Combination Wall Solutions A high strength system combining maximum stability with economical weights

A combination wall is a high-strength retaining system that uses regularly spaced structural king piles together with intermediate sheet piles. The king piles provide the main bending and load-bearing capacity, while the sheet piles span between them and retain the ground. This arrangement can provide greater strength than a conventional sheet pile wall.

Combination walls are typically considered where conventional sheet piles cannot carry the required loads, where large retained or dredge depths are involved, or where weak ground requires longer piles to reach competent strata. They are widely used in marine and heavy civil engineering applications, subject to project-specific design and installation constraints.

The two principal components are structural king piles—commonly HZM sections or tubular piles—and intermediate sheet piles. Clutch connections transfer loading between the elements. The intermediate sheet piles are often shorter than the king piles, with their required length determined by the wall design, ground conditions and retained height.

Combination walls can provide high bending strength with economical section weights, low deflection, increased vertical load capacity and strong lateral impact resistance. Suitable systems may also penetrate hard ground and accommodate substantial retained heights. The relevant benefits depend on the selected sections, ground conditions, installation method and structural design.

King piles carry the primary structural loads and may need to extend into stronger ground below the intermediate sheet piles. In marine applications, driving them deeper can increase axial capacity and stability where large dredge depths or weak seabed materials are present. The final pile lengths are established through geotechnical and structural design.

Useful information includes retained and dredge levels, structural and vertical loads, ground investigation and groundwater data, design life and corrosion requirements, site access, installation constraints, nearby structures and services, and the construction programme. We can assess these factors to develop an efficient system suited to the project requirements.