Structural solution for the dike with slope type protected by soil stabilized block covered by polypropylene bag

In Vietnam, amour stone, concrete, reinforced concrete and polypropylene bag have been widely used in the construction of sea shore protection. The main reason causes erosion of the coastal area is the wave and current. Thus, for sea shore protection, coastal reinforced materials are resistant to erosion by seawater, wave load and current load.

HAPPY NEW YEAR 2018 STRUCTURAL SOLUTION FOR THE DIKE WITH SLOPE TYPE PROTECTED BY SOIL STABILIZED BLOCK COVERED BY POLYPROPYLENE BAG TRAN LONG GIANG1, NGUYEN THI DIEM CHI2 of Research and Development, Vietnam Maritime University 2.Faculty of Hydraulic Engineering, Vietnam Maritime University 1.Institute Abstract In Vietnam, amour stone, concrete, reinforced concrete and polypropylene bag have been widely used in the construction of sea shore protection The main reason causes erosion of the coastal area is the wave and current Thus, for sea shore protection, coastal reinforced materials are resistant to erosion by seawater, wave load and current load The use of natural materials such as stone, heated materials such as cement and lime in construction of dike often leads to high construction costs and environmental impact Facing this situation, the research of structural solution for the dike with slope type protected by soil stabilized block covered by polypropylene bag is a completely new direction, bringing both high economic efficiency and helping environmental protection Keywords: Shore protection construction work, soil stabilizer, wave load, current load Tóm tắt Ở Việt Nam thường sử dụng vật liệu gia cố bờ đá đổ, bê tông, bê tông cốt thép bao địa kỹ thuật Đối với gia cố bờ biển nguyên nhân gây xói lở mạnh với bờ biển sóng, sau dòng chảy Các vật liệu gia cố bờ phải chịu xâm thực ăn mòn nước biển, tải trọng sóng dòng chảy Việc sử dụng loại vật liệu tự nhiên đá, vật liệu nung xi măng, vôi xây dựng cơng trình kè bờ thường làm cho chi phí xây dựng cao ảnh hưởng đến mơi trường Trước tình hình đó, việc nghiên cứu xây dựng kè chống xói lở bảo vệ bờ khối đất hóa cứng bọc vải địa kỹ thuật hướng hoàn toàn mới, vừa mang lại hiệu kinh tế cao với chi phí xây dựng thấp, vừa giải vấn đề mơi trường Từ khóa: Kè bảo vệ bờ, đất hóa cứng, tải trọng sóng, dòng chảy Introduction Vietnam has a coastline of more than 3260 km which located in the monsoon zone, thus this coastline often has influenced of typhoons In recent years, strong typhoon combined with high tide have caused serious damage for some beautiful sea shore areas In order to exploit effectively shorelines, the choice of the proper protected structure type plays a very important role Currently, the design and construction of dikes in Vietnam are mainly traditional structures that using much materials such as bamboo, stone, concrete, reinforced concrete, steel, However, these structures are often unstable when constructed in weak soil areas and often requires local repairing Beside that the rearrangement of concrete blocks require the complex construction equipment and handling techniques The most common damage to traditional types is foot erosion, the roof sagging, and deformation of whole structures Some of the embankments were badly damaged during the recent storms such as Cat Ba - Cat Hai embankments, Vu Long - Vu Binh and Vu Dong embankments in Thai Binh Province, Ha Long embankment - in Quang Ninh Province that have caused great damage to property, even unsafety for people Therefore, in this paper, the authors have studied and proposed solutions to build embankments to prevent erosion, protect the shoreline by the new type of dike constructed from soil stabilized block covered by polypropylene bag The proposed solution for dike constructed by stabilized soil covered with geotextile bag The use of local materials combined with chemical additives to harden the soil has been implemented in transportation and irrigation works in some developed countries such as USA, UK, Japan, Australia, and in Vietnam the implementation of this application for new construction, repairing of roads are applied quite a lot However, this technology has not yet been applied to irrigation works due to the concerns about decomposing materials in the sea water environment for long-term work, and it is difficult to compact the soil without specialized compressing equipment In this paper, the authors present the solution using the soil stabilized block covered by polypropylene bags that will be compressed when stacking together In addition, new technologies for soil hardening have been developed so that they can be used for many types of soil such as lateritic, clay, sandy soils Beside that the local chemical additive will help reduce the cost of building 26 Journal of Marine Science and Technology No 53 - January 2018 HAPPY NEW YEAR 2018 in comparison with using the imported additives such as DZ33 (United States), RRP (Germany), Consolid (Switzerland), [2], [3], the research and construction of embankments to prevent erosion and protect the shoreline by the soil stabilized block covered by polypropylene bag is highly feasible Structural solutions for dike with stabilized soil cover by Polypropylene bag are based on the following principle: local soil is mixed with chemical additive and enclosed by Polypropylene bag (Figure 1), the blocks are calculated and arranged so as to ensure local stability, general stability Soil bags can be stacked with common earth moving equipment such as excavators (Figure and Figure 3) Figure Construction of soil mixed with additives into Polypropylene bag Figure Using excavator to stack the stabilized soil bag to build dike Figure Coastal embankments were constructed using Polypropylene bag filled with stabilized soil The steps for calculating an embankment structure using stabilized soil and Polypropylene bag are proposed as follows: - Design of new material ingredient; - Selection