NANJING WANHUI NEW MATERIAL TECHNOLOGY CO.LTD

When a project decides to use sheet piles, selection of the right sheet pile profile needs a careful examination of all the alternative sections available in order to reach an optimised solution to the design requirement.

It is unique, as unlike other steel sections, sheet piles do not have standard sections produced by all manufacturers. They produce different sections with different sectional properties. Cross sections are not common.

Selection of sheet piles starts with the design calculations after reaching a particular bending moment requirement. A sheet pile section would be designated with certain elastic section modulus and grade or quality of the steel material.

The bending moment carrying capacity of the section is directly proportional to the multiplication of its elastic section modulus and permissible stress depending on the grade of the steel material. For instance, a contractor or a project owner can choose a section with lower elastic section modulus and higher grade of steel in order to achieve a required bending moment carrying capacity.

Selection of lower elastic section modulus in combination with higher steel grade would lead to a lighter section and thus saving in material and total cost.

Of course, a higher grade of steel would cost a little extra. However, the saving in terms of material consumption and total cost is much higher than the incremental cost attributed to the higher grade.

These days, higher grades like S 430 GP are available without a big cost difference over normal grade of the steel. They are also advantageous in terms of greater resistance to the hard strata and driving obstacles, leading fewer deformations to the section and hence ensuring a high number of repeat uses.

Two more aspects are worth mentioning. They are higher width of piles and quality of interlocks. Higher pile width results in less number of piles to drive, would lead to saving in installation efforts and cost. It also reduces the number of joints, thus contributing to making the wall more water tight.

Quality of interlocks plays an important role when selecting the right sheet pile profile. By ignoring this, the wall becomes vulnerable to weakness.

The wall would be less water tight and migration of soil particles is possible from one side to the other during variation of water levels, in the case of tidal areas. Interlocks should not be loose and there should be proper gripping at the joints. Otherwise, declutching would appear.

Selection of the right steel sheet pile profiles has proven to be the best solution for retaining structures. With proper selection, steel sheet piles are the most economical solution.