Historic Building Renovation Using Hollow Bar Micropiles
We recently helped a contractor install a new concrete foundation while preserving the exterior of a historic building. Learn more about the problems encountered and the solution we provided.
What Was the Problem?
A local building required new concrete foundations, but the brick exterior needed to be preserved. The building holds historical significance, and protecting the exterior was a top priority. The contractor reached out to Intech for help with installing the new foundation.
What Solution Was Selected?
Intech decided to use Magnacore T76 hollow bar self-drilling anchors to support the new concrete foundation. This solution was chosen because the structural load was high, and the varying soil conditions required a significant rock socket.
Were Any Challenges Encountered?
The contractor had never installed a hollow bar before. The rock socket was more challenging than anticipated, which led to more grout being used. The lack of access to the interior of the structure forced the contractor to be flexible.
How Did Intech Assist with the Project?
Intech provided the materials and installation equipment, assisted with the design of the anchors, and helped train the installers.
What Was the Outcome of the Project?
Intech helped the contractor overcome the challenges and complete the project on time. The contractor appreciated our assistance, and is now more comfortable working with hollow bar solutions
Self-Drilling Anchors FAQ
What Are Self-Drilling Anchors?
A helical pile is a foundation system that consists of round steel shafts attached with helical bearing plates. Helical piles are an ideal and cost-effective solution for stabilizing foundations and increasing load capacity.
A self-drilling anchor is a hollow bar injection-bore micropile that serves as a solution for challenging soil conditions. Self-drilling anchors are ideal for situations where installing traditional micropiles may not be the best option. Soils that are collapsible or contain large boulders may require self-drilling anchors.
What Are the Benefits of Self-Drilling Anchors?
The hollow bar design allows self-drilling anchors to work in nearly every type of soil. The system allows the steel bar to be drilled and grouted into loose or collapsing ground. Self-drilling anchors are easy to use and ideal for working in urban areas because they make little noise.
How Are Self-Drilling Anchors Installed?
Hollow bars inject grout while drilling and use sacrificial bits that remain in the ground after installation. The bits are used as a stabilizer, and they limit material costs by serving two functions. Once injected, the grout permeates into the looser adjacent soils, forming a reinforced grout column.
What Types of Sacrificial Bits Are Used?
Hollow bars inject grout while drilling and use sacrificial bits that remain in the ground after installation. The bits are used as a stabilizer, and they limit material costs by serving two functions. Once injected, the grout permeates into the looser adjacent soils, forming a reinforced grout column.
Self-drilling anchors use three types of sacrificial bits:
- Tungsten Carbide Button Bit: ideal for use on hard rock, such as limestone or shale
- Tungsten Carbide Cross Cut Bit: used on softer rock, including sandstone or fractured rock
- Clay Bit: used for mixed fills and clay
These bits are designed for single use and remain in place once they reach the correct depth.
What Are the Applications of Self-Drilling Anchors?
Self-drilling anchors are the most popular and cost-effective solution for any project based on difficult soil. They utilize skin friction to leverage maximum capacity, saving time and limiting labor costs. Some of the more common applications of self-drilling anchors include:
Slope Stabilization
Self-drilling anchors stabilize uneasy soil foundations.
Foundations with Micropiles
Self-drilling anchors are placed in sites with limited space using light drilling equipment, making them ideal for sites where micropiles have been installed.
Tunneling
Self-drilling anchors are the best solution for reinforcing the tunnel circumference in overburdened rock conditions.
What Is the Difference Between a Solid Bar and a Self-Drilling Anchor Hollow Bar?
Predrilling
A solid bar requires predrilling, while no predrilling is necessary for hollow bar anchors.
Soil Limitations
Solid bars are limited to shallow rock soil, while hollow bars are used at any soil depth.
Grouting
Using a solid bar requires the installer to grout before and after installation. A hollow bar actively grouts during the installation process.
For over 20 years, Intech has supplied contractors with innovative foundation solutions. We pride ourselves on our unmatched level of customer service. In addition to materials, we provide support throughout the entire project. Contact Intech today to see how we can solve your unique foundation problems.
