erosion in dike slope of Giao Thuy sea dike 4 Figure 2.3: The flood eaused serious damage on field region in Giao Thuy-Nam Dinh 5 Figure 2.4:Damage of dike section dục to Typhoon 1 (2016) 6 Figure 2. 5: Dike section improved by funding of PAM 7 Figure 2.6: Sketch of double sea dike system at Giao Thuy disict(ceg- mai 2001), 7 igure 2.7: Representative cross section of sea dike in Giao Thuy-Nam Dịnh (ceg_mai_2008) 8 Figure 2.
8: Main seasonal wind directions in northern Vietnam GB Figure 3. Frame work of risk analysis (ce CUR HH, 1990).2:Defintion ofa failure boundary Z0, „ Figure 3.3 Definition of probability of failure and reliability index 2 igure 3.1: Fault tee of Giao Thuy sea dike E Figure 3.5: Damage of sea dike caused by wave overtopping 26 Figure 3,6 Pore pressure in the subsoil daring wave run-down (Piatczyk e al, 1998).7: Schematization of scour mechanism at Nandlnh revetment.8: Mechanism ofpiping at sea dike 2 Figure 4, 1: The normal distribution of MHWL based on BESTEIT software ” Figure 4.2: Contribution of parameter to overtopping lalure move in eursent dike 3” Figure 4 3: Contribution ofparameter to overtopping failure mode in dike according to design standard 2012 40 Figure 4.4: Contribution ofparameter to instability armour of revetment in currently để Figure 4 5: Contribution ofparameter to instability armour of revetment according to design standard 2012 44 Figure 4 6; Contribution ofparameter to foe foot istasiities 4s Figure 4, 7:Contribution of parameter to piping failure condition| sỉ Figure 4.8 Conibuion of parameter to piping failure condition 2.9: Safety factor ofslope stability calculation in Outer slope SEmin=l 50 34 Figure 4. 10: Safty factor of slope stability calculation in Inner slope SFmin=1. 11: Fault ioe analysis of Gino Thuy sa dike system for present situation, 56 Figure 4, 12: Fault wee analysis ofGiáo Thuy sea dike ccording to Dike Design Standard (2012) sr Figure 413.
Fragly curve a a function of the design wave height(H)-Appendix 4, page 93. 59 Figure AI, 1: The Mean High Water Line in Giao Thuy - Nam Dinh 6 Figure AI, 2: Plan of regions used to determine the parameters of deep-water wave 66 Figure A4. I: Fragility curve asa funetion ofthe design wave height (Hs) 8s LIST OFTABLES “Table 2.1: Sediment load composition onthe shoreline of Giao Thuy " ‘Table 4.1: Stochastic variable for mochanism of wave overtopping 38 ‘Table 4.2: Failure probability ofthe dike due to overtopping 38 Table 4.3: Contribution of parameter to overtopping [are mode.4: Stochastic varie for instability armour ofrevetment 2 “Table 4.5: Failure probability and contribution of parameters to instability armour revetment in curtealy by using VAP. đã Table 4,6: Failure probability and contibution of parameters to instability armour rẻte0nenfin.
dike acconding to dike design standard 2012 by using VAP. :Stochasie variable for mode oft Foot instabilities. a7 Table 1 8: Failure probability and contibution of parameters to (oe foot instabilities by using VAP 7 ‘Table 4.9: Stochasue variable for mode of piping 0 ‘Table 4, 101 Falue probability and contribution of parameters to piping failure condition | by using VAP.11: Falue probability and contribution of parameters to piping ailare condition 2 by tảng VAP. 2 ‘Table 4, 12: Falure probability of siding of dike slope in Outer slope and Inner slope by using var.
