Is Self-drilling Anchor Bolt Installation Tough？

Time:2022-04-11From:sinorock View:

In many geotechnical construction, self-drilling anchor bolt system is widely applied to support the unstable conditions. How about the installation of self-drilling anchor bolt? Is it tough? Today, Sinorock will introduce you the self-drilling anchor bolt installation process.

self drilling anchor bolt

What’s the composition of self-drilling anchor bolt system?

How to install the self-drilling anchor bolt?

Where can the self-drilling anchor bolt be used?

What’s the composition of self-drilling anchor bolt system?

The self-drilling anchor bolt system consists of a hollow bar, a sacrificial drill bit, a coupler extending the hollow bar, a plate, a nut, and a centralizer.

self drilling anchor bolt

Hollow Bar

It is made of high strength steel to ensure the ultimate load and the yield load. The outer diameter of a hollow bar ranges from 25mm to 200mm.

The surface thread of every hollow bar can be rolled to meet the ISO standard and can be connected with standard drilling rig.

Drill Bit

In order to drill in different conditions successfully, what matters most is that the selection of a proper drill bit and it’s up to the ground condition. See below example.

RQD of Current Rock	UCS of Current Rock (Mpa)	Outer Diameter (mm)	DrillingDepth (m)
100%	＜10	42	15
		51	12
		76	12
		90	12
75%	＜12	42	15
		51	12
		76	12
		90	12
50%	＜12.5	42	15
		51	12
		76	12
		90	12
30%	＜10	42	15
		51	12
		76	12
		90	12

To prevent the hollow bar and drilling bit being corroded, the surface of self-drilling anchor bolt can be painted with epoxy, or hot dip galvanized.

How to install the self-drilling anchor bolt?

Mostly, the traditional hollow bolt is installed as following steps.

First, we must use a drill rod to drill a hole with a rig in the rock or soil. And then, we pull out the drill rod and put the hollow bar in. What’s following is grouting and anchoring. The whole construction is very complex. What’s worse, when processing at unstable ground, the drilling hole will probably collapse and no way is the hollow bolt put in. If this happens, the entire program would be postponed, and we can’t ensure the anchoring effect for further use.

On contrary, the installation of self-drilling anchor bolt system is much easier.

We can only drill once to complete the grouting and anchoring process since the hollow bar of self-drilling anchor bolt is not only a drill rod but also an anchor bar. It is hollow, so we can drill and grout at the same time.

Where can the self-drilling anchor bolt be used?

self drilling anchor bolt installation

The self-drilling anchor bolt system is widely used to support tunnels, to reinforcement the slopes, and as micropiles of some constructions.

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