The HZ^®-M Steel Wall System is a combined wall created by the combination of several elements. It replaced the older HZ system in 2008, and comprises following elements:

• HZ^®-M king piles (primary elements), a special wide flange beam with a specific flange geometry, and a width of 420 mm or 460 mm,
• AZ^® infill sheets (secondary or intermediary elements), standard corrugated steel sheet piles,
• special hot rolled connectors (RH, RZD, RZU) connecting infill sheet piles and HZ-M king piles to guarantee a continuous wall.

This system has a high bending resistance and stiffness. The king piles can also be used as bearing piles submitted to high vertical loads, e.g. loads from cranes on quay walls. The intermediary sheet piles (or "infill sheets") act mainly as soil-retaining and load-transferring elements. Their main task is to transfer the horizontal loads (soil pressure, water pressure,...) to the king piles, and are usually between 60% and 80% of the length of the king piles.



The HZ-M/AZ systems achieve very high stiffness and high bending moment capacity. Depending on the combinations and steel grades adopted, the bending moment capacity can reach more than 21 000 kNm/m (equivalent elastic section modulus W_el up to almost 46 500 cm³/m).

The numerous available combinations are based on the same principle: one structural support comprising 1 or 2 HZ-M king pile sections, alternating with a lighter intermediary double AZ sheet pile. There are also combinations without AZ infill sheets. Note that the infill sheet shall always be one AZ double pile.

Infill sheets are generally shorter than the HZ-M king piles. Depending on soil conditions and additional design criteria, such as durability, AZ infill sheets have usually a low section modulus (typically AZ sections with an elastic section modulus W_el up to 3 000 cm³/m).

Hot rolled RZD, RZU and RH connectors threaded and partially welded to the HZ-M king piles allow a mechanical connection with the AZ infill to form a continuous wall.

ArcelorMittal manufactures a series of four HZ-M profiles, and three of them can be rolled in three or four different thicknesses. Additionally, there are six different ‘solutions’ for each HZ-M section.

One of the key features of the HZ-M king pile is the concave geometry of the flanges of the lighter HZ-M sections, as well as the unmatched flange thickness of the heavier king piles. To thread the RH/RZ connectors, a groove is milled into the flange (patented process). The milling equipment guarantees very tight tolerances of the shape of the groove, which improves the minimum interlock hook connection and ensures a sufficient residual steel thickness t₃ on the flange (see picture). Note that the groove is milled only if required, i.e. sol. 12 and sol. C1 have only grooves on one flange.



Note: HZ^®, HZM^® and HZ/AZ^® are registered trademarks of ArcelorMittal.