13: Overall probability of failure at Giao Thuy sea dikes 56 ‘Table AI, [: Safety standard and grade of sea dike “ ‘Table AI, 2: The parameters of deep-water wave in region Hai Phong Ninh Bình a Table AI, 3 Theresults of wave tansportation by using SWANID software ) Table AL 4: Average overtopping rates are allowable according to Technical standards in sea dike design (2012) T0 Table AI, Š The requted crest free board accorling to g=10 (im), + Table AL. 6 The erst level of Giao Thuy sea dike cording to safety design standard n ‘Table A2. [Test result of physial and mechanical properties of soil layer 1 1 ‘Table A2 2: Test result ofphysical and mechanical properties of sil layer 2 ”% 5. Test result of physical and mechanlcal properties of soil layer 3 T5 -Tex result of physical and mechanical propertics of soi layer 4 75 (CHAPTER: INTRODUCTION CHAPTER: INTRODUCTION 1.
Background and justific: Vietnam is a typhoon prone country lo ted in the tropical monsoon area of the South East Asia. The majority of Viet Nam population lived in the low lying river flood plains, deltas and coastal margins which involves mainly in agricultural and fishery sectors. In recent years, evolution of natural disasters and weather in Viet Nam was. ‘complications, typhoons from the South China Sea bring torrential rainfall and high winds to the coast and further inland.
On average four to six typhoons attack the coast annually resulting in heavy damage, loss of life, and destruction of infrastructure facilities and services. The reason why the water disasters are so serious is that most of the population lives in areas susceptible to flooding. Thus the formation and development of defensive system are alway’ attached to life and production of people from generation through the generation. ‘Nam Dinh province in general, Giao Thuy district im particular constitutes part of VictNam’s witha long line of dikes and sea defenses.
Most of the sea dikes are built ‘over the centuries mostly due to local initiatives and have generally an inadequate {design and are poorly constructed. Due to the bad state of the dikes significant part of the yearly funds has to be allocated to repairs and maintenance. Although, before flood season in every year, several researches on the safety assessment of the coastal defenses system have already been conducted but these researches ’s weakness wete done based only on what already happened of the sea defenses system in the previous years and the experiences on management of the monitors. As a result, the risk of the damages is still going on at the high rate and frequently and establishing method for asses sing safety of sea dikes based on reliability analysis theory is necessary.
Aim of study Probability safety assessment of sea dikes in Giao Thuy-Nam Dinh. The aim ofthis CHAPTERI: INTRODUCTION, study can be outlined as follows: = Establishing method for assessing safety of sea dikes system based on reliability analysis theory. = Setting up cases of risk in using reliabili analysis of this sea dikes system, - Suggesting the criteria to e imate safety according to reliability analysis = Finding fragility curve of Giao Thuy sea dikes ~ Applying results achieved to assess safety ofa case study in Giao Thuy district.3, Study approach ~ Applying reliability analysis thesis ~ Studying the documents involved designing and optimizing sea dikes based ‘on reliability analysis theory at home and abroad. ~ Inheriting early researches relating to sea dikes, 1.
Outline of study ~ The general information of the study is given in chapter | = In chapter 2, description of overview of Giao Thuy-Nam Dinh and some natural boundary condition, - The probability risk and reliabi assessment and applying probability reliability analysis to safety assessment in Gino Thuy-Nam Dinh are presented in chapter 3 and chapter 4, There will be investigated all kind of failure modes which may occur and estimated which factors have the greatest impact to the failure of sea dike ~ Finally, the conclusion and recommendations will be treated in chapter 5. (CHAPTER 2: GENERAL OVERVIEW OF STUDY AREA CHAPTER 2: GENERAL OVERVIEW OF STUDY AREA 2. Current status of sea dike system in Giao Thuy ~ Nam Dinh. Long ago, sea dike system has played vital role in the natural disaster consequences prevention and mitigation.
Furthermore, in the present recessionary conditions, defense system also has essential role as protection for residential and urban areas to censure the sus tainable economic development. Giao Thuy is a coastal district of Nam Dinh province, 35 km South away from Nam Dinh city. It is bounded on the Northwest by Xuan Truong district and Southwest by Hai Hau district and also borders Thai Binh on the North and Northeast. (Giao Thuy district has natural area of 230.22 square kilometers and population of 256,864 people (counted in 2010), surrounded by 27 km of sea dikes from So estuary to Hong estuary.