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MINISTRY OF EDUCATION&TRAINING MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT THUYLOI UNIVERSITY PHAM VAN LAP STUDY THE FLOW VELOCITY DUE TO WAVES AT SHALLOW TOE IN THE DESIGN CALCULATION OF THE DIKE TOE BY FILL ROCKS, APPLIED TO CATHAI SEA-DIKE-HAI PHONG Specialization: Hydraulic Engineering Code No.: 9580202 SUMMARY OF DOCRORAL DESERTATION HANOI, 2019 The thesis has been completed at the Thuyloi University Supervisors: 1: Assoc Prof PhD Le Xuan Roanh 2: Prof PhD Ngo Tri Vieng Reviewer 1: Prof PhD Tran Dinh Hoa Reviewer 2: Assoc.Prof PhD Phung Dang Hieu Reviewer 3: Assoc.Prof Tran Thanh Tung The thesis will be presented at the meeting of the University Doctoral Committee in room No……………….on…14:00, day 21st, June, 2019 The thesis can be found at: - The National Library - Thuyloi University INTRODUCTION The rational of the thesis Located in the tropical-monsoon climate, Vietnam has a long coastline and is often affected by many storms There are to 10 storms occurred during the year with a high scale of wind speed and some time they occurred later or sooner of the year climate In fact, in the past years, sea dykes and revetments are affected seriously after the storm leading to a large amount of money to repair them The dike toe protecting the sea side has main forms such as high revetment toe, shallow revetment toe and deep revetment toe Based on materials, it can be classified as: stone carpet, cylinder hollow well inside inserting rocks, pile and reinforced concrete sheet, steel sheet and so on Calculating the size of stone is advised the formula (1.37) of TCVN9901: 2014 that is proposed by Izobat This formula only mentioned three factors: wave height, water depth and wavelength On the other hand, this formula is used linear wave theory for calculation In fact, rocks laided on the sea bed closed to dike toe are always pushed to slope of the embankment or moved to sea side, or along shore In fact, the phenomenon of rock sliding on the roof, up and down, friction between the rock and the revetment has caused abrasion and damage to the roof protection structure For the above reasons, the impact of abrasive rock embankment is very dangerous to the safety of the embankment, it is necessary to find the exact velocity at the foot of the embankment (dike toe) so as to determine the weight of stones accordingly The topic "Study the flow velocity due to waves at shallow toe in design of dike toe by fill rocks; applied to Cathai sea-dike-Hai Phong” has been proposed for research Research objectives The thesis will solve the following two basic objectives: - Clarifying the effect of hydrodynamic and geometric factors on the current velocity due to wave at the dike toe by using rocks; - Determining the formula to calculate the maximum flow velocity at the foot of the embankment (dike toe), then select the solution to design the structure of the foot protection of the embankment in both with or without roughness structures Subjects and scope of research - Research object: flow due to wave at seadike toe; - Scope of research: dyke toe in the North of Vietnam Research content - Overview of stabilizing the sea dike toe using filled rock; - Study the flow velocity due to wave at shallow sea dike toe by physical model; - Digital model to study flow at shallow seadike toe Approach and research methodology 5.1 Approach In order to solve the objective of the thesis, the author chooses the inheritance method which is both creative and suitable to the conditions of Vietnam 5.2 Research methods - Methods of general research; Experimental method; Digital model method; and applied research methods Scientific and practical significance - Scientific significance:The thesis has proposed a new calculation formula as a scientific contribution - Practical significance: Finding the maximum velocity at the foot of the revestment by the wave, propose a procedure to check the stone stability at the foot of the embankment CHAPTER 1: OVERVIEW OF SEA-DIKE TOE STABILITY BY FILL ROCKS 1.1 Structure of the sea dyke toe 1.1.1 General structure of sea dykes The structure of normal sea dykes has the following main components [1], [2], [3], [4]: Dyke body, dike base, protection layer of sea side slope, dike top parts: dike face and dike crest wall, protection structure for land side slope, drainage ditches 1.1.2 Overview of protection layer of sea-dike toe The toe dike is kept the protechtion layers and the upper structures from moving down due to the impact of external forces such as waves, currents, floating objects and other impacts causing instability The toe dike also has the task of forming a composite structure to protect the dike body when the erosion pit appears at the base of the embankment Materials for foot embankment and toe can be stone, hollow cilinder well, sheet, concrete pile or other material to protect the embankment According to the geometry of foot embankment can be classified into types: shallow dike toe and deep dike toe 1.1.3 The shallow toe of sea dike The standard of classifying sea dike toe according to hydraulic boundary is as follows: shallow dike toe : 1.0 < ds / (Hm0,0) < Very shallow dike toe: 0.3