METHOD OF CONSTRUCTION FOR VINYL SHEET PILE (VSP)

1.   Preface

By the mid to late 20th century, as the drawbacks of traditional materials like timber (decay, marine borer attacks) and steel (corrosion) became increasingly evident, the search for alternatives gained momentum. Vinyl, with its inherent resistance to many environmental threats, presented a promising option.

The first vinyl sheet piles appeared in the market around the 1980s, offering an almost maintenance-free alternative to materials that had dominated the industry for decades. The adoption of vinyl sheet piles began to progress, especially in marine construction projects where long-term durability without intensive maintenance was a priority.

In recent years, VSP have started to gain increasing popularity. Their lightness, corrosion resistance, and ease of installation are just a few of the advantages that attract engineers and investors to choose VSP, especially when utilizing in seawall, bulkhead, and cut-off wall construction.

In this document, we will discuss the method of construction for VSP to ensure the installed VSP can meet the project requirement but also save the cost for the Contractor. This way, engineers and industry specialists will be able to make more informed decisions about choosing the construction method.

2.   Construction method

The construction method for VSP will be decided based on fully consideration of surface condition (on water or in land), hardness of soil strata, obstacles underground, designed length.

2.1.  Installation method and required equipment

Manual installation

For extremely soft soils and short drove length, simple manual tools (hammer/mallet) can be used to drive the VSP to designed depth with just few labours.

Installation by Backhoe

When installing VSP with the short length or soft soil, it is recommended to use the bucket of a backhoe to press down VSP to designed depth. To protect the pile head and also distribute pressing load steady to the pile, it is recommended to use a steel pile cap.

Installation by vibrohammer

When installing a longer length or the ground conditions are more difficult, it is recommended to use a vibrohammer. Normally, the Backhoe/crane mounted with vibrohammer shall be used.

Installation by mandrel and vibrohammer

When installing at a depth of more than 4M from ground or in harsh conditions, it is recommended to use a steel sheath with the same shape as the ecological sheet pile (mandrel) and vibrohammer to cooperate with the construction. The support of the mandrel can penetrate the harder soil faster and speed up the installation also protect the pile from damage.

v Other installation methods

+       Drop Hammer

A drop hammer is a mechanical simple driving method for driving vinyl sheet piles by lifting and releasing a falling drop hammer weight at low frequency.

+       Water Jetting

Water jetting may be used in conjunction with other installation methods where the soil is very compacted or cohesive. A high pressure jet of water (or sometimes air) is expelled from the base of the sheet pile loosening the soil as the sheet pile is driven through.

+       Pre-drilling

When installing sheet piles into marine conditions where there may be little or no soil covering the bed rock and it is necessary for the piles to penetrate sufficiently to obtain a toe support or the stratum of very hard soil, the pre-drilling is recommended to apply.

2.2.  Construction’s orientation

+       The piles will be driven with the T connection joint ahead to ensure of non-filled soil in C connection joint.

+       The Z type will be driven in pair in order to ensure the straight and orientation of sheet pile line.