Using Micropiles
Micropiles are a deep foundation system that is grouted and reinforced typically less than 300mm in diameter. Micropiles are suitable for virtually all soil and rock conditions and can be used in many applications.
Micropile systems offer the following features and capabilities:
- EROSION CONTROL
- QUICK INSTALLATION
- HIGH LOAD CAPACITY
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When completed, these piles generally consist of a central steel reinforcement member and hardened grout that maintains a lasting bond between the micropile and the surrounding soil.
Micropiles typically achieve capacity through skin friction between the grout and soil or rock. When socketed into bedrock very high capacities can be achieved. Typical micropiles rely on boring a hole with the use of casing to maintain the hole, then placing grout and reinforcement in the hole. Hollow bar micropiles use the drill string as the reinforcing steel and are able to maintain the hole diameter by constantly pumping grout through the bar during installation. Micropiles are often a cost effective solution to more traditional approaches to ground improvement.
Micropile Foundations Vs. Drilled Pier Foundations
Unlike a drilled shaft pier, micropiles derive a large percentage of their load capacity from the steel reinforcement bar. This reinforcement, coupled with load absorption through skin friction, makes them excellent for both tension and compression loads. Steel casing can also be added to address lateral loading requirements.
With a typical drilled pier foundation, significant cost overruns can occur due to extra rock coring. Drilled piers are extended along the face of sloping rock or when voids are encountered in the rock formation near the design bearing elevation of the drilled piers, they can collapse, and extra rock coring is required.
Micropiles reduce this risk as they extend into the rock formation and rely on cement grout to fill gaps in the soil, creating an impermeable bond between the micropile and the surrounding soil. Loads are then absorbed by the skin friction between the micropile and the soil. As a result, potential voids and gaps in the soil foundation are automatically filled during installation.
Micropile System Applications
Micropiles can be used in a variety of applications such as vertical compression and tension elements, tiebacks, soil nails, retrofitting existing structures and more. They are particularly useful when projects are launched in areas with limited access or weak soil. This system has become a preferred method of deep foundation stabilization for its reliability, versatility, and efficiency. It’s also an optimal solution to remediate ground stability issues beneath existing structures or buildings.
Intech Anchoring Systems supports these products with our design expertise and fleet of rental equipment as needed. Before you can decide if they are the best option for your project, it’s vital to understand their applications.
For an overview of their components and practical uses, review this brief guide:
Micropile Deep Foundation Projects
Building a deep foundation is necessary for job sites of high capacity loads, on-site barriers, or poor soil. A micropile deep foundation project relies on groups of micropiles to deliver the exact load requirements for your application. Hollow bar micropiles are a convenient option for establishing a deep foundation because they frequently do not require pre-drilling or pre-/post-grouting, streamlining installation, and reducing project costs.
Micropile Foundation Rehabilitation & Repairs
When existing foundations are compromised, micropiling installation techniques can be adapted to operate to tight confines, including in existing buildings with limited overhead space. When other deep foundation options aren’t feasible to repair the foundation of an existing structure, micropiling offers an alternative that’s just as effective and often easier to budget. Ultimately, it’s one of the more cost-effective foundation repair options, particularly when compared to foundation replacement.
Micropile Foundation Stabilization Of Adjacent Structures
Micropiles can be used for projects with nearby structures or limited access. Since micropile installation equipment is smaller and less intrusive, it’s an ideal option for structures sharing adjacent walls that may interfere with the accessibility of your project.
Solid Bar Micropiles Vs. Hollow Bar Micropiles
Intech proudly supports Magnacore as our industry leading hollow bar micropile. Traditional solid bar micropiles require a hole being pre drilled, the reinforcement placed, and then post grouting after the fact. This is problematic in sandy or weak soil conditions because the hole may collapse prohibiting installation without the use of casing during installation. This condition arising in the field with a typical solid bar can cause construction delays. Hollow bar micropiles maintain grout in the hole during the entire installation and grout is pressurized during the advancement of bar allowing for grout permeation into sandy soils improving capacity. The grout filling the hole at all times eliminates this need for casing during installation. Casing can can be added to a hollow bar micropile to meet lateral load conditions but typically only needs to be advanced to 15 ft or less unlike traditional solid bar micropiles which may require this casing to the depth of bedrock.
Micropile Jobs & Considerations
Micropile deep foundation systems can be used on a variety of projects, including the fortification or creation of foundations for bridges, towers, and new buildings. Their versatility has led to their increased popularity and their use in complicated and challenging construction conditions. When faced with low-clearance areas, restricted access, or collapsing soil types, micropiles are an ideal solution.
When compared to other foundation products, micropiles are highly customizable and cost effective. They eliminate the need for additional steps during installation, including pre-drilling, pre-grouting, and post-grouting. As a result, project timelines stay on track, and quick installation reduces project costs, both in terms of materials and labor expenses.
Intech Anchoring Systems offers a range of cost-effective micropile solutions that are ideal for projects with limited functional access or low-headroom areas. Our micropiles are designed for quick and efficient installation, saving you time and money. To determine the most suitable micropile option for your next project, we invite you to contact us today. Our team of experts will provide personalized guidance and help you make informed decisions for a successful project.
