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

Jun 3, 20234 min read

Pile Extraction Equipment and Methods

Updated: Sep 23, 2023

Sheet piles, trench sheets, pipe piles, and other types of temporary pilings are retrieved from the ground for recycling or re-used. Regardless of the kind of material, extracted piles can be used in other piling works, and in different construction applications, or sent back to recycling plants for reproduction in the case of plastic and steel piles.

Pile extraction is commonly done by either vibratory or ‘press-in’ method which is also known as ‘silent piler/extractor’. Retrieval of piling elements, especially in tougher situations can also be aided by water-jetting or excavation/augering.

PILE EXTRACTION BY VIBRATION

Ground-driven piles are extracted using vibratory equipment that induces oscillation to the pile element to reduce friction against the soil while being pulled-out. Pile extraction using a vibratory hammer is done in two plant options: crane-suspended vibro-hammer or excavator-mounted vibro-hammer.

Crane-suspended Vibro-Hammers – are designed to drive and extract all types of piles such as sheets, tube casings, H-Beams or I-Beams, and more. It is commonly employed for construction projects such as harbors, airports, railways, bridges, and canals. They are also favored for infrastructure projects in urban environments such as pipelines and other utility works. Crane-mounted vibratory hammers are ideal for any large soil reinforcement and stabilization applications.

Here are some advantages associated with these types:

- High performance

- Can drive or extract all kinds of piling profiles and sizes

- Various clamp types to suit all pile profiles

- Time and cost saving

- Can be used under-water

- Powerful, reliable, and longevity.

Excavator-mounted Vibro-Hammers – also has the ability to drive and extract variety of piling profiles such as sheet piles, H-Beams, and I-Beams. Larger hammers with special fittings such as a double clamp can also work with pile casings and tubular piles using an excavator. Vibro-Hammers are highly compatible with the hydraulic mechanisms of excavators requiring no modification to work efficiently.

Some of the notable advantages of excavator-mounted vibro-hammers are as follows:

- Fast and easy excavator connection

- High-performance and extracting power

- Minimal vibration transmission to the surrounding

- Mobility

PILE EXTRACTION BY ‘PRESS-IN’

Hydraulic-operated ‘silent pile extractors’ are vibration and noise-free pile extraction devices suitable for retrieving a wide range of pile types from a variety of ground types. These types of pile extractors provide alternative solutions to crane and excavator-mounted vibro-hammers in cases of difficult working environments such as narrow spaces, low headroom, bodies of water, and in areas where noise and vibration are controlled.

The principle of pile extraction using hydraulics can be put simply as jacking up a car using a hydraulic jack. There are two types of hydraulic pile-extraction machine - one that utilizes base plates and generate upward force by pushing against the ground and one that clips itself at driven piles to create an anchor while pulling up the piles. Hydraulic machines that employ base plates rely on the bearing capacity of the ground or its platform.

In the case of soft or saturated soils, wider bases are required to create adequate resistance equivalent to or greater than the necessary amount of force to take out sheet piles and other profiles. Besides, ‘pitch and extract” hydraulic machines depend on the driven piles as footings. During extraction, the machine grips a group of pile heads alongside and pushes against it to lift the target pile. This means that further penetration of the anchor piles during this action is also a reduction in the lifting power of the machine.

Below are some of the key benefits and advantages:

- Allow pile installation in environmentally sensitive areas

- Virtually no noise or vibration was generated during sheet pile installation

- Can be equipped with piling aid mechanisms such as water-jetting and pre-augering

- Eliminates working at a height

- Suit site constraints and difficult ground conditions

- Effective for both sheet pile installation and sheet pile extraction

FACTORS AFFECTING THE SELECTION OF PILE-EXTRACTING EQUIPMENT

The ideal type of piling equipment to employ in a pile extraction project will depend on a few things:

Type and size of the extracted pile

For smaller sizes of piles such as trench sheets, sheet piles, and small piles, excavator-mounted vibratory hammers would suffice. For bigger sizes of piles such as tube casings, king piles, H-beams & I-beams, and crane-suspended vibro-hammers is recommended

Ground conditions

Normally, hydraulic or silent pilers are effective in both granular and cohesive soils demonstrating a pressing force of up to 150 tons for pile installation, and 160 tons for pile extraction, generated using previously installed sheet piles as a source of reaction force. In tougher ground conditions such as dense granular or stiff cohesive soils, auxiliary techniques can be incorporated to facilitate easier extraction. These include pressure water jetting or pre-auguring.

Ground condition is basically the most important parameter of a piling job whether in pile driving or retrieval. It is best to seek professional expertise in this matter regardless of the size and complexity of the project. Explore the best options from one of the best in the global market, visit www.escpile.com, and hear from the expert’s perspective.

Surrounding or environment

Construction sites located in sensitive areas require control measures to mitigate distractions and hazards like noise, vibration, and clouds of dust. Within the premises of city centers, hospitals, residential blocks, schools, and other delicate neighborhoods, the use of vibratory hammers is not advisable. Though excavator-mounted vibro-hammer creates minimal noise and vibration, hydraulic or silent pilers fits-in perfectly in these scenarios due to virtually producing zero noise and tremor.

Accessibility

Each construction site has constraints that differ from one another. In extracting piles over water for example, to use a vibratory hammer mounted on an excavator, there must be a pontoon, so it is impractical. On the other hand, a vibro-hammer held by a long crane or a self-moving hydraulic press machine can finish the job efficiently and with ease.

In areas where the headroom is limited, vibratory hammers held by crane or excavator are obviously not an option. Hydraulic pile extractors are the correct choice. This also applies to narrow areas or wherever space is not enough to set up a crane or maneuver an excavator. Sloping grounds also limits the mobility and positioning of excavators, the arm length of cranes might come short for long reach, while the hydraulic pilers suites all kind of terrains.

For further assistance, please send your piling inquiries to www.escpile.com. ESC is a globally recognized provider of superior products and services. We take pride in catering to your diverse needs - ensuring your satisfaction. Allow ESC to be your trusted partner in fulfilling all your requirements.