NATM tunnelling technology and theory

Recently IBODRILL employees attended a seminar on tunnelling and underground support. Tunnel project designers and Geo-drilling products manufacturers shared ideas on tunneling method and new technology.

Here is a brief review of how IBO self-drilling anchor bolts are applied in NATM tunneling and other ground reinforcement works.

The structure of tunnel

Construction method of mountain tunnel

NATM: new Austrian tunnelling method

The basic principle of NATM: Less disturbance, Early support, Ground measurement and Tight closure.

Sprayed concrete

Anchor Bolting: A kind of reinforced bar which is inserted into rock/soil body, for active reinforcement of surrounding rock.

Anchoring method of anchor bolt:

1. The anchor rod is embedded in the surrounding rock through the expansion of the anchor rod body or the rod end anchor head. – Mechanical anchor bolt
2. The end of the anchor rod body or the rod end is fixed in the rock mass by grouting. – Injection boring anchor

Related Terms:

– Full-length bonded rock anchor bolt

Anchor rod full fills binding material.

– Pre-stressed rock anchor bolt

Tension anchor rod for anchorage with tension requirements.

– Friction rock anchor bolt

Anchor rod by anchoring force between bolt body and hole wall.

– Self-drilling anchor bolt

The anchor rod itself has the integrated function of drilling the hole, grouting, and anchoring. Sometimes it is called SDA or IBO.

– Permanent rock anchor bolt

Consistent with the service life of the main project, the project can maintain stable performance and quality standards during the effective operation period, or have the repair and replacement conditions, the role of sustainable development of the anchor

– Temporary rock anchor bolt

The temