Self-Drilling Anchor Bolts
Self-Drilling Anchors are a bolting solution for unstable ground conditions such as sand, gravel, silt, and clays, and in soft to medium fractured rock formations.
For projects facing such ground conditions, self-drilling anchors should be considered as the main productivity solution. Self-Drilling Anchors from MDTI are designed for optimized installation, tailored to the project’s needs.
By drilling a hole in collapsing soil or loose rock, with a sacrificial drill bit and a hollow rod, and after the drilling operation injecting cementitious grout or resin into the hollow rod and surrounding cavity, self-drilling anchors are a top productivity solution.
Self-drilling anchors from MDTI consists of:
- A hexagonal nut
- A bearing plate
- Extension couplings, if the anchor consists of several anchor rod sections
- Hollow anchor rod(s)
- A sacrificial drill bit
Applications of Self-Drilling Anchors
Self-Drilling Anchors are used to stabilize unstable rock/soil formations. The unconsolidated or weathered ground conditions favor the SDA technique for a fast and simple method of installation compared to the traditional methods.
Foundations with micropiles
SDA micropiles can be defined as drilled piles, composed of injected grout with the anchor rod as steel reinforcement. They can be installed in sites with limited space using light drilling equipment, can be installed into most ground conditions including rock and are suitable for tension and compression loads. The big advantage is the combined drilling and grouting making high piling outputs possible.
Self drilling anchors are the most economical solution for the reinforcement of the tunnel circumference and advanced roof support for tunnel excavation in overburdened and soft fractured rock conditions.
Self-Drilling Anchor Equipment & Drill Bits
Sacrificial drill bits
The sacrificial drill bit is the most crucial part of the anchoring system and is responsible for the productivity of the installation. MDTI offers a large range of drill bits to suit the changing geology encountered during projects. In order to improve on performance and cost efficiency, data is collected from projects around the world and incorporated into the design with the goal to improve penetration rate and bit quality and to reduce manufacturing and application costs.
The selection of drill bits
A successful installation of the SDA system depends on the selection of the most suitable drill bit. Compared to conventional drill bit types offered globally for maximum standing performance for rock or soil, the criteria for SDA drill bits are defined by consideration of the following factors:
- High quality for a limited service life
- Installed MAI SDA length