Journal of Water Resources Science and Technology No.45
Create date: 07/26/18

 

WATER RESOURCES SCIENCE AND TECHNOLOGY JOURNAL
No 45 (July/2018
)

Page

Article

Author

Summary

I

SCIENCE TECHNOLOGY

 

 

2

NGHIÊN CỨU ĐÁNH GIÁ TRỮ LƯỢNG KHAI THÁC NƯỚC DƯỚI ĐẤT CÁC DẢI CỒN CÁT VEN BIỂN TỈNH HÀ TĨNH PHỤC VỤ CẤP NƯỚC SINH HOẠT CHO VÙNG KHAN HIẾM NƯỚC

 

Hoang, Nguyen Van

IGSVN - VAST

Cong, Nguyen Thanh

Cong, Vu Quoc

Vuong, Nguyen Huy

Quang, Tran Van

HCI - VAWR

 

 

 

 

 

The assessment of the groundwater quantity in coastal sand dunes to supply for the water scarcity areas in the Northern Central region is very necessary and a pilot assessment conducted for the coastal area of ​​Ha Tinh province is presented in this article. An analytical method used to determine the exploitable quantity of grid cell basis has been programmed for numerical calculation. The results show that groundwater in the sand dunes of Ha Tinh province in an area of ​​about 95 km2 can provide about 10,390 m3/day during 27 years of exploitation under the most unfavorable condition without rainwater. The average exploitation volume from the coastal sand dunes is 109.69m3/day/km2, equal to approximately one-fourth of the rainwater of 395.78m3/day (infiltration rate is 10%). The exploitation of groundwater from the sand dunes has a role that promotes the rate of rainwater infiltrating into groundwater, increasing the volume of groundwater quantity in the area compared to those areas without groundwater extraction. The results of this assessment are of great practical significance in the development of master plans of groundwater exploitation in the water scarcity areas in the Northern Central region and this is a basis to assess salinity intrusion and spreading of pollutants in the groundwater of the coastal sand dunes into the groundwater exploitation systems as well as predict and propose measures to prevent salinity intrusion and pollution.

Keywords:Groundwater extraction, large well, grid, permissible drawdown.

12

BÀN VỀ NGUYÊN NHÂN HƯ HỎNG KHỚP NỐI POLIME QUA MỘT SỐ SỰ CỐ CÔNG TRÌNH THỦY LỢI GẦN ĐÂY VÀ GIẢI PHÁP KHẮC PHỤC

Dung, Nguyen Quoc

HCI - VAWR

 

This paper presents the analysis of incidences recently occurred in hydraulic structures because of improper installation of the Polymer waterproofs at the joints. Methods and recommendations for repair were also discussed in the paper.

Keywords:polimer waterproof; joint; fault.

20

TÍNH TOÁN MÓNG CỌC XIÊN CHÉO LỚN CHO ĐẬP TRỤ ĐỠ

Thai, Tran Van

Truong, Nguyen Dinh

HCI - VAWR

 

 

 

Pillar supported dams have shown both technical and economic efficiency. The characteristics of the pillar dams are both vertical and horizontal force bearing; the horizontal forces acting on hydraulic structures are quite large, depending on the difference of the water head of before and after the structures. Meanwhile, the vertical bearing capacity of the foundation is much greater than the horizontal bearing capacity of the structures. This paper compares the bearing capacity of the foundation of different pipe arrangments (entire vertical piles, entire inclining pipes, and large two-way inclining pipes) with the same vertical load (N), horizontal load (H). The result shows the large two-way inclining piles foundation is optimal for pillar supported dams. The paper also proposes a set of equations for pile arrangement in the pillar supported dam. Finally, the paper synthesizes results of large two-way inclining piles foundation for some projects that have been constructed or being built in Vietnam.

Keyword:the large two-way inclining pile; pillar supported dam; pile foundation

31

BƯỚC ĐẦU PHÂN TÍCH HIỆN TƯỢNG NỨT ĐÊ KHI KẾT HỢP GIAO THÔNG VÀ HƯỚNG XỬ LÝ

An, Phung Vinh

HCI - VAWR

 

The article analyzes the causes of subsidence, surface cracking of traffic-combined dykes in the Red River Delta. It can be concluded that they are concurrent influences of disadvantage factors. The causes are due to the width of the curb is small or without a curb, the content of clay and dust of the embankment is high, the weak ground was not thoroughly treated, the load exceeds the allowed limit, the compaction of the foundation was conforming to Vietnam Standard TCVN 4054: 2005. These analyses form bases for treatment methods.

