Normet Self-Drilling Dynamic Bolts (SDDB®)
Overview
SDDB consists of a hollow, deformable bolt with an R32 ISO thread at both ends and a smooth, loose central part. The threaded parts have variations and can be used as anchor points, fasteners for self-drilling drills, couplings and plate/nut assemblies or for bonding broken parts. The smooth parts allow it to deform without restraint and absorb expansion energy by exploiting the plastic deformation properties of SDDB's patented steel.
It is installed in conjunction with pumpable resin or grout and can be used in two installation methods: as a single-stage, self-drilling system or as a two-stage installation in a pre-drilled hole. In large-scale applications, multiple segments can be interconnected to meet specific ground support needs.
SDDB provides rigid support initially, but is able to withstand significant deformation without failing, making it ideal for areas where rock movement or seismicity may occur, and allows for self-drilling.
Key specification
- Hollow, deformable bolt with an R32 ISO thread at both ends and a smooth de-bonded center section
Key benefits
SDDB®
- Can be installed into support holes prone to collapse or closing.
- Consolidates primary and secondary support into one installation
- Versatile configurations
- Single length or coupled extension
- Suitable to high-pressure injection
- Can act as a deformable injection lance for strata consolidation and reinforcement
- May be considered as an alternative to cable bolting in certain applications
Typical applications
- Deep mines with high in-situ stresses
- Operations seeking rapid installation of ground support
- Squeezing ground, broken, fractured, and fissured rock where typical bolts are difficult to install
- Problematic underground areas affected by stress redistribution or abutment
- Seismically active fault zones
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