ArcelorMittal Projects, ArcelorMittal Europe – Long Products Sheet Piling, and Global R&D participated in a project financed by the Dutch government to improve the design of dikes and keep the Netherlands safe from flooding.

Exploring economical and innovative solutions for safety

The Netherlands is a low-lying country protected from the sea by dikes and dunes. For decades, dike reinforcements have been installed to keep the country dry and prevent floods from happening. Due to continuously increasing safety demands and loads, one third of Dutch dikes do not meet safety requirements.

Macro-instability is one of the most common causes. It can occur when a high water level pushes against the embankment. This causes saturation of the soil and loss of stability resulting in large parts of the dike body sliding away.

When there is a lack of space due to cultivation around the dike, reinforcements to prevent macro-instability are utilised. Dikes with steel sheet pile walls are very strong and do not have to be widened thus reducing objections from residents and time-consuming judicial procedures.

Given the Dutch safety challenge, the need for cost saving has risen over the last couple of years. The government is making a tremendous effort to search for innovations that will allow for the necessary cost saving.

Taking part in the governmental study team

To investigate how the sheet pile design standards can be optimised, the government decided to finance dike tests in Eemdijk in the province of Utrecht.

The tests focussed on gaining a better understanding of the interaction between the soil and the steel sheet piles. A team consisting of ArcelorMittal Projects, ArcelorMittal Sheet Piling, and the R&D department contributed to the design process. ArcelorMittal also provided GU8N and AZ26-700 sheet piles for the tests. They were produced by ArcelorMittal's sheet piling mills in Dabrowa, Poland and Belval, Luxembourg.

The choice of the sheet pile profile in combination with the steel quality was crucial for a successful test. All dimensions of the sheet piles were extensively tested to ensure an accurate mapping of the profile characteristics. Additional tensile tests were performed to determine the exact mechanical features.

This testing program was part of the Project Transcending Exploration Macro stability (POV-M)*, which is under the Flood Protection Program (HWBP)*. The tests even gained attention at the international level from the US Army Corps of Engineers to delegates from South Korea and China.

*The sheet pile tests were executed in cooperation with Waterboard Vallei and Veluwe, Deltares, Witteveen+Bos, Fugro, and ArcelorMittal.
**A cooperation between Rijkswaterstaat (The Ministry of Infrastructure and the Environment) and the water boards.

Test setup and process

At the Eemdijk test site, an oval shaped dike of 5m high, 60m long, and 40m wide was constructed in six months’ time. The dike was fitted with measuring equipment and was only used for this experiment which helped to increase knowledge of soil-structure interaction. After the tests, the dike will be completely removed. A total of three tests have been performed at the site with our sheet piles produced in Dabrowa and Belval.

Full Scale Test Green Dike: This part of the dike was constructed with a sand core and an outer cover layer of clay. The groundwater level inside the core of the levee was slowly raised to +2.80 metres, at which moment a sliding plane occurred and the dike collapsed. This test acted as a baseline measurement which was used as reference for the final test.

Pull Over Tests: Four different sheet pile configurations were installed 14 metres into the ground after which they were pulled over with a hydraulic cylinder. The objective was to see at which force level (with a maximum of 100 tonnes for AZ26-700) and which deformation the sheet pile wall would collapse. Additionally, the four configurations gave insight into the differences in the behaviour of a continuous wall and loose panels and between the elastic and plastic behaviour of the steel sheet piles.

Full Scale Test Blue Dike: This part of the dike was built similarly to the green dike apart from the reinforcement, which was over 60 metres with GU8N sheet piles. These piles were placed as triplets and staggered with lengths of 18 and 9 metres. This test was a combination of the above-mentioned tests and was the main test of the research.

A 2-metre-deep ditch was dug at the bottom of the blue dike. The groundwater level in the dike body was slowly raised and the filling of the water basin behind the levee was carried out over time. This led to a water level at the crest of the dike located at +5 metres. In addition, seven containers filled with water were placed on top of the dike, creating an extra load of 40 tonnes per container. Despite the combination of the huge loads, the steel sheet pile reinforced dike refused to give way.

By infiltrating the landward slope of the levee and lowering the water level in the ditch, the dike finally collapsed. Two million litres of water flowed out of the basin into the hinterland highlighting the success of the tests.

Saving 20-30% of steel

The dike, reinforced with steel sheet piles, finally collapsed but only after putting an extreme load on it; not collapsing the dike would have resulted in a less successful test.

Results of the different tests were in line with realistic predictions which are even more favourable than current calculation rules. This concludes that steel sheet pile walls are an extremely strong and practical solution for dike reinforcements.

