When addressing foundation issues or structural requirements in new construction, understanding the most suitable foundational support system is crucial. Two of the most commonly employed deep foundation systems are the push pier system and the helical pier.
While both have their own set of benefits, the decision on which one to use often hinges on the specific needs of a project. Let’s compare push piers and helical piers, providing a comprehensive understanding of when and where each system is most effective.
Push Pier System
One of the foundational pillars of modern construction and remediation is the push pier system. A literal support system, push piers are the unsung heroes when it comes to rectifying structural issues stemming from unstable ground conditions. These piers have carved out a niche for themselves as reliable allies against the unpredictabilities of soil behaviors. But what exactly makes them so formidable, and why are they preferred in certain situations? Let’s delve deeper.
The push pier system’s very nomenclature gives away its operational methodology. These piers are “pushed” or driven into the Earth’s layers. The driving force behind this push? Hydraulic pressure. The goal is simple yet profound: reach the depths where the soil is stable or, in certain cases, the bedrock. Imagine trying to pierce an apple with a straw; you push until the straw is deep enough that it can stand on its own without wobbling.
Structurally, push piers exhibit a tubular design. These tubes, made of robust steel sections, are meticulously connected end-to-end. As the system is driven further into the ground, additional sections can be attached, ensuring the pier’s reach is not only deep but also securely anchored. The steel’s inherent strength and resistance to environmental degradations make it an ideal choice for such a critical role.
The raison d’être of the push pier system is to act as a mediator. They take on the weight of the structure and transfer it from the unpredictable, often weak, soils to the more reliable and stable layers beneath. Think of it as a relay race where the baton of “structural weight” is passed from the runner (unstable soil) who’s struggling to the next runner (stable soil or bedrock) who’s in a better position to carry it forward.
Key Features of the Push Pier System
Method of Installation
The push pier system utilizes the sheer force of hydraulic pressure. This pressure is harnessed to drive the piers into the ground. What’s notable here is the precision involved. As the piers are pushed further, the force exerted by the hydraulic equipment is continuously monitored. This isn’t just a brute force exercise; it’s a calculated one. By measuring this force, specialists can determine if the pier has reached a stratum capable of bearing the load above, thus ensuring a stable foundation.
Depth of Installation
One of the most commendable features of the push pier system is its adaptability in terms of depth. These piers don’t have a “one-size-fits-all” depth. Instead, they can be driven as deep as necessary until they achieve the desired load-bearing capacity. This makes them incredibly versatile, suitable for a multitude of soil conditions, be it sandy terrains, loamy substrates, or even clayey grounds.
Application
While the push pier system might seem like a panacea for all foundational problems, its most acclaimed use is in the realm of underpinning. Structures, over time, can experience settlement. This is especially true if they’re built on soils that are unstable. When this happens, push piers come to the rescue, providing the much-needed support and stability. By transferring the structural weight to deeper, more stable ground, they ensure that the building remains upright and intact.
Helical Piers
Unlike the push pier system, which is driven vertically into the ground, the helical pier operates with a twist — quite literally. Imagine a large-scale screw, and you’ve got the basic concept of the helical pier.
Helical pier is known for its distinct design. Central to this design is a shaft, which acts as the main body. Extending from this shaft are one or more helix-shaped blades, giving the helical pier its characteristic screw-like appearance. It’s this helical design that forms the core strength and functionality of the system. When helical piers are introduced into the ground, they aren’t just pushed; they’re rotated. This rotation, facilitated by the helical plates, is what grants the helical pier its stability. As these plates dig deeper and engage with the soil, they provide an anchor, making the pier capable of supporting significant structural loads.
A major advantage of the helical pier system is its adaptability. Different soil conditions, ranging from sandy terrains to rocky substrates, don’t deter the helical piers. This adaptability has made them a popular choice, not just for new constructions, but also for repairing existing structures.
Key Features of the Helical Piers:
Method of Installation
While the push pier system relies on vertical pressure, the helical pier installation is all about rotation. Employing hydraulic machinery, helical piers are systematically “screwed” into the ground. This isn’t a haphazard action; it’s a meticulously monitored process. The torque — or the force of rotation — applied during this installation is a critical metric. It’s not just about getting the helical pier into the ground; it’s about ensuring that the pier is installed with the right amount of force to guarantee its load-bearing capacity.
Depth of Installation
The depth to which a helical pier is installed isn’t arbitrary. Several factors come into play. The number of helix plates, their size, and the prevailing soil conditions are all considerations. The more plates, and the tougher the soil, the greater the torque required. When this torque hits the desired metric, it indicates that the helical pier is optimally positioned to shoulder the weight above it.
Application
The versatility of helical piers is commendable. While the push pier system is renowned for underpinning existing structures, helical piers have a broader scope. They’re employed in fresh constructions, ensuring the building starts on a firm footing. For structures that have seen better days and are exhibiting signs of distress, helical piers can offer much-needed support and stabilization. Beyond this, they’re also instrumental in constructing retaining walls, ensuring these barriers remain steadfast against the pressures exerted by the soil behind them.
Push Piers vs. Helical Piers
- Installation: While both systems use hydraulic equipment, the main difference lies in the method. Push piers are driven, while helical piers are screwed into the ground.
- Soil Displacement: Helical piers, due to their screw-like design, displace soil laterally, making them ideal for locations with minimal disruption. Push piers, being driven, tend to cause more soil displacement.
- Load Testing: With the push pier system, load tests are usually performed after installation, while helical piers are continuously load-tested during installation by monitoring torque.
- Versatility: Both systems are versatile in terms of application. However, helical piers often have a slight edge in varied applications due to their ability to be customized with different sizes and numbers of helix plates based on soil conditions.
- Weather Constraints: Helical piers can be installed in colder climates even when the ground is frozen, whereas push piers might face challenges under such conditions.
Which is Right for You?
The decision between the push pier system and helical piers boils down to the specifics of the project:
- For structures that have settled and need immediate stabilization, the push pier system might be more appropriate.
- In areas with varied or unknown soil conditions, helical piers might be preferable due to their adaptability and the continuous load testing during installation.
- For new constructions where minimal soil disruption is required, the helical pier is often the go-to choice.
- It’s always recommended to consult with a foundation specialist or structural engineer who can evaluate the specific conditions of the site and make an informed recommendation.
Both push pier systems and helical piers have their own set of advantages and potential applications. Understanding the core differences, alongside the unique demands of your project, is key to making an informed decision. Whether you opt for the driven stability of the push pier system or the screw-like precision of helical piers, ensuring the right foundation support is paramount for the long-term safety and integrity of any structure.
If you’re confused to make the choice, let FoundationMD help you with it! We’re experts of what we do and our experts can guide you on what’s best for you.
