Enerpac contributes to construction
of the High Speed Line South

Hydraulics play their part in construction of HSL viaduct
Slowly the huge steel shuttering structure creeps forward to the following set of pillars to cast once again

Slowly the huge steel shuttering structure creeps forward to the following set of pillars to cast once again an upper track surface for the HSL.

an upper track surface for the HSL. The viaduct of the high-speed line(HSL) takesin this way step by step shape in the South-Holland countryside at Bleiswijk. Hydraulics play an important part in the raising, lowering and relocation of the shuttering. Enerpac supplies the hydraulic systems required for this.

The High Speed Line South (HSL South) that is currently being constructed, is one of the largest infrastructural projects of recent years. Between Schiphol and the Belgian border the HSL Southern comprises 80 kilometre of new rail track and no fewer than 170 bridges, viaducts and tunnels. Part of the HSL South is a through rail viaduct over the A12 at Bleiswijk.

In the meantime many rows of columns (pillars) dominate the skyline. The ‘plant’ too, where the concrete upper surfaces are laid on which the trains will travel, is in full swing.

Cast in situ
The heavy upper surface sections for this high viaduct in the HSL is being cast in situ using a special shuttering system with which 35 metres of concrete upper surface can be laid at once. The shuttering system consists of a movable bearing steel structure of horizontal beams, uprights and four separate shuttering elements.

Unusual is that the shuttering structure is relocated and raised to the proper elevation in its entirety for each new upper section to be cast using hydraulics.

‘In some senses this application is comparable to the hydraulic Roller Lift that we developed’, says Hans Knol, responsible at Enerpac, specifically in the Benelux, for special projects that fall outside the standard hydraulic 700 Bar high-pressure programme. ‘With the Rollerlift it is relatively easy to adjust heavy steel tunnel shuttering systems on both the vertical and the horizontal plane and that is more or less what we are doing here.’

At the right height

The work on the HSL is naturally somewhat more complex.The upper surface sections are 35 metres long, 10 metres wide and weigh some 800 tons.

In the meantime many rows of columns (pillars) dominate the skyline.

The shuttering, and everything connected with it, is of course on the same scale. Every upper surface section of the HSL is supported at each end by three pillars. The shuttering structure is supported by the same number of steel uprights that are secured to these pillars during casting. Under each upright a double-operation hydraulic high tonnage cylinder has been installed with a lifting capacity of 100 ton and a stroke of 50 mm.

These cylinders, powered by 20 Titan pumps from Enerpac with a higher yield, are used to adjust the 160 ton ‘plant’ to height prior to casting and to allow it to decline slightly after casting in order to release the structure once more from the cast and hardened upper surface section.

After the structure has been raised hydraulically to the appropriate height, the uprights are secured on mechanical wedges. This relieves the cylinders during casting. The height difference in this case is only about 5 cm. Just enough to avoid contact with the concrete surface during relocation to the next casting location.

Hydraulic relocation

When the concrete upper surface section is completely hard, which takes a week, the shuttering is relocated to the next pillars.

The horizontal relocation of the shuttering panels long-stroke cylinders powered by a pump especially developed for this purpose with a yield of 20 litre per minute at a maximum operating pressure of 700 Bar.

The horizontal relocation of the shuttering panels length ways is conducted by steel cables and ‘long-stroke cylinders’.

These cylinders are powered by a pump especially developed for this purpose with a yield of 20 litre per minute at a maximum operating pressure of 700 Bar. The plates are first pulled some tens of centimetres apart in crosswise direction using 20 ‘hollow plunger cylinders’ each with a capacity of 10 ton and a maximum stroke length of 200 mm and developed especially for this purpose. This in connection with the necessary recesses around the pillars. Each of the four shuttering panels is relocated separately.

After the shuttering structure has been relocated in its entirety to the following section, the shuttering panels are united precisely to form a single unit.

’It is a kind of step-by-step plan’, explains Knol. ‘One panel is oriented relative to the upright and the others drawn to it one by one. That’s how you obtain one large shuttering system.’

Slide bearing principle
During relocation of the various steel elements of the shuttering structures, no bearings or anything similar are used, reliance being placed rather on nothing more than the slide bearing principle. The shuttering panels are fitted with steel slide plates and the steel beams over which they pass clad with a bronze strip. The entire structure, including the shuttering panels, is even positioned by eye. ‘It’s really a pretty simple story” as Knol points out. ‘But nevertheless efficient.’