Existing dike reinforcement projects cost an average of 15 million Euro per kilometre of dike. It is estimated that with these updated design rules, 20-30% of steel can be saved in new projects. With this cost savings, it is anticipated that the market share of the “innovative” steel sheet piles will increase in future dike reinforcement.

Text: ArcelorMittal Europe Communication

Copyrights: © POV Macrostabiliteit

In total, more than 9.000 tonnes of steel sheet piles manufactured in Luxembourg were delivered for the construction of different harbour infrastructures in 2009 and 2012 and definitely contributed to the completion on time of all the infrastructure and civil works for the Sochi Winter Olympics 2014.

Sochi is a city of around 400.000 people situated in Krasnodar, the third largest region in Russia, and hosted the Winter Olympic Games in February 2014.

The new port consists of a new breakwater, around 1,200 m long, which is also utilised in a first phase as a quay wall on approximately 520 m. On the land side, a new 800 m long quay wall was built.

The main mission of this infrastructure is to allow transhipment of bulk construction material used for the erection of the new buildings and sports arena. After the Olympics, a portion of this new port structure will be rehabilitated and transformed into a marina to accommodate small size boats and yachts.

ArcelorMittal shipped the sheet piles from its Belval mill in Luxembourg to Antwerp, loaded them on vessels that sailed directly to the existing Port of Sochi. The material was then trans-shipped into smaller barges, and shipped to the new port.

The layout of the breakwater is a concrete deck on piles, with a gravity type breakwater on the sea-side. The aim of the selected AZ 19-700 sheet piles is to act as an impervious wall and stop the water flow through the breakwater, as well as to reinforce the earth retaining structure. The quay wall is built as a typical anchored wall, with a main wall and anchor wall in AZ 37-700 fixed with steel tie-rods. The draught level is -9.20 m.

Some 8.220 tonnes of sheet piles in lengths from 8.0 m up to 30.5 m and in high steel grade S 430 GP were shipped between June and October 2009 in three lots. The sheet piles were then coated in a workshop inside the port. Sheet piles were driven into the ground with vibratory hammers, and fixed on top and at the water level to the steel tubes through a waler.

The main advantage of the sheet piles against alternative solutions was the very short execution time and the quite rough weather conditions at the job-site, especially in winter. In fact, it was mainly the weather conditions in the coastal area that lead to such a rigid solution for the breakwater.

Our sheet piling department works predominantly on projects in collaboration with the end users and stakeholders. YUGTranstroy (subdivision of Transtroy) was the general contractor and the installation was performed by BMGS, one of the largest Russian construction companies.

The AZ 19-700 and AZ 37-700 are the most efficient sheet piles worldwide in their range and they are exclusively produced at Mill 2 in Belval, Luxembourg.

The second project was located in the old Port of Sochi, close to the city. The new structure serves as a passenger terminal capable of accommodating large cruise ships during the Olympics. Two wharfs were built with sheet piles: the Federal Security Service harbour wall, and the Federal Custodial Service harbour wall, using mainly AU 25, in steel grade S 355 GP, length of 20.4 m (around 720 tonnes), AZ 26-700 and AZ 13-10/10 in lengths up to 8 m (around 160 tonnes). These sheet piles were shipped by vessel directly to the Port of Sochi in July 2012 in a single lot.

The design engineering company for both projects was MST (MorStroyTechnology), a renowned Russian company from St. Petersburg.

Pictures: ArcelorMittal RPS
1. Port Sochi Imeretinskaya, Cargo Terminal
2. Typical cross section of the quay wall
3. Quay wall

Deptford Creek is a tributary of the Thames in London inside the Thames Barrier. In order to protect an estimated 33 000 households from flooding, the Environment Agency identified five Wharves along Deptford Creek for immediate replacement. Existing anchored timber pile structures were assessed to be reaching a stage where failure was imminent. The five identified locations were Kent Wharf, Ash’s Wharf, Thanet Wharf, Hilton’s Wharf and Saxon Wharf. 

At the highest frontage the 109 m long Hilton’s Wharf has a retained face of 7 m. Future development plans for the site precluded the use of permanent anchors to support the new wall and so an innovative solution facilitating a composite wall system (propped structure) was engineered by Jacobs / Volker Stevin.

The new wall was to have a 100 year design life and was to embrace the objectives of the Biodiversity Action Plan. The solution consists of a steel sheet pile wall made of around 1 040 tonnes of AZ 41-700 in grade S 430 GP steel grade, and in 16.5 m up to 17.5 m lengths. These are supported by a row of 12 m long 305x223 HP bearing piles driven at a 10 degree rake in front of the sheet pile wall, with timber planking spanning between each HP pile.

