Mechanical Expansion Bolt is a combined ground support system that uses a mechanical expansion anchor head for immediate point anchorage, and then forms full-length reinforcement through post-grouting.
A Mechanical Expansion Bolt is designed to provide fast initial support immediately after installation. The expansion anchor head is activated by tightening the nut, allowing the bolt to grip the borehole wall and carry load without waiting for grout curing.
Forms immediate mechanical anchorage inside the borehole.
Transfers load and provides the main support capacity.
Protects the bolt body and creates a channel for grouting.
Allows post-grouting after initial support is completed.
Explore our technical solutions for your tunneling or mining project
Learn More About Bolt SystemTraditional grouted rock bolts face critical challenges including long curing times and poor early-stage stability. Here are the main issues our mechanical expansion bolts are engineered to solve.
Traditional grouted bolts require hours or days to reach design strength before they can provide effective support.
Significant delays in the excavation cycle and prolonged exposure of unsupported ground.
Weak surrounding rock undergoes rapid initial deformation before the passive grouting system can engage.
Irreversible rock mass loosening and increased risk of collapse during the critical first 24 hours.
In fractured zones, the rock surface tends to flake off because the bolt doesn't apply an active "squeeze" force.
Requirement for excessive secondary mesh or shotcrete, driving up project costs.
The complex process of drilling, mixing grout, pumping, and cleaning equipment is labor-intensive and messy.
Slower tunneling progress and higher labor overhead in hazardous environments.
Experiencing project delays due to curing times?
Request Technical SpecificationDiscover the transformative engineering benefits of mechanical expansion bolts, designed to provide instant load-bearing capacity and active pre-tension control for complex projects.
Provides instant anchorage through mechanical expansion upon installation, allowing the bolt to carry its full design load immediately.
Enables the application of a high pre-tensioning force to the rock face via the torqueing of the nut, actively compressing rock layers together.
Combines early-stage mechanical anchorage with later-stage optional grouting (hollow bar versions) for permanent corrosion protection and full-length bonding.
A dry, mechanical installation process that requires minimal specialized equipment compared to resin or cement grouting systems.
Looking to optimize your engineering support strategy?
Talk to an Application EngineerOur mechanical expansion bolts utilize a sophisticated dual-phase reinforcement mechanism designed to provide instant stability while ensuring permanent structural integrity through advanced grouting technology.
Upon installation, the mechanical expansion head is activated, creating an instantaneous high-strength friction grip against the borehole wall. This provides immediate load-bearing capacity and prevents initial rock mass deformation or slippage.
The secondary phase involves pressure-injecting grout through the hollow bolt body. The grout fills the annulus and surrounding rock fractures, bonding the entire bolt length to the strata for permanent, corrosion-resistant reinforcement.
Precise borehole created to design depth.
Bolt inserted with expansion head at base.
Torque applied to lock mechanical anchor.
Immediate active support force applied.
Final cavity filling for total security.
By combining the speed of mechanical anchoring with the durability of grouted reinforcement, our systems reduce tunnel downtime by up to 30%. Consult an engineer today.
Download Technical SpecsExplore our comprehensive range of high-performance anchoring solutions engineered for diverse geotechnical challenges.
Standard Industrial Anchor
A versatile, high-strength steel bolt designed for general construction and basic geotechnical support.
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Heavy Duty Infrastructure
Enhanced diameter and torque capacity for heavy infrastructure and critical mining support zones.
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Soft-Ground/TBM Face
Fiberglass composite allows for safe cutting by TBM cutter heads during tunnel face stabilization.
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Marine & Acidic Environments
Galvanized or epoxy-coated options for harsh environments where chemical exposure is expected.
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Civil Engineering Optimized
Specifically designed for metro and highway tunnel linings with optimized expansion heads.
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Project-Specific Engineering
Bespoke lengths, material compositions, and thread patterns for unique geotechnical challenges.
View DetailsNot sure which Mechanical Expansion Bolt fits your project? Request a free geological analysis and selection guide.
Request Selection GuideExplore the critical components that make up our mechanical expansion bolt system, engineered for maximum grip, durability, and load transfer.
The core mechanism that provides immediate grip by expanding against the borehole wall upon rotation.
High-strength steel or GFRP core that transmits the load from the surface to the deep rock mass.
Protective outer layer ensuring long-term durability in acidic or alkaline underground environments.
Enables secondary grouting to fill the annulus, providing permanent full-length bonding.
The external assembly that applies active pre-tensioning force to the rock face.
One Integrated System for Immediate Support and Long-Term Reinforcement.
