Using Hollow Bar Micropiles in Challenging Conditions

Though small in diameter, micropiles are incredibly strong. Designed to support loads in excess of 200 tons, they stabilize slopes, foundations, and structures at both shallow and deep depths. Because they can be installed in almost any subsurface, micropiles are one of the most popular and cost-effective support solutions. Installation is simple and rarely disrupts facility operations.

Advantages of Hollow Bar Systems – The Magnacore Self-Drilling Anchor (SDA)

Hollow bar micropiles are designed specifically for soils unfavorable to open-hole drilling. In these environments, conventional micropiles aren’t good options, as the looser adjacent soils are subject to movement and instability. To deal with unyielding ground conditions, hollow micropiles offer an ideal anchor system where cement grout mix is injected through the hollow bar. This subsequently doubles as the drill string.

Grounds where the hollow bar might be used include:

  • Collapsible soils – not conducive to traditional open-hole drilling
  • Areas with large boulders or obstructions
  • Areas with limited space, such as basements

Understanding the Hollow Bar Process

Hollow bar micropiles provide strength perfect for difficult terrain. They are formed through single top-down operations, during which a cement grout mixture is injected with high-pressure through the center of the hollow bar micropile. This center also acts as the drill string. When the grout protrudes through the opposite end, it anchors itself to the surrounding adjacent soils, solidifying into a reinforced grout column that provides incredible strength and boosts structural integrity.

Applications for Magnacore SDA Hollow Bar

Hollow bar micropiles are the most popular and cost-effective solutions for any project based in questionable soil. Magnacore SDA hollow bars create stable foundations for new construction projects, though they can reinforce existing structures as well. In these situations, the hollow bar micropiles work on skin friction to leverage maximum capacity, thereby saving time and labor costs. Furthermore, Magnacore SDA hollow bars enhance underpinning efforts by strengthening the foundation of loose soil. Even if a building rests on a sturdy foundation, the soil may have been mischaracterized and would need to be stabilized by supporting hollow bar micropiles.

Because they improve the properties of supporting soil and foundation, Magnacore SDA hollow bars may be used in earth retention projects – even in areas prone to earthquake, flood, drought, and similar landscape conditions. Slope stabilization and tunneling can also be accomplished through the application of hollow bar micropiles.

Benefits of the Magnacore SDA Hollow Bar

The sturdy cement grout makes the hollow bar micropile an excellent solution for challenging terrains. Furthermore, as drilling, installing steel, and injecting grout can be done simultaneously in a single operation, the hollow bar has a high installation rate that ensures worksite efficiency and is suitable for locations with limited access and confined workspaces. Moreover, the hot-dipped galvanizing offers protection from corrosion and harsh elements. With lower labor and materials cost, the SDA MAI Hollow Bar system is an efficient, flexible solution to project needs – even in the most challenging conditions.

The Hollow Bar Advantage

In comparison to solid bars, hollow bars provide greater benefits because they don’t require any pre-drilling and can work in all soil types. Casing for lateral loads ensures maximum strength while grouting can be done during installation.

Intech Anchoring is the industry leader in both piling repair and piling replacement services. Contact us today at 800-223-7015 to learn more about the SDA MAI Hollow Bar system.

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Tim Comb


Tim is the President of Intech Anchoring and has 25 years of experience in the Civil Engineering and Geostructural Industry. Tim has developed extensive industry knowledge by working to support the needs of specialty contractors at each and every business level. Tim’s diverse industry background has given him exposure to a wide variety civil construction projects, ranging from the simplest residential applications to the most complex commercial and industrial projects. Coupled with a highly skilled and educated team, Tim focuses on providing the highest quality products and solutions to Intech Anchoring’s customers in order to consistently exceed expectations.