A mass concrete block was then poured between the sheet piles and HP piles lines down to the excavated depth, exposing the gravel layer, such that the structure acted in unison. The top of the concrete block level was Mean High Water Neap (MHWN) level such that he planting area above could offer maximised value of environmental habitat.

The construction of this innovative “composite cantilever” sheet pile wall presented its own challenges in that the working space was limited to only 10 m behind the existing old walls which were in such poor state that they could not support construction surcharges. Besides, in some places the existing wall could not be subjected to vibration from conventional installation techniques.

To accommodate these requirements the AZ 41-700 sheet piles were installed behind the existing structure by an ABI Vibrator MRZV-V (variable frequency) on a leader rig, or where vibration was to be minimised, the subcontractor Stent / Giken used the Giken Crush Piler ECO 700S with a press force of around 100 tonnes. This pressing equipment incorporates an auger to bore ahead of the pile toe before the press pushes the piles down in combination with water-jetting.

The sheet piles were then tied back to a temporary deadman (concrete block). A specialist bridging mat was then installed, spanning from the deadman to the sheet piles and avoiding any surcharge on the ground behind the main wall. From this mat the excavator could remove the old timber structure and dig down to expose the gravel layer. Additionally, the HP raker piles could also be installed from the bridging mat. After fitting the timber planking between the HP piles mass concrete was poured between the walls which when cured bound the wall and the supporting HP pile wall into a kind of “A frame” composite structure.

The deflections measured during the temporary stage were lower than predicted in the design calculations. The criteria for deflection during the final phase is 200 mm at ULS with a surcharge load of 20 kPa behind the wall. A static reserve of steel thickness was taken into account in the design in order to achieve the design life. No surface treatment was implemented.

The condition of the existing walls, the site area restrictions, the requirement for a cantilever solution and duty of care to the Natural Habitat combined to pose quite a complex problem. Jacobs Engineering with early contractor involvement from Volker Stevin, adopted a combination of steel sheet piling and steel bearing piles to form a structure which elegantly met all technical and economic aspects of the project.

Text: ArcelorMittal Commercial RPS

In the last years, severe floods caused by storms and heavy rains have increasingly shaken the whole world and have shown that flood protection continues to be an important topic. In order to minimize flood damage, significant investments are required in this area – and steel sheet piles offer an efficient solution for flood control and riverbank protection.

Efficient flood protection systems with sheet piles

In order to establish an efficient anti-flood system, apart from creating a polder system with flood plains, land reclaimed or marshes, it is necessary to take some integrated activities within the range of the environmental development and construction strategy. It is essential to build a relationship between modern technology solutions and the potential of the natural environment itself.

The implementation of steel sheet pile jagged walls is the safest and the most cost-effective solution. The sheet piles are the best answer for building and reinforcing flood dikes, ditches, etc. Their high tightness coefficient is well-known and tested in practice. The ArcelorMittal sheet piles, either hot or cold rolled, are an appropriate and optimal solution for the problem. Self-propelled high frequency vibrators and hydraulic machines are used for the sheet pile caving. This way there is no environmental damage.

A short installation time allows the use the sheet piles just before the flood arrives. It is possible to use them in many ways, taking into consideration the evaluated and real loads.

Steel sheet piles offer numerous benefits in flood protection

1. Sheet piles can seal and stabilize both existing and new flood dikes. They prevent tides and stabilize the structure of flood dikes. The combined wall is an impassable barrier for animals and tree roots and prevents landslides. The part of the wall seated into the ground is corrosion-resistant — under normal conditions it is assumed that the wall thickness decrement reaches 0.03 mm per year, 1.5 mm per 50 years (source: Eurocode 3. Design of steel structure. Part. 5 Piling).

2. Another benefit of using sheet piles within the range of flood protection is the material as itself: Steel is homogenous, flexible, plastic and safe for the environment. The material meets the requirements of well-known standards (EN). Steel is 100% recyclable — it is 100% "ecological" material.

3. Steel jagged walls are provided as ready-to-use products for immediate application. Some construction transformations like replacement, caving depth increase, sheet piles joining, may be operated at any time. It is possible to use various sheet pile types within the scope of the given project and to join them in order to make the structure unbroken and optimize the investment costs.

4. Sheet piles are one of the solutions for ditch (flood dike) tides. Whereas other construction materials yield easily, it is impossible to break a sheet pile structure. The ArcelorMittal sheet piles, used in anti-flood structures all over Europe, prove that they are a fast and cost-effective solution.