Request System DetailsReview the detailed technical parameters and performance metrics of our mechanical expansion bolts to select the optimal solution for your site.
| Parameter | CT-M20 (Steel) | CT-M22 (Steel) | GFRP Cuttable |
|---|---|---|---|
| Core Diameter (mm) | 20.0 | 22.0 | 20.0 - 25.0 |
| Max Tensile Load (kN) | 190 | 230 | Up to 300 |
| Expansion Range (mm) | 32-35 | 35-38 | 32-42 |
| Torque Requirement (N.m) | 250-300 | 300-350 | 150-200 |
| Application Type | Standard Support | Heavy Rockfall | Coal Face / TBM |
How to Choose the Right Mechanical Expansion Bolt Model? Our technical engineers can provide a site-specific recommendation based on your rock mass rating and excavation method.
Download Full Spec SheetEngineered for immediate stability in mining and tunneling projects, our steel expansion bolts provide reliable mechanical anchoring even in demanding rock conditions.
The expansion head provides instant grip upon installation, requiring no curing time for resin or grout.
High-tensile steel construction ensures maximum security in fractured rock mass and heavy-ground conditions.
Hollow core design allows for optional cement grouting after initial anchorage to prevent long-term corrosion.
Available in lengths from 1.5m to 6m with various galvanization options for different environmental classes.
When to Choose Steel Mechanical Expansion Bolt? Ideal for hard rock tunneling where instant load-bearing is required and the geological environment is stable enough to permit mechanical gripping.
Get Technical SpecificationsSpecifically designed for Soft Eye and TBM launch/reception areas, combining mechanical expansion speed with easy excavation.
A Glass Fiber Reinforced Polymer (GFRP) bolt equipped with a specialized mechanical expansion head. It provides the quick installation of a traditional bolt with the added benefit of being non-metallic.
Traditional steel bolts damage TBM cutterheads and conveyor systems. Our GFRP bolts can be easily cut into small pieces by the machine, eliminating downtime and protecting expensive equipment.
Active Site Application
Safe TBM excavation through reinforced ground
Material properties allow the TBM to bore through the support without sparks or tool damage.
The mechanical head anchors immediately, ensuring workers' safety during temporary face support.
Optimized for resin or cement injection to create a high-strength composite support system.
Reliable expansion in softer rock or urban tunneling where soil conditions are unpredictable.
When to Choose GFRP Cuttable Expansion Bolt? Choose this solution for TBM launch shafts, reception chambers, or any zone where support must be removed during the subsequent excavation phase.
Request GFRP Product GuideMechanical Expansion Bolt uses a two-stage support process: immediate mechanical anchorage after installation, followed by post-grouting reinforcement for long-term ground stability.
Prepare the borehole according to the required bolt type, diameter, and design depth.
Insert the pre-assembled Mechanical Expansion Bolt into the drilled borehole until it reaches the designed position.
Tighten the anchor nut with a torque wrench to activate the expansion anchor head.
Once the expansion anchor head grips the borehole wall, the bolt immediately provide initial support.
Inject grout to fill the space around the bolt and create full-length reinforcement.
Borehole diameter must match the bolt type to ensure proper expansion anchorage and grouting performance.
Correct tightening torque is required to activate the expansion anchor head and create reliable initial anchorage.
The plate should be pressed firmly against the rock or excavation surface to transfer support force effectively.
Post-grouting should fully fill the space around the bolt to form long-term full-length reinforcement.
Get a standard installation guide for your mining or tunneling project.
Get Technical SupportMechanical Expansion Bolt can be designed with polyethylene sleeve protection, grout encapsulation, and different steel surface treatments.
The steel body can be supplied with different surface protection options according to the corrosion level.
The polyethylene sleeve wraps around the bolt body and provides an additional protection layer.
After post-grouting, the grout fills the space around the bolt and creates a protective encapsulation layer.
Choose the right corrosion protection level for your engineering project.
Consult Corrosion SpecialistInstallation Torque, Grouting Fullness, Load-Bearing Performance, and Factory Inspection.
Precision calibration of tightening forces to ensure optimal expansion sleeve grip and initial rock tension.
Verification of chemical or cementitious grout flow to eliminate air pockets and ensure full-length anchoring.
Rigorous pull-out tests and axial load capacity validation matching specific geological conditions.
Automated 100% factory inspection of thread integrity and material hardness for every manufacturing batch.
Raw Material Analysis
Dimensional Verification
Mechanical Property Test
Corrosion Resistance Lab
Final Site Pull-out Test
'Quality Control Directly Affects Ground Support Reliability'
Download Compliance ReportProviding specialized support solutions for Tunnel, TBM Projects, Mining, and Infrastructure.
'One Bolt System for Multiple Ground Support Conditions'
Consult Project SolutionConnect with our engineering team for tailored support systems, factory-direct pricing, and technical consultation for your upcoming tunneling or mining project.
Eliminate middleman costs with direct-from-source pricing and strict quality control.
Tailored bolt lengths, diameters, and surface coatings specifically designed for your unique site.
Specialized heavy-duty expansion systems optimized for instant rock reinforcement.
Connect directly with our engineering team to get custom-designed solutions that minimize downtime and cut procurement costs.
