Micropiles: What You Need to Know

Micropiles go by several names. They may be called needle piles, root piles, mini-piles, or pin piles. Regardless of what they’re called, they serve the same purpose. They are a high-performance and high-capacity deep foundation elements. A micropile foundation can be used to support a wide range of structure types.

Benefits of Using Micropile Foundations

Why should micropiles be considered? Quality micropile design can provide a wealth of benefits to those who choose this option. It allows for the creation of piles that have a high axial load capacity compared with other options. They are easy to install even in confined spaces, and there aren’t any vibrations that may harm surrounding structures.

Another one of the benefits of using micropiles is their versatility. Sometimes, builders may need to set up a foundation in an area that has unsuitable soil. With a deep micropile foundation, it’s possible to transfer the structural load through the layers of soil to reach better foundation soils. For example, they work well when there are obstructions in the ground, whether natural or manmade.

When compared with large diameter drilled shaft foundations, especially those on difficult ground, the micropiles are cost-effective. They are also durable and practical when compared with larger options. The piles are lightweight and compact, making them easy to install and can work for many locations and types of terrain. Despite being more compact, they are still strong and capable, making them a good solution for nearly any type of structure.

Common Applications for Micropiles

Micropiles are used for a range of purposes. They are often used for new foundations today because of the benefits they confer. Starting a new building with the “solid footing” that’s provided by quality micropile design can be a good way to ensure the structural integrity of the building from the start.

Micropiles are also used for retrofitting. Micropiles are uniquely suited to retrofits because they can be installed in limited access areas. Typical retrofits include building augmentation or seismic retrofitting. Most commonly, micropiles in retrofits are used to combat swelling soils or to install things like elevators in existing structures.

Seismic retrofitting is a type of retrofit that is used to modify existing structures and to make them more resistant to earthquakes. During a quake, there is motion in the ground, and the soil moves. If the foundations aren’t deep enough and strong enough, it can cause a host of problems with the building’s overall stability. Those who live in areas prone to earthquakes and who do not have a stable foundation—whether it’s for a home or business—may want to consider micropiles.

Micropiles can also be used for retaining wall earth retention, which may be important in areas that could be prone to landslides. The micropiles are useful for underpinning structures that already exist, and reinforcement for slope stabilization. Micropiles help transfer loads, provide better structural support, and improve mass stability for the structure. Those who have foundation systems that are deteriorating may find that a good and relatively easy way to replace the system is with micropiles.

Micropiles are often used when working in remote areas or on steep slopes. They work well in a basement, for overpasses, in wetlands, rocky areas, and even for river pier foundations. Because they can be installed at different angles, it makes them an even more flexible option.

Given all the benefits they offer and the multiple ways they can be used, it’s easy to see why micropiles are becoming one of the most common construction applications today.

Micropile Installation

The micropile installation process is relatively simple. First, a deep hole with a small diameter is drilled and then the steel element can be lowered into the hole. The diameter will usually be between three and twelve inches, but it will vary based on how and where the micropile is being used, as well as the load requirements. The depth of the hole will vary based on the ground conditions and the structure that’s being retrofitted or built.

Once the steel is set into the drill hole it is encased in concrete, this is what creates the strength of the pile. Unlike other larger diameter piers, the strength of a micropile comes entirely from the grout to soil bond or “side shear”. When a pile is put under load the concrete expands in all directions and creates a bond between the ground and the concrete, this is what allows the pile to resist building forces.

After it sets, support systems can be added to the top of the micropile. Having a quality support system helps to ensure that the weight is distributed evenly.

With the right micropile drilling rigs, it’s possible to allow for the installation of micropiles in nearly any location, including areas that have restricted access or only a small amount of headroom, GeoCraft can install piles with as little as 12’ of overhead clearance! This is especially helpful in the case of retrofitting. With these types of micropile drilling rigs, it could allow for the upgrade of a location without the need for massive disruptions to an operation.

Unique Micropile Design for Different Structures

All locations and structures are unique. Even though the basics behind micropile installation and drilling have similarities, there will be differences in the design to ensure it works for different locations and structures. Professionals know and understand how to work in different types of soil and how to use the micropiles for various purposes. Although the design may be similar to micropiles used by other buildings, each one should be approached as a unique property.

Choose a Professional Company for Your Micropile Foundation

Those who require a new foundation, retrofit, etc., will always want to work with a reputable professional that can design and install the micropile foundation. GeoCraft can design and install all types of micropiles and has the experience in different soil conditions to ensure quality. GeoCraft can even test the piles’ capacity after installation to ensure that the new foundation is capable of handling whatever is being thrown at it.

The owners of GeoCraft Builders, have over 40 years of combined experience and can provide the guidance needed for your specific needs. Learn more about our micropile installation services by contacting us today.