Keyword:dyke surfaces; settlement; cracking; soft soil; traffic loads.

38

NGHIÊN CỨU THIẾT KẾ ỐNG LỌC NƯỚC ĐẶT TRÊN TRẠM BƠM HUYỀN ĐỂ CẤP NƯỚC CHO NUÔI TRỒNG THỦY SẢN

Dung, Nguyen Quoc

Tuan, Phan Dinh

Duc, Le Anh

Thanh, Nguyen Quang

HCI - VAWR

 

 

 

 

A filter model placed on a moveable floating deck was addressed in the paper entitled 'Moveable floating deck based filter solution supplying water for aquaculture production' on Journal of Water Resources, issue 1/2018. This paper presents experimental results on the determination of the size of the aggregates and number of the filter layers in order to ensure the quality of the output water for aquaculture farming. The experimental results are also a basis for formulating filter modules that are able to be combined supplying for specific requirements of discharge.

Keywords:water supply for aquaculture, water filter, moveable floating deck, clean salt water resources

45

TỔNG QUAN VỀ QUAN TRẮC VÀ CẢNH BÁO SỚM LŨ QUÉT BÙN ĐÁ

Thao, Vu Ba

Minh, Pham Van

HCI - VAWR

Tuan, Le Quang

Kien, Nguyen Trung

Vietnam Disaster Management Authority

 

 

 

 

Flash floods and landslides are major types of natural disasters that usually causes loss of life and damages to property in mountainous provinces in the North, Central regions, and Central Highlands. However, risk maps of flash flood and landslide have not shown specific locations and time of occurrence of the disasters. Some pilot monitoring and warning models based on rainfall and river water level information are suitable only for flash floods in river basins. While the flash floods associated with debris flow occurring in the upstream of catchments in mountainous areas, a popular hazard that usually causes serious damages, have not been studied and applied such monitoring and early warning systems. This article reviews a number of issues related to flash flood monitoring and warning in Vietnam and the world; this is a basis for analyzing options and proposing a pilot system for monitoring and warning flash floods associated with debris flow in mountainous regions.

Keywords: Flash flood, debris flow, landslide, monitoring and early warning.

57

ĐÁNH GIÁ HIỆU QUẢ CỦA ĐẬP NGẦM LÀM CHẬM DÒNG CHẢY TRONG TẦNG CUỘI SỎI VÙNG NINH THUẬN, BÌNH THUẬN

Giang, Phan Truong

Trung, To Quang

HCI - VAWR

 

 

 

 

A subsurface dam is a structure that is arranged across a groundwater channel to store shallow groundwater or slow down the seepage in the aquifer (sand, gravel, etc…). Subsurface dam technologies have been widely applied and documented in the literature, especially in dry riverbeds around the world. However, there are a few assessments of the efficiency of the available technologies, particularly the efficiency of the subsurface dam type that is partly cut-off the interflows in gravel layers. This paper presents the solutions of designing and implementing as well as monitoring results of a full-scale experiment of a semi-cross-section arrangement subsurface dam at a freshwater treatment plant in My Thanh commune, Ham Thuan Nam district, Binh Thuan province (with a design capacity of 80 m3/day in the dry season), a region where experiences severe droughts in the last 3 months of the dry season. It is found that when the subsurface dam was constructed, the water treatment plant supplied sufficient water as designed and the groundwater storage exceeded the actual yield about 6000m3. This is a good reference for applying the subsurface dam in those places that have similar geological conditions.

Keywords:subsurface dam; semi-cross-section arrangement; water scarcity regions

65

NGHIÊN CỨU THIẾT LẬP CÔNG THỨC TÍNH TOÁN ỨNG SUẤT ĐÁY MÓNG KHỐI NÊM CHO ĐÊ BIỂN NAM BỘ

Quynh, Do The

HCI - VAWR

 

 

 

Awedge base foundation comprises the wedge blocks made from soft soil, cement and additive. The blocks are arranged side by side and filled with sand in the void between them. The foundation top is covered with a sheet of tensile geotextile. This foundation was proposed since 2014 and onging studying its application for sea dykes in Mekong river delta. The establishment of the new formula to calculate the wedge base foundation bottom stress is extremely significant for evaluating the ground stability; however, it has not been established so far. This article introduces the content, research method and the result gained in the establishment of the above-mentioned formula to apply it to Mekong river delta sea dykes.

Keywords:Wedge base foundation, wedge base foundation bottom stress calculation formula.

