Steel sheet piles can easily be combined to form special arrangements and create systems with large bending resistance. Combined walls built up with box piles (or HZ-M, or steel tubes) and standard sheet piles are one of these solutions.

The primary piles, or “king piles”, of combined walls can also be used as bearing piles. and can bear high vertical loads, e.g. crane loads. The intermediary sheet piles act mainly as soil-retaining and load-transferring elements.

The equivalent elastic section modulus W_sys per linear metre, respectively per linear foot, of a combined wall is based on the assumption that the deflections of king piles and intermediary steel sheet piles are the same, leading to the following formulas