DYWI® Drill Hollow Bar
The DYWIDAG DYWI® Drill Hollow Bar System is a self-drilling soil nail solution designed to enhance ground stability across diverse geotechnical applications allowing for simultaneous drilling and grouting, and eliminating the need for casing in unstable or loose soil conditions.
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DYWI® Drill Hollow Bar System - Technical specification
DYWI Drill Hollow Bar with Couplers and Anchorages - Approval Z-14.4-674
DYWIDAG Soil Nailing System with Hollow Bars Type R32N - Approval Z-34.13-208
DYWI® Drill Hollow Bar System - Product guide - Brazil
Trusted worldwide. Proven onsite.
DYWI® Drill Hollow Bar is a fully threaded, self-drilling solution for ground engineering applications, including soil nailing, slope stabilization, micropiling, and rock bolting. Its design allows for simultaneous drilling and grouting, eliminating the need for casing in weak or collapsing soils.
Manufactured to the highest standards and compliant with European regulations, DYWI® Drill Hollow Bar ensures reliable performance in critical geotechnical projects. Its efficient installation process reduces on-site time and minimizes disruption, making it ideal for restricted access areas and sensitive environments.
Beyond its versatility, DYWI® Drill Hollow Bar enhances structural stability by reinforcing unstable ground and effectively transferring loads. Whether stabilising slopes, securing retaining walls, or strengthening foundations, it delivers durable and long-lasting reinforcement.
Key features
Simultaneous Drilling and Grouting
Designed to enable concurrent drilling and grouting, streamlining installation and reducing project timelines.
Versatile Threading Options
Available in various diameters, the system offers rope threads (R25-R51) and trapezoidal threads (T76), providing flexibility and stability.
Comprehensive Drill Bit Selection
A wide range of drill bits, including tungsten carbide options, ensures adaptability to various soil and rock conditions.
Global Standards Compliance
Manufactured from high-grade steel tubing in accordance with EN 10083-1, meeting international quality standards and ensuring reliability worldwide.
Combine with mesh for complete sytems
For enhanced surface stabilization, DYWI® Drill Hollow Bars can be combined with our high-performance mesh to create reliable surface support solutions. Whether your project requires active or passive stabilization, this combination offers enhanced structural coverage, improved load transfer, and durable long-term performance.
Used together, they form a complete ground support system—engineered for challenging conditions across diverse applications.
Versatile ground support solutions
Slope stabilization
Reinforces natural or engineered slopes to prevent landslides, erosion, or settlement—especially in areas with loose or weathered soils.
Soil nailing
Creates in-situ reinforcement for retaining structures and excavation faces, delivering stability through friction and load transfer.
Excavation Support
Secures vertical cuts and trench walls during construction, allowing safe access and reduced risk of ground movement or collapse.
Rock Bolting
Provides anchorage in fractured or unstable rock masses, commonly used in tunnelling, mining, and cut slope stabilization.
Foundations and Underpinning
Enhances load-bearing capacity and provides additional support for new or existing foundations, particularly in weak or variable soils.
Micropiling
Forms small-diameter piles ideal for confined spaces, low headroom, or where minimal vibration and ground disturbance are critical.
Tunnel Face Support
Stabilizes tunnel headings during excavation by securing the face and surrounding ground, helping to maintain advance rates safely.
Temporary or Permanent Retaining Structures
Offers structural reinforcement for both short-term excavation walls and long-term retaining solutions in infrastructure or building projects.
Technical specifications
DYWI® Drill Hollow Bar is engineered for reliability in demanding geotechnical environments. Its fully threaded design, high-strength steel composition, and through-bar grouting capability make it a versatile choice for a wide range of applications.
Thread Profiles & Bar Sizes - Available with rope thread (R25–R51) and trapezoidal thread (T76 and above) to suit varying ground conditions and project requirements. Additional sizes and custom configurations are available upon request.
Steel Grade & Material Compliance - Manufactured from high-grade steel tubing in accordance with EN 10083-1, ensuring consistent mechanical properties and global standards compliance.
Load Capacity & Design Life - Covers a broad range of tensile and compressive load requirements. Systems can be configured for temporary or permanent installations with adaptable design life expectations based on environmental exposure and corrosion protection level.
Grouting & Installation - The hollow core allows for efficient grout injection during drilling, saving time and reducing equipment needs. Compatible with rotary percussion, rotary drilling, and top hammer rigs. Injection adapters and sleeves are available for most equipment types.
Accessories - Includes couplers, nuts, bearing plates, injection adapters, and drill bit sleeves—ensuring a complete and flexible system.
Standards & Testing - All components are tested to meet EN, ASTM, and regional standards. Full technical documentation and test data are available upon request.
Corrosion protection options
DYWI® Drill Hollow Bars are designed to perform in a wide range of environmental conditions—from dry inland soils to aggressive marine or chemically contaminated ground. To support both temporary and permanent applications, we offer flexible corrosion protection solutions tailored to project needs and service life expectations.
01 Hot-Dip Galvanizing (HDG) - A cost-effective solution for general corrosion protection. The zinc coating forms a barrier that resists atmospheric corrosion and sacrificially protects exposed steel if damaged.
02 Epoxy Coating - Applied as a thick, durable layer, epoxy coating offers excellent protection against moisture, chemicals, and chloride intrusion—making it ideal for aggressive or marine environments.
03 Double Corrosion Protection (DCP) - A combination of galvanizing or epoxy with a corrugated plastic sheath and additional grout encapsulation. This is the highest level of protection and recommended for permanent applications or when installed in groundwater or high-risk areas.
04 Grout Encapsulation - In many cases, DYWI® Drill Hollow Bars are installed with pressure-injected grout, creating an additional protective barrier that enhances durability and long-term performance.
Not sure what protection level your project needs? Our technical team can help you select the right system based on soil chemistry, exposure class, and design life.
Accessories & system components
Rotary injection adapter
Connects the hammer to the hollow bar, allowing simultaneous drilling and grout injection.
Drill bit adaptor sleeves
Enables the use of larger diameter drill bits with smaller bar sizes for challenging conditions.
Drill tooling
Includes reducing couplers, box/pin adaptors, and spanners to support different rig types.
Sacrificial corrosion allowance
Extra steel thickness designed to gradually degrade over time in aggressive environments.
Bearing plates
Available with angle compensation or shear tubes for effective load distribution on uneven ground.
Beveled washers
Used with bearing plates on irregular ground surfaces to ensure secure seating.
Domed nuts, hex nuts, couplers, spacers
Secure and align threaded bars with flexible assembly options.
Non-return valves
Prevent grout washout in high water table areas—ideal for micropile installation without dewatering.
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