73

NGHIÊN CỨU XÁC ĐỊNH GÓC MA SÁT TIẾP XÚC MÓNG ĐẬP XÀ LAN TRÊN NỀN ĐẤT YẾU CHỊU TẢI TRỌNG PHỨC HỢP ĐỨNG, NGANG VÀ MÔ MEN

 

Ha, Nguyen Hai

HCI - VAWR

 

 

 

A movable dam based on an extended width principle helps to reduce the stress of the foundation so that it can be directly constructed on a soft soil foundation without treatment requirement. Vertical loads acting on the foundation of the movable dam are low but horizontal loads and moments are larger because of the large difference between the water levels in up- and down-stream of the dam. Thus, the stability of the movable dam constructed on the soft soil requires detailed studies. This paper presents a study on the soil-concrete friction angle of a foundation on the soft soil as a basis to clarify the interacting mechanism and elements addressed in Ngo Tran (1996) in order to prove the suitable application on clay. Determining the interface friction angle is very essential to construct the dimensionless failure surface of the movable dam. The authors have performed a sliding experiment for a pressed concrete slab of 0.2 x 0.3 x 0.4 m; each experiment is performed with three vertical loading scales and slid until instability. The sliding experiment results to define the soil-concrete friction angle are important inputs for studying on the failure surface of the movable dam.

Keywords:Movable dam, combined loading, failure envelope

80

THIẾT LẬP MÔ HÌNH THÍ NGHIỆM NGHIÊN CỨU HIỆN TƯỢNG XÓI NGẦM DƯỚI ĐÁY CỐNG QUA ĐÊ TRÊN NỀN CÁT CÓ XÉT ĐẾN ẢNH HƯỞNG CỦA CỌC BÊ TÔNG CỐT THÉP

Trong, Dinh Xuan

HCI - VAWR

 

 

 

There were many incidents of under-dike culverts on sand foundation due to internal erosion issues recently; and most of the incidents occurred at those culverts with the foundation supported by reinforced concrete piles. With the aim to analyze seepage in the foundation under the culverts in consideration of stress state in cases with or without reinforced concrete piles, in this study, a mathematical relationship among factors of the hydraulic dynamics, structures, and soil is established based on the dimensional analysis method. On this basis, a physical experiment model is designed to perform a series of tests with different conditions. The experimental results will help to obtain the necessary data for design and safety warnings.

Keywords:Under-dike culvert, expermental model, internal erosion, sand foundation, reinforced concrete piles, stress state

90

NGHIÊN CỨU ỔN ĐỊNH ĐÊ TRỤ RỖNG TRÊN NỀN ĐẤT YẾU CHỊU TẢI TRỌNG PHỨC TẠP ĐỨNG, NGANG VÀ MÔ MEN

Thai, Tran Van

Ha, Nguyen Hai

HCI - VAWR

 

 

 

Hollow cylinder breakwater for dissipating wave energy and protecting the shoreline was first researched, applied and successfully built (180 m) in Vietnam in April 2017. This type of breakwater has many advantages such as the ability to dissipate the waves, reduce pressure acting on the structure so enhancing the stability and service life compared to vertical seawalls. The hollow cylinder breakwaters are manufacture in the factory and easily assembled on sites that help to ensure construction quality and reduce implementation time. This paper presents a method for calculating the stability of the hollow cylinder breakwater using the limit load boundary line in case the structure bears vertical, horizontal loads and moment by either increasing or decreaseing the height of rockfill inside the breakwater. When the height of rockfill increases, the vertical load acting on the ground increases leading to increases in horizontal load and moment bearing capacity for ensuring the stability of the hollow cylinder breakwater. A finite element method is used to analyze the settlement of the pilot 180 m breakwater constructed in Ca Mau. It is found that the monitoring data shows a good agreement with the calculated settlement using the finite element method given the suitable selection of model parameters.

Keywords:Hollow cylinder breakwater, wave dissipation, stability, soft soil

97

ẢNH HƯỞNG CỦA TRO TRẤU ĐẾN CƯỜNG ĐỘ, TÍNH CHỐNG THẤMCỦA BÊ TÔNG THỦY CÔNG

Trung, Nguyen Tien

Son, Nguyen Van

Tam, Vu Khac

HCI - VAWR

 

 

This paper presents a method of rice husk ash (RHA) manufacture in the form of pilot and study on the influence of RHA to strength and waterproofing capability of hydraulic concrete structures. Results show that RHA was obtained by burning rice husk at the temperature of 600 - 800oC in 24 hours. The combustion of rice husk was designated to produce ash with the unburnt carbon content of 3,6%,  SiO2 content of 90,75%, active pozzolanic index of 290 mg CaO per 1g RHA and medium particle size of 17 μm. The compressive strength of concrete using 10% of RHA is remarkably higher than that of the reference concrete without using RHA at the ages of 28 and 90 days. It provides the possibility to increase the waterproof capability and decrease the penetration of chloride ion into the concrete. The samples and laboratory experiments were followed chemical – mechanical analysis methods and standards such as XRD, DTA, SEM, TCVN, and ASTM.

