What is the proper vinyl sheet pile driving method for different soil types?

“Pitch and drive” method is the most practical way of pile driving in loose soils especially when using short piles. Also called “set and drive”, this method installs piles one by one. However, with only one interlock in control, sheet piles have high tendencies of rotating from the axis and leaning forward or backward. Panel driving is recommended for the dense deposit of sands and compact cohesive soils such as heavy clay or in presence of obstructions. In this method, a number of piles are interlocked together before driving. The panel of piles is supported by guide frames and driven gradually in sequence, sometimes in a staggered manner. The method can achieve installations of longer piles in more difficult ground conditions with better results in sheet pile alignment and verticality. In cases of difficult ground conditions such as hard strata and the presence of obstructions, driving assistance is employed along with a proper selection of driving method and equipment. Jetting and drilling help by loosening or eliminating obstructions by creating pressure right under the tip of the sheet pile being driven. Long and slender PVC sheet piles require steel mandrels as supports when driven in such conditions. Mandrel, which shape is similar to sheet pile profiles, increases the rigidity of Plastic Sheet Pile and supports the weight of the driving equipment such as a vibro-hammer.

What is the proper machine to drive piles in different conditions?

Impact driving is suitable for all soil types but appears to create the highest degree of stress to sheet piles. It is more appropriate to cohesive soils and soft soils such as silts and peats, loose medium to coarse sand, and gravels free of rock inclusions. Drop hammers such as the hydraulic hammer are the common types of impact-driving machinery. Driving using vibratory hammers is ideal for non-cohesive or granular soils such as soft soils and round-grained sand or gravel. It has also shown satisfactory performance in sandy, silty, or softer clay soils. It is less effective in angular-grained materials and soils with a firm consistency. With the introduction of vibration, however, the sub-soil can be further compacted, increasing penetration resistance and ultimately-refusal. If this is the case, driving aids like jetting and drilling might be necessary.

What are the pvc sheet pile selection criteria for soil condition of different hardness?

General rule of the thumb: “the harder the soil, the stronger and stiffer sheet pile section should be used”. Driveability of a pile section is a consequence of its cross-sectional properties (thickness, depth, and width), designed shape, length, grade, and the applied load. Hardness of soil strata characterized by SPT or CPT values is used to predict soil resistance which is essential in the calculation of driving force to be applied. Knowing the range of force from the selected driving machine, corresponding sheet pile sections can be picked according to their yield strength and elastic modulus.

How should I choose a sheet pile section for soils with, say, SPT Value, N=30? Can I still consider using vinyl or shift to steel?

Every sheet pile material has a design purpose, strengths, and areas of improvement. The availability of different materials denotes the need for a special material for a specific application. Plastic or synthetic sheet piles for example are known for being light and corrosion-resistant; Steel sheet piles are recognized for their extraordinary strength and versatility; and so on.

ESC Group
- Oct 28, 2022
- 3 min read

Understanding Mono-Extruded and Co-extruded Vinyl Sheet Pile

Vinyl sheet pile or also called synthetic and plastic sheet pile is an innovative earth-retention and excavation-support material alongside steel, concrete, and treated wood. Besides its high level of durability and aesthetics, it is proven to be the most sufficient and cost-effective option for hydrotechnical engineering and construction applications especially seawalls & waterfronts, flood control, and bulkheads.

Vinyl sheet pile is made from modified PVC (polyvinyl chloride). It is produced by grinding and melting recycled PVC compounds along with refining ingredients (hardness modifiers and thermal or UV stabilizers), forcing it through a mold where it takes shape, cooled, and then cut to desired lengths. The forming process is called extrusion.

Extrusion of vinyl is done in two ways – mono extrusion and co-layer extrusion. Both mono-

extruded and co-extruded vinyl sheet pilings creates high-quality sheet pile walls. In a glance, they may appear the same but actually have significant difference to both manufacturer and consumer’s end.

Mono-extruded Vinyl Sheet Pile

Mono-extrusion is a traditional process of forming different shapes and sizes of vinyl sheet profiles from single layer of material. From the word “mono”, it is composed of only one material from the core to its surfaces.

Advantages:

1. It only requires one extruder so fixed-asset investment is less.

2. Involving only one material and extruding machine requires lesser technical expertise to run production.

3. When scratched, the color remains the same because of its consistent composition from outer layer to the core.

Disadvantages:

1. Due to one-material composition, the core of the sheet pile has the same ingredient as in its outside surface. This makes mono-extruded vinyl profiles considered unnecessarily expensive because ultraviolet (UV) inhibitors, typically the most expensive ingredient in the mix, are present in the core where they are actually useless.

2. Color of mono-extruded vinyl sheet piles can vary from batch to batch of production due to variety of raw material sources.

Co-layer or Co-extruded Vinyl Sheet Pile

Co-extrusion is a modern process in producing vinyl sheet piles that works by extruding two compounds at the same time to form a desired profile. It typically involves using a cheaper substrate material to give the sheet its mass and a more superior outer layer called “capstock” to protect the exposed surfaces primarily from UV radiation.

ESC Group (Middle East) - Fabricator, Supplier & Contractor in the Middle East & Africa

ESC Global:

Understanding Mono-Extruded and Co-extruded Vinyl Sheet Pile

Mono-extruded Vinyl Sheet Pile

Co-layer or Co-extruded Vinyl Sheet Pile