Drive Piles Efficiently with Pile Driving

Pile driving is often used to construct foundation supports for buildings and other structures. It’s also possible to use the process to install fencing, erosion control barriers, and signposts. It’s an efficient and quick way to install deep foundations and causes minimal disruption to the surrounding area when performed with pile drivers.

What are the Advantages of Pile Foundations?

Here are several advantages of pile foundations:

• You can order it in advance
• It’s highly customizable
• Shortened the building time
• Suitable for any size of land
• Ideal for deep installations
• Best for wetlands
• Long-lasting
• Suitable for places where it’s hard to drill and make holes

What are the Disadvantages of Pile Foundations?

While they have many advantages, there are also several disadvantages to pile foundations, including:

• It can get damaged by stones
• It would be below or at ground level
• You have to be careful about the size of the pile foundation
• It doesn’t have drainage

Parts of a Pile Driver

A pile driving system is composed of four main components: lead, hammer cushion, helmet, and pile cushion. Together, they work to transfer energy to the piles, which impacts how well the hammer performs.

Lead

The pile driver lead is a support beam that guides the piling and hammer. Depending on how they are suspended from the pile driver, they are either hanging, fixed, or swinging. Leads keep the pounding and hammer in sync.

Hammer Cushion

A shock-absorbing hammer cushion, usually constructed from man-made materials, is positioned between the striker plate and helmet.

Helmet

Helmets are steel caps placed atop piles. It protects the head during driving.

Pile Cushion

A pile cushion is usually made from wood and serves as a buffer between the helmet and the pile.

Types of Pile Drivers

Pile drivers come in several types, such as:

Vibratory Hammer

Vibratory hammers slice through the soil to create piles rather than pound them using a spinning and counter-weight system. Hydraulic motors provide the power for this operation while a crane or excavator lifts the hammer. The pile is attached to the vibratory hammer via hydraulic clamps. Creating piles is faster and emits less noise (comparatively).

Diesel Impact Hammer

A two-stroke diesel engine powers this drop hammer. The operator raises the ram, then drops it onto the pile. As the ram hits the pile, its momentum drives it back up. The machine will continue until the fuel runs out or it’s manually stopped.

Double Acting Air/Steam Hammer

With a shorter stroke, these hammers increase the blow rate when the ram is accelerated during the downstroke, and pile-driving speed increases.

Hydraulic Impact Hammer

A hydraulic hammer employs an outside power source to raise the hammer to the top of its arc. For a single-acting hydraulic hammer, the energy that drives the piston down comes from gravity, like a drop hammer or a single-acting air/steam Hammer.

Pile Driving Common Challenges and Solutions

The inherent challenge of pile driving is that it deals with soil and that there are a lot of potential problems with this setup. But if you plan and consider all the likely issues that come with pile driving, you can be better prepared to mitigate them. Include solutions in your contingency planning, so you don’t exceed the budget, among other issues. Here are some common challenges and solutions:

Pile Needs More Blows to Drive

Before starting, calculate how many times the pile driver needs to hit the ground to make the pile as deep as required. It depends on the soil and the driving system. If it takes more hits than we thought it would, there is a problem with the soil or the driving system.

Always match the driving system to the pile type before starting any work. If already matched, verify that the driving system operates according to the equipment manufacturer’s guidelines. Inadequate driving system performance can be due to insufficient hammering efficiency or too-soft cushioning. The soil may have more strength, a higher damping ratio, or larger soil quakes than initially tested for.

Bearing Piles Have a Sudden Change Blow

Borings must be taken if the blow count of a group of pilings changes. The pile toe is likely damaged if there is no indication of a weathered profile above the bedrock. If the pile is too damaged to inspect from the inside, use dynamic measurements to evaluate the problem. If that is not possible, you will have to extract the pile.

Slightly Lower Blow Count

There are two possible explanations for a lower-than-anticipated blow count: either the soil’s resistance is low, or the performance of the hammer is better than average. If soil resistance is lower than anticipated, you will need restrike testing. It entails calculating the setup factor and driving at a reduced capacity. Evaluate hammer performance and make adjustments as required.

Significantly Lower Blow Count

If the blow count is lower than expected, check the soil borings. The pile may be broken beneath the grade if there’s no sign of soft layers. In addition to evaluating the tensile stresses along the pile, you should also check for compressive stresses at the toe. Some other possible causes of this issue include a spliced pile, an obstruction, or uneven contact at the toe. Inspect the toe area for any damage that may have occurred.

Piles are Going Deeper Than Expected

A restrike test is needed to discover any soil strength changes. If deeper piles are driven into the soil than initially estimated, it may be because of lower soil resistance than anticipated. Or, it could be due to increased driving system performance. A structural engineer will then determine if changes need to be made in the driving system or pile depth.

Shifting Piles

If the piles unexpectedly move, it’s a sign that an issue needs to be fixed before work can resume.

Lateral Movement in Previous Driven Piles

The piles have likely failed due to soil displacement if they move laterally when new piles are being driven. However, the failure may be coming from an adjacent slope. To solve this issue, you can change the sequence of pile driving or re-drive the installed piles. You may also be able to reduce ground movement by predrilling pile locations.