FLAP VALVE HDPE FOR ANTI-FLOODING PROJECT IN HO CHI MINH CITY

I. INTRODUCTION TO THE ANTI-FLOODING PROJECT IN HO CHI MINH CITY. HO CHI MINH
According to the master plan was approved by the Prime Minister about the anti-flooding project in HO CHI MINH CITY. Số1547 text at the Ho Chi Minh/QD-TTg on October 28, 2008, there are 12 drain built prevents the mouth of the river flowing out of the Saigon River, the river and the river Friends House Vam grass.
Table 1: the tribute against flooded HO CHI MINH CITY. Ho Chi Minh


Figure 1: map project has deployed 12 tribute

II. THE ROLE, THE MISSION GATES IN ATTENUATED WORKS AGAINST HO CHI MINH CITY. HO CHI MINH.
2.1 characteristics of gate valves in the works against flooded HO CHI MINH CITY. Ho Chi Minh
As well as the irrigation in the coastal region to the other, works against attenuated HO CHI MINH CITY. (CtcnuTP.HCM) must have gate valves to make the task of stopping North Korea unleash floods and to regulate the water level when necessary. But Gates in ctcnuTP.HCM has the characteristics that at least meet in the other irrigation in our country, there are large valves: scale: construction works on the wide river hundreds of yards deep and up to 15 ÷ 20 m, such as Banana, Ditches Player River River The River Channels, Highway … so can’t do the drain cavity in works such as the narrow infield which must do the drain cavity wide to goal escape fast and guaranteed traffic. Here the width of the door van more than 30 m, height can be up to 15 m. So the weight of 400 tons to valves. In developed countries, the scale of such valves have been many applications especially for the construction stopped, but for our country’s problems, especially the new fabrication, transportation and installation. Gate valves work in the big city: this is an important criterion, by definition must have works in harmony with the urban works, are regarded as architectural works on River Metro area. Gate valves work in the conditions of Sale diurnal Sea, large amplitude, flooding upstream and precipitation in the great basin. The working mode of the gate valves are complex: the duty of the Court to prevent a moderate tribute high-process ensures objective advancing, again just to create the capacity to hold rain water and dirty water discharge combination to combat pollution for some areas of the city.
2.2 tasks of gate valves in the works against flooded HO CHI MINH CITY. HCM
Tide water level pane:
-When the water level at high tide to prevent intrusion of water into the river. Depending on the terrain of the public process that decided to prevent the water level in the High Court.
-Creating capacity of rain and flood water. About the rainy season flood according to the weather forecast, it may prevent the Court into the River, including the lowest tide to create water storage capacity, to provide supplies of fresh water. Remove the flood water and rain water: When there is rain and flood, they must select at lower tide water to drain without causing attenuated the city, this was a time draining its maximum to avoid flooding due to rain, flood and mixed infections tide.
Create the top of the country to fight against pollution: by closing the valve opening control in the tribute to the North and the South drain created disparity between them to have the flow through these sections often have no flow. So need the build process during the operation of the drain against flooding. Gates served for: marine traffic for HO CHI MINH CITY. HCM is very important, so when do the drain must do the locks. In addition each drain at least a qualified valves to vessels through the back when no valves are closed.

2.3 requirements of gate valves in the works against flooded HO CHI MINH CITY. HCM
The operation of the gate valves of large aperture works against flooding must achieve high reliability, ensures against flooding. In addition, gates must have aesthetic, in harmony with the beauty of the town.
Close the valve opening time is fast enough and must be synchronized in both systems: by mode, so to prevent the water when the tide up and promptly remove the flood when the tide down to the application of these types of catches with the ability to quickly open and close to use the modern operating equipment. On the other hand the work projections the Court must correct promptly. Operating procedures should set for both systems must be carefully set details and will improve gradually in process management. Gate valves are designed, installed and
modern action but must be compatible with existing technology level of our country maintenance, repair shop van easy. This is also a practical requirement to contribute to enhance the effective management of buildings. Van door structure does not cause disadvantages for the construction of marine structures. There are types of valves requires the complex marine structure must then consider the application. The price is also reasonable valves in the total investment for the projects.