of geotextile type; - Determining the size of the construction; - Determining the load on the construction; - Calculating the erosion resistance of the construction; - Calculation of general stability of the dike; - Calculation of local stability of soil stabilized block Application of new design for the dike in Tien Giang river bank In this paper, authors have presented the design of construction of dike in Tien Giang province using new structures in 2014 Figure shows the erosion of the embankment due to the current and wave caused by ships Construction progress of dike with new type illustrated in Figure and Figure The bag size selection is depend on the hydraulic condition at the position of construction, working method and stability of block For the small river in Tien Giang Province, the flow speed is small, construction method is manual, therefore after testing some the bag sizes, the bag with size 100x40x20cm have been selected for construction dike Calculation of work stability according to the deep sliding scheme and is determined according to the following formula [1]: Journal of Marine Science and Technology No 53 - January 2018 27 HAPPY NEW YEAR 2018 𝑘𝑛 ≤ 𝑚.𝑚𝑑 𝑅 (1) 𝑛𝑐 𝑁𝑝 Where: nc : coefficient of load combination; nc = 1,0 - for basic combinations; nc = 0,95 - for load combination during construction period; m - coefficient of working condition, obtained by 1,15; md - Additional factor working condition; kn - Safety coefficients according to the importance of the structure; kn = 1,1 for constrtuction level IV; Np and R - Corresponding slip force and limit resistance force Figure Erosion of river embankments in Tien Giang Province before construction of dike Figure Layout of stabilized soil bags Figure Construction of dike using soil stabilized covered by Polypropylene bag in Tien Giang Province Figure Schema of dike stabilization calculation Stability calculation of dike is carried out using GeoStudio 2007 software The order of input parameters of the model are geometric dimensions, mechanical properties of soil layers, rock layers, underground water level, sliding center, [6] Polypropylene bags are filled with stabilized soil simulated in the model with the following declaration parameters, [4], [5]: specific gravity = 18kN/m3, internal friction angle = 900, cohesive c = 1000kPa The result of calculating the slope stability factor of the dike with the GeoStudio 2007 as follows Kmin = 1,169 > kn=1,1 (Figure 7) Thus, the dike structure designed as above ensures the stability condition Figure shows the condition of dike afer years in services To evaluate the cost of new dike structure with other used dike structures in Tien Giang Province, author make comparison of cost between meter of new dike structure, 10,3 million VND (report from Cai Be - Tien Giang project), with cost of amour and concrete type, from 10 million to 15 million VND for meter, so the new dike structure can reduce the cost of dike construction 28 Journal of Marine Science and Technology No 53 - January 2018 HAPPY NEW YEAR 2018 Figure New structure of dike after years operating Conclusions The paper presents the new technical solution using stabilized soil combined with Polypropylene bag to create dike for protection of river and coast embankments This is a great solution both in theory and practice by the application of new material technologies combined with materials in place to reduce the cost of construction work, while contributing to limitation of exploitation of natural resources such as stone and sand for construction of work, contributing to environmental protection The research results of this paper can be used as a basis for the development of further studies aimed at ensuring stability, safety and reducing construction costs for rehabilitation and upgrading of dykes for river bank protection, coastal embankment protection across the country REFERENCES [1] F Dentale, G Donnarumma, and E Carratelli, “Simulation of flow within armour blocks in a breakwater,” Journal of Coastal Research, vol 30(3), pp 528-536, 2014 doi:10.2112/JCOASTRES-D-13-00035.1 [2] J Headland, S Alfageme, E Smith, and P Kotulak, “Coastal structure design for shore protection & sand retention: Practical aspects,” Proceedings of 6th International Symposium on Coastal Engineering and Science of Coastal Sediment Processes, 2007 [3] A McMillan, G Guthrie, P Patterson, T Oakes, K Taylor, G Watson and M Chandler, “Bag to the future - Meeting the challenges of coastal erosion and affordability”, Paper presented at the Coasts, Marine Structures and Breakwaters: From Sea to Shore - Meeting the Challenges of the Sea, pp 1261-1271, 2014 [4] N Nik Hassan, S Wahid, and M Abd Wahab, “Geotechnical challenge in construction of coastal protection structure on soft marine clay,” The 17th Australasian Coastal and Ocean Engineering Conference 2005 and the 10th Australasian Port and Harbour Conference, COASTS and PORTS, pp 417-421, 2005 [5] S Rao, A Hegde, G Dwarakish, J Prashanth, and D Reddy, “Seawalls: Performance and their failure analysis along Southern Karnataka, West Coast of India,” International Journal of Earth Sciences and Engineering, vol 5(1), pp 18-29, 2012 [6] User manual Geostudio, 2007 Received: Revised: Accepted: 09 January 2018 18 January 2018 22 January 2018 Journal of Marine Science and Technology No 53 - January 2018 29 ... the shoreline by the soil stabilized block covered by polypropylene bag is highly feasible Structural solutions for dike with stabilized soil cover by Polypropylene bag are based on the following... Province before construction of dike Figure Layout of stabilized soil bags Figure Construction of dike using soil stabilized covered by Polypropylene bag in Tien Giang Province Figure Schema of dike. .. stabilized soil bag to build dike Figure Coastal embankments were constructed using Polypropylene bag filled with stabilized soil The steps for calculating an embankment structure using stabilized soil