T73 Self Drilling Anchor Bolt

T73 self-drilling threaded hollow bolt is a self-drilling bolt system composed of hollow steel bars, couplers, nuts, and steel backing plates. It can provide cost-effective anchoring solutions for unstable ground conditions and cracked rock formations. 

Product Description

1. The T73 self-propelled bolt can be connected with a grouting machine for grouting while drilling to achieve the anchoring effect. The construction efficiency is higher than that of ordinary hollow bolts, and it is suitable for broken and difficult-to-form surrounding rock.

2. There is no need for casing wall protection during construction, which can greatly improve the construction efficiency, shorten the construction period and reduce the overall cost of the project.

3. The hollow bolt body can be arbitrarily cut and lengthened by connecting sleeves. Therefore, the self-propelled bolt can also be constructed in the narrow space where large equipment cannot enter.

4. Compared with the conventional drill pipe, the T73 self-propelled bolts is equipped with a variety of drill bits, which can be selected according to the properties of different rock layers and soil during construction, which can improve the drilling efficiency.


Corrosion resistance

In engineering applications, the corrosion of the surrounding environment has the greatest impact on the service life of the self-propelled bolt, so the anti-corrosion design of the bolt is particularly important. In order to meet the needs of customers, JiuFu provides a variety of anti-corrosion T73 self-drilling anchor bolts, such as hot-dip galvanized anchors, epoxy coated anchors, double anti-corrosion anchors, etc.

1. Hot-dip galvanized T73 self-drilling anchor bolts is especially suitable for various acid and alkali fog and other corrosive environments, as well as in the field of geotechnical engineering with high requirements on service life and complex environments.

2. Epoxy T73 self-drilling anchor bolts is mainly suitable for the occasions where the formation and groundwater contain sulfides and chlorides, and are eroded by seawater, as well as in environments with stray currents or aggressive media.

3. Double anti-corrosion is a combination of two anti-corrosion processes of hot-dip galvanizing and epoxy coating. The steel parts are first hot-dip galvanized and then sprayed with an epoxy coating on their outer surfaces. The bolts treated by the two anti-corrosion processes have better anti-corrosion performance and longer service life, not only can resist common chemical corrosion, but also work under the electrochemical corrosion of acidic environment and stray current.


1. Drilling preparation

The drilling angle, length, mix ratio of slurry, and selection of drill bits should be determined according to the rock formation. Most tunnel advance support will use 51, 76 self-propelled bolts. Adjust the drilling angle of the rock drill according to the terrain and geological conditions.

2. Drilling and grouting

When the Self-Drilling Anchor bolts is long and needs to be spliced, the drill bit should be put on the front end of the first section of the anchor rod, and the tail end of the rod body should be connected to the grouting machine through the rotary grouting adapter. When drilling, grouting is carried out, and the slurry is pressed into the hole and into the cracks of the rock mass to consolidate the rock mass and stay in the deep stable rock mass, and bond together with the stable layer as the slurry solidifies.

3. Anchor rod connection length

When there is 30cm left in the first section of the anchor rod, stop drilling, put a connecting sleeve with artificial lubricant on the tail of the previous section of the anchor rod, and then connect the second section of the anchor rod, and so on, until the drilling reaches Design length. At the end of the drilling, the anchor rod is exposed at least 10cm, which is convenient for installing the arched backing plate and the ball nut.

4. Pull test

After the construction of the self-propelled bolt, the pull-out force value test of the bolt should be carried out to check whether it meets the design value of pull-out force. For every 300 bolts in the operation area, no less than 3 bolts should be randomly checked for pull-out force test to ensure that the construction effect meets the expected requirements.

The above is the answer to the question of how to support the tunnel crossing the pebble layer. The quality of the support affects the safety of the tunnel construction. It is necessary to adopt supporting materials with rich successful supporting cases and rich construction case verification.

The Self-Drilling Anchor bolts produced by Jiufu have many tunnel application cases, and can provide customers with a complete set of solutions. You are welcome to inquire.


For many manufacturers, we are not only recognized by our customers for our high-quality products, but also very good in detail services. Our product packaging will be different according to the surface treatment of the product and the way of transportation. For the self-drilling anchor bolts that have not been surface-treated, we will use a rain cloth for packaging to prevent corrosion and rust by seawater during transportation. For the self-drilling anchor bolts that are hot-dip galvanized and epoxy-coated We will take the packaging method to facilitate transportation and loading and unloading. We are proud that these packaging will be provided to customers free of charge.

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