Keywords: Rice husk ash; waterproof capability; hydraulic concrete structures; pozzolan; concrete strength; chloride ion penetration

102

NGHIÊN CỨU ỨNG DỤNG CÔNG NGHỆ XÂY DỰNG ĐƯỜNG GIAO THÔNG NÔNG THÔN BẰNG ĐẤT TẠI CHỖ GIA CỐ CHẤT KẾT DÍNH: XI MĂNG, ROADCEM, TRO BAY, TRO XỈ

Dung, Nguyen Quoc

Quan, Ngo Anh

Thao, Vu Ba

HCI - VAWR

 

 

 

 

Using the soil material at the site mixed with adhesives to build roads is an effective solution to reduce construction costs and environmental damage. This paper introduces the process of research and application of rural road construction technology with ON-SITE SOIL mixed with ADHESIVES including: RoadCem (RC), fly ash, ash of Aluminum factory and natural puzolan. (1) RoadCem has the effect of increasing the hydrolysis capacity of the cement when applied to the soil particles, improving the strength of RC-soil-cement, especially the bending strength; (2) fly ash, ash and natural puzolan can replace some cement, ensuring the requirement for rural roads and reducing the cost of construction. The process of receiving and transferring technology, land consolidation principles, some experimental road works, economic efficiency and research orientation will be presented in this article.

Key words: rural roads, roadcem, natural puzolan, fly ash, ash.

114

TẢI TRỌNG SÓNG TÁC ĐỘNG LÊN CẤU KIỆN TIÊU SÓNG TRỤ RỖNG TẠI ĐỈNH ĐÊ BIỂN THEO LÝ THUYẾT VÀ THỰC NGHIỆM

Thai, Tran Van

Ha, Nguyen Hai

Tam, Nguyen Thanh

HCI - VAWR

 

 

 

Along the coast of Vietnam, there are many revetments of inclining slope type combined with top vertical seawall to reduce wave overtopping flow and the height of the revetments that lead to the decrease in investment. The structure of the top vertical seawall causes large reflected waves, creating large forces to the seawall and inclining slope. Based on these facts, the Research Team on "river bank and coast protection works" of Hydraulic Construction Institute proposed structures a wave dissipation structure of hollow cylinder type on the top of the sea dike which aims to dissipate the wave; reduce overtopping, embankment, and pressure on the slope that enhance the stability of the revetments. The hollow cylinder wave dissipation structure is arranged on the top of the sea-dike with the hollows on the seaside surface and made of high strength reinforced concrete. The structures are manufactured in the factory and assembled onsite, ensuring quality and shorter time of implementation. Experimental results show that the wave load acting on the wave dissipation structure of hollow cylinder type is similar to the analytical solution of Tanimoto in the case of the unbreaking wave. In respect of the breaking wave, the wave load computation cannot be applied by Tanimoto's solution.  In the same condition of the breaking wave at the gauges, the load acting on the wave dissipation structure is about 14 % of that acting on the vertical seawall.

Keywords:hollow cylinder wave dissipation structure; wave dissipation; wave load; physical model

122

GIẢI PHÁP CẤP NƯỚC CHO VÙNG NUÔI TRỒNG THỦY SẢN TẬP TRUNG TỈNH KIÊN GIANG

 

Dung, Nguyen Quoc

Tuan, Phan Dinh

Truong, Nguyen Dinh

Duc, Le Anh

HCI - VAWR

 

 

 

 

Aquaculture production areas in Kien Giang province are planned to be largest intensive aquaculture farm in Vietnam. According to the plan, there will be an aquacultural park of 3000 hectares with the expected productivity of 35-40 ton/ha. In order to achieve those goals, many solutions must be applied simultaneously, in which, solution for water supply is the most challenging issue. This paper presents preliminary results in establishing a water supply scheme of the project as requested by the Government. The orientations on both fresh and saline water supply and the associated structural solutions are also addressed in this paper, especially the implementation of a large-scale off-shore pumping station system.

Keywords:Aquaculture, Kien Giang province, saline water pumping station

 

 

 

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