III. SELECTION CRITERIA FOR REASONABLE VALVES

3.1 the approach to the choice of structural layout and equipment of control valves.
The river sure valves waves, storms, tidal surges have many differences with gates on the clue of irrigation, hydropower. Use of gate valves on the more complex, more diverse so must study and understand and to combine the required to achieve the result, satisfying the most demanding goals. However, the difference in water level of the door on the river not too large, but there is a large aperture, so the total pressure on the door is still very big, the weight of large valves, making it difficult for the construction accuracy on request, simultaneous installation problem up great interest also works. The important task is to ensure that marine transportation according to the level of national traffic rules. Because Gates is a division of work so it’s always important, mutual influence between the categories of works.

3.2 the parameters of
Location of the building would affect the quality, the price, the target use of the work, which affect the selection of the type of gate valves. Location of the building must meet the following specific conditions:
-Convenient for: this is the most complicated tasks when building works on the River (location to folding, no ventilation, easy anchoring, moderate flow rate not be Eddy, not muscle spasms …);
-Minimize the degree of reinforced Foundation (a hard surface, do not compress the slump, reinforcing the Foundation of inexpensive, secure the do not compress or deflect the influence to operate gate valves);
-Limit the impact loads up structures (hydrostatic, marine mud, sand deposition, waves);
-Convenient Manager works (road traffic to internal works, works, information …);
-Minimize the impact the surrounding environment (water, air, noise).

3.3 the works related to the choice of gate valves
-River depth (affects the height of the door, the water pressure, operate).
-Traffic flow (operating pressure, influence cards).
-The water level and tide’s agitation level (pressure on the door, door textures …).
-Wind strength and direction of wind (impact operation, load when catches up off the ground, causing the waves).
-The temperature of water and air (expands).
-The characteristics of the background (the cause of deviation, trapped when sunk, mud sand deposition).
-Consider global climate change (water level rise made the ability to load reduction valves, air capacity, operating close to open water, crossed the top of the door).
-Riverbed morphology (affect the load of sand, mud, water pressure is distributed).

3.4 The loads acting on the van door
-Hydrostatic pressure, hydraulic pressure, the waves, the wind pressure (door size, door type, load bearing capacity).
-The load itself (open-closed power related, right top door …).

3.5 requirements for marine traffic
-Train speed (safety through works, bumps, waves acting on the door).
-The load (the depth, the level of traffic, influence the size of the compartment door).
Static Mode-no (traffic level, large, complicated itineraries).

3.6 operating elements
-Protection from floating material (safety, not jammed, doors closing the channel)
-Marine traffic safety (not yet).
-Sludge residue deposition (reduce the deposition in the process, increase power to open)
-Erosion (erosion-causing foot works, causing loss of safety).
-Maintenance and repair (easy, convenient maintenance position, easily removable).
-Longevity (life expectancy affect investment, quality of materials, maintenance).
The problems outlined above will be the basis for structural form selection door closing devices, open the valve and the other structures of the buildings.

IV. SOME TYPES OF GATE VALVES FOR CTCNUTP. HO CHI MINH
Based on the above criteria, according to the principle of operation and the type of structural form catches then some sort of appropriate valves for ctcnuTP.HCM was next in the order of priority in the following table:  
Table 2: types of gate valves suitable for works against attenuated HO CHI MINH CITY. Ho Chi Minh


Figure 2: the layout of the door on the valve works

V. CONCLUSION
The selection was kind of gate valves application in accordance with condition ctcnuTP.HCM based on the analysis of evaluation criteria are essential. Top objectives is to find scientific methods of analysis to be able to choose the model most reasonable design valves. Through the results of the research project: “research design, fabrication, installation and operation of a number of new-type valves serve against the HO CHI MINH area attenuated. “Initial results of the study to the catches of large aperture type for the river flooded the city against the pane. To have been the basis of more specific choices about the kind of large aperture valves need more intensive research from which research results are going to be the basis for the specific application for works. Successful application of large-aperture valves type for ctcnuTP.HCM project will open a new period for the application of the large valves in the process control of the Court in the coastal region, served his career against sea-level rise in our country.
REFERENCES
[1] The Ministry of AGRICULTURE and rural development, 2008-&, report unique irrigation projects against attenuated the area SAIGON.
[2] Technical manual Tabor benefits-part 2-Episode 4-door van & collapsible equipment-agricultural Publishing House, 2005.
[3] Report the results of studies of the subject “research design, fabrication, installation and operation of some type valves
served against attenuated the area of Ho Chi Minh City “-2012. 

Author: ThS. Le Dinh Hung, GS. TS. Zhang Family Example
The Marine Institute