MEGABolt Water Expandable Rock Bolts (ERB)

MEGABolt Water Expandable Rock Bolt (ERB)

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The MEGABolt Water Expandable Rock Bolts range features friction bolts with superior product characteristics to meet the most demanding roof support applications. The high-load bearing capacity and excellent elongation properties ensure safer working conditions and faster excavation cycles for low costs.

Reinforcement with Water Expandable Rock Bolts occur by hydroforming (i.e., expanding) the bolt with high-pressure water against a drill hole wall. Water Expandable Rock Bolts expand into the hole shape when water at high pressure is pumped. The bolt expands to create a friction and interlocking anchor. MEGA Bolt’s ERB provides immediate full load-bearing capacity with safe and easy installation. Installation is easy and flexible to fit various drill hole diameters.

The MEGABolt Friction rock bolks are manufactured according to the ISO 9002 standards. Each batch and finished rock bolts are texted to ensure final quality.

The MEGABolt Friction Range consists of three products that provide 30% elongation:

Description of Expandable Rock Bolts

Rock surrounding underground excavations needs to be reinforced and stabilized in order to provide a stable and safe working environment. The ERB – Expandable Rock Bolt is a full column anchored rock bolt that forms a mechanical interlock between the borehole wall and the bolt over the full bolt length. This is achieved by inflating the ERB by means of high water pressure. When the pump stops the ERB immediately provides full rock support action. Also, when the Expandable Rock Bolts is inflated, it causes a contraction in the bolt length, which effectively tensions the face plate against the rock surface.

Applications of Expandable Rock Bolts

The Expandable Rock Bolts is a cost-effective means of rock reinforcement in a variety of rock conditions from soft to hard rock. It is flexible and will allow variations in the borehole diameter. The ERB is designed to accommodate large rock movements and still maintain its high load bearing capacity. Further the ERB is an environmentally friendly rock reinforcement solution with no cement grout or other chemicals required to anchor the bolt. The ERB may be installed manually or fully mechanist -just add water. The main applications of Expandable Rock Bolts are:

Advantages of Expandable Rock Bolts

Technological Features of Expandable Rock Bolts

The MEGABolt Expandable Rock Bolts range features friction bolts with superior product characteristics tomeet the most demanding roof support applications. The high load bearing capacity combined with excellent elongation properties ensure safer working conditions and faster excavation cycles for low costs. Reinforcement with ERB occurs by hydroforming (i.e. expanding) the bolt with high pressure water against a drill hole wall. ERBs expand into the shape of the hole when water at high pressure is pumped. The bolt expands to create a friction and interlocking anchor. MEGABolt’s Expandable Rock Bolts provide immediate full load bearing capacity with safe and easy installation. Installation is easy and flexible to fit various drill hole diameters. MEGABolt ERB consists of folded steel tube with upper bushing and inflation bushing welded at each end of the tube. A specially designed adjustable face plate is delivered as an option. ERB requires steel with extremely good elongation and formability properties. This produces a finished bolt that will be able to accommodate large rock movements and still maintain its high load bearing capacity. The MEGABolt ERB delivers a high level of safety and uninterrupted production in the customer’s operations. High quality steel guarantees homogenous material for MEGABOLT ERB, Expandable rock bolts. Expandable rock bolts are manufactured from unique steel in the Nordics. Each production stage from steel manufacturing to profiling and assembling of rock bolts belongs to partners own production and quality control chain. Quality control secures that the product is regularly tested to guarantee quality and safety. Each individual ERB is marked with a unique code, which enables full traceability of the bolts.

Technical Specifications of Expandable Rock Bolts

MEGABolt guarantees a minimum breaking load as well as corresponding elongation for all ERB. MEGABolt Expandable Rock Bolts are available in two types,

Each type includes bolts with three different load bearing capacities:

The difference between the MEGABolt Expandable Rock Bolts and MEGABolt ERB+ is the elongation characteristics: the cold formed type, the MEGABolt ERB has an elongation A5 ~ 15% and the cold formed and normalized type the MEGABolt ERB+ has an elongation of A5 ~ 30 %.

With MEGABolt ERB+, MEGABolt is the leading manufacturer of expandable rock bolts. The MEGABolt ERB+ is made of special steel which go through a specially developed annealing process which give the bolts their exceptional elongation characteristics and still maintain the high load bearing capacity. This gives the MEGABolt ERB+ superior properties in order to accommodate large rock deformation in high deformability rock masses, e.g. squeezing rock.

	ERB 120 ERB 120+		ERB 160 ERB 160+		ERB 240 ERB 240+
Bolt Diameter	28 mm		28 mm		38 mm
Profile Diameter	27.5 mm		36 mm		36 mm
Material thickness	2 mm		2 mm		3 mm
Upper Brushing Diameter	28 mm		38 mm		38 mm
Inflation Bushing diameter	30/37 mm		41/48 mm		41/48 mm
Hole Diameter	32-39 mm		43-52 mm		43-52 mm
Minimum Breaking Load	120 kN		160 kN		240 kN 230 kN
Minimum Elongation	10%	20%	10%	20%	10%	20%
Typical Elongation	15%	30%	15%	30%	15%	30%
Standard Lengths	1.5 - 4.0 m		2.4-6.0 m		2.4-6.0 m

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