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11 months ago

Design of the Unbonded Length

Design of the Unbonded Length

The minimum unbonded length for rock and soil ground anchors is 4.5 m for strand tendons and 3 m for bar tendons. These minimum values are intended to prevent significant reductions in load resulting from seating losses during transfer of load to the structure following anchor load testing.

Longer unbonded lengths may be required to:

(1) locate the bond length a minimum distance behind the critical potential failure surface;

(2) locate the anchor bond zone in appropriate ground for anchoring;

(3) ensure overall stability of the anchored system; 

(4) accommodate long term movements.

In general, the unbonded length is extended a minimum distance of H/5 or 1.5 m behind the critical potential failure surface (see section 5.3.2) to accommodate minor load transfer to the grout column above the top of the anchor bond zone.

As a general rule, the anchor bond zone and unbonded zone should be grouted in one stage to maintain hole stability and to create a continuous grout cover for corrosion protection.

However, for large diameter anchors in which the unbonded length of the anchor extends just behind the critical potential failure surface, significant strains at the top of the anchor bond zone may cause load transfer into the grout column above the anchor bond zone.

Large diameter anchors have been grouted in two stages (two stage grouting). With two stage grouting, the anchor bond length is grouted (Stage 1) and the anchor is tested. The unbonded length portion of the drill hole is then grouted (Stage 2) after the anchor is tested.

The two-stage procedure is not recommended since local collapse of the ground can occur which will compromise the corrosion protection provided by the grout.

From:https://www.fhwa.dot.gov/engineering/geotech/pubs/if99015.pdf

11 months ago

Where to find high strength bolts

Where to find high strength bolts

Metis is a professional manufacturer and supplier of rock anchors as well as high strength bolt system,which located in Luoyang,China,a city with thousand years of history and glorious culture.Metis own two plants,one is sited in Luoyang,the other is in Changzhou,Suzhou province in China,Changzhou plant is near Shanghai,which is the largest as well as the most developed city in China,with convenient transportation and easy collection of raw material.

Metis specialty rock bolts have been exported to more than twenty countries,clients are all speak highly on our featured products like self-drilling bolts,fiberglass rock bolts,large-diameter anchor bar,stainless rock anchors and epoxy anchors.

Metis dill anchor has been widely adopted in complicated loose and broken geological condition,as well as pre-support project,radial support project,slope stabilization,foundation support project,soil nail wall,back pull anchor rod retaining wall and couples of other civil reinforcement works.

What's more,Metis mechanical bolt can be tailored by our global clients,these anchoring products will be cut and connected at any point depending on the specific desire of our customers,so there is no need to worry about the size,it can be customized by you and whatever your post anchor requirements may be we can produce specials on request.

CALL us to discuss your particular desire.

11 months ago

Abundant design principlesfor engineers referring to R32

Abundant design principlesfor engineers referring to R32

A number of remedial methods can be implemented in thecase of existing buildings, in order to improve their mechanica lcharacteristics. Among the various methods available, the use ofanchor systems is one of the most effective ones.Anchor systems are commonly used in plain or reinforced concrete, as well as for structurally strengthening and retrofittingexisting constructions and for connecting new structural elementsto existing ones. 

Using post-installed anchor systems is a very efficient connection technique for structural reconstruction and expansion, and there have been a large number of studies on the behavior of adhesive anchors. Cook studied the data base including 888 European and American tests and developed a better and more user-friendly design model than those existing previously. 

An achitect proposed a new failure mode and verified its validity using a worldwide database containing 415 tests.Further, Eligehausen has reviewed the development of adhesive anchors in the United States. Finally, abundant design principlesfor engineers referring to R32.

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12 months ago

T127 self drilling hollow anchor bolt is a type of large diameter anchor bolt

T127 self drilling hollow anchor bolt is a type of large diameter anchor bolt

T127 self drilling anchor bolt system is composed of the anchor bar, anchor coupling, anchor nut, anchor plate and drill bit. This system is made of seamless steel pipe with thick wall. In addition, surface thread-shaping technology is taken.

T127 self drilling anchor bolt system eliminates the requirement for a cased borehole. Therefore, it has a high rate of installation since drilling, placing and grouting can be performed in one single operation.

 

Features

1. Easy to penetrate various rocks.
2. It can be elongated by using couplers.
3. Unnecessary to be pulled out.
4. The hollow bar can be used as grouting channel.
5. Drilling, grouting and anchoring can be finished at the same time.

 

Application

•Weathered rock
•Gravel layer
•Backfill
•Hard conglomerate
•Gravel layer

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12 months ago

Why choose Metis Self-drilling hollow anchor bar?

Why choose Metis Self-drilling hollow anchor bar?

Metis has achieved the certification of ISO quality control system(provided by BV company) , the whole self-drilling anchoring system has pass the CE certification since 2011.

Our target is to produce first-class anchoring products to service high-end customers globally.  Our mission is provide one-stop solution service for clients all over the world.  During the production, the workers need to do the first article inspection by themselves and the inspector will do random test for products, all of the inspection data will be recorded. 

Our company has its own lab, equipped with tensile testing machine and other testing machines, each batch of goods is provided with the test report from our lab, we can also provide test report issued by third party test organization if needs, such as SGS test report.

And we set up different departments and sections in charge of different business, which include Marketing Center, Sales Center, Technical Center, Luoyang Factory, Changzhou Factory, QC Center, Planning & Management Department, Financial Department, HR Department and Administrative Department. 

If you have any question please contact me asap,we have professional service team here to provide drilling solutions for you,you are welcome to visit our company as well as plants.

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1 year ago

Metis is committed to the goal of sustainable development

 Metis is committed to the goal of sustainable development

The self drilling anchor systems range includes self drilling anchor system,self drilling anchor bolt,self drilling rock bolt,self drilling hollow anchor,self drilling anchor and so on.

Metis is committed to the goal of sustainable development and research of anchoring products. We balance social, environmental and economic considerations in how we manage our business. 

We believe that operating to leading standards of health, safety and environmental management and engaging with our stakeholders in two-way, open dialogue enhances our business reputation and is a source of competitive advantage.

We comply in full with the laws and regulations governing our business and conduct regular internal and external audits of our businesses and operations to assure compliance with our business principles, policies and standards.

We aim to construct a safe workplace that is injury free, and to enhance the well-being of employees, sub contractors and visitors.

We provide visible safety leadership, and appropriate leadership development and training at every level;

We engage and maintain a positive safety culture, behavior, and awareness;

We provide safe work systems and occupational health and hygiene programs;

We report, manage and learn from injuries, illnesses and high potential incidents.

If you have any question please don't feel any hesitate to contact us at any time,we have professional service team to provide perfect drilling solutions and anchoring measures,we warmly welcome all the groups to communicate and visit,here are experienced team waiting for you!

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1 year ago

Forepoling of Metis self drilling anchor

Forepoling of Metis self drilling anchor

In order to prevent the deformation and loose of the rocks caused by the application of mining,tunneling,foundation support,hydroelectric project and other civil constructions,forepoling of rock bolt can play a significant role in giving a perfect effect and offering best anchoring solutions.

Excavation and install the self drilling anchor into the rock surface should be processed at the same time,under the protection of temporary loading structure of the stratum,forepoling is well suited to the excavation of soils and rocks.Press concrete or prepare some tendons within the steel pipe to guarantee the grout can be filled sucessfully.

Rock bolt of Metis self drilling anchor can be applied in a great many ground conditions,such as broken rocks,loose soils,low-buried tunnel and fracture zone.In general,the thickness of steel pipe is 10-30mm and the diameter of anchor bar is 80-180mm.

If you have any question please don't feel any hesitate to contact us at any time,we have professional research&development group here to provide drilling service and reliable and practical placing solutions for you!

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1 year ago

Forepoling of Metis self drilling anchor

Forepoling of Metis self drilling anchor

In order to prevent the deformation and loose of the rocks caused by the application of mining,tunneling,foundation support,hydroelectric project and other civil constructions,forepoling of rock bolt can play a significant role in giving a perfect effect and offering best anchoring solutions.

Excavation and install the self drilling anchor into the rock surface should be processed at the same time,under the protection of temporary loading structure of the stratum,forepoling is well suited to the excavation of soils and rocks.Press concrete or prepare some tendons within the steel pipe to guarantee the grout can be filled sucessfully.

Rock bolt of Metis self drilling anchor can be applied in a great many ground conditions,such as broken rocks,loose soils,low-buried tunnel and fracture zone.In general,the thickness of steel pipe is 10-30mm and the diameter of anchor bar is 80-180mm.

If you have any question please don't feel any hesitate to contact us at any time,we have professional research&development group here to provide drilling service and reliable and practical placing solutions for you!

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1 year ago

Quality control process and accessment of Metis self drilling anchor bolt

Our quality control process contains raw material incoming inspection, Production process inspection, Finished products inspection,outgoing products inspection and solve Customer complaints. 

Inspection data should be recored. Unqualified products can't flow into next working procedure. Data for unqualified products should be analyzed and improvement measures should be proposed. 

For Metis self drilling anchor bolt, the steel we commonly used for R25 is Q345. The Steel we commonly used for other sizes like R32/R38/R51/T30/T40/T76 is 40Cr which European name is 40Cr4. The steel we commonly used for coupler is  40Cr which European name is 40Cr4.

1.The steel we commonly used for forged nut is 45# which European name is ZK45. 
2.The steel we commonly used for casting nut is Q235 which European name is SJ235. 
3.The steel we commonly used for R25/R32/R38/R51/T76/T111 plate is Q235 which European name is SJ235.
4.The steel we commonly used for T30/T40/T52/T73/T103/T127/T130 plate is 45# which European name is ZK45. 
5.The steel we commonly used for casting drill bit is 42CrMo. 
6.The steel we commonly used for tungsten carbide drill bit is 40Cr. 
7.The steel we commonly used for centralizer is QT500. 

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1 year ago

The passivation process of Metis self drilling anchor bar

The passivation process of Metis self drilling anchor bar

During the period of 10 months of partial immersion of samples in the NaCl solution, the potential still continues to be at low performance considering the corrosion, according to ASTM C876, which may imply passivation of the self drilling anchor bar, although the above notice alone cannot be considered as decisive evidence of the passive state of the hollow steel bar.

It is important to highlight that the potential oscillation is result from drying/immersion cycles, in aother words, in speaking of concrete humidity.
When the self drilling anchor bar surface is humidified, a decrease in the resistivity happens, improving the current flow and changing the potential values.

The consequences obtained by OPC were indentified in the EIS, by Nyquist and Bode diagrams. The Nyquist complex plane graph is a plot of the resistive Zreal against the capacitive Zimag, while Bode diagrams are plots of the logarithm of the impedance modulus Z and phase angle against the logarithm of frequency.

If you have any question please don't feel any hesitate to contact us at any time,we have professional service team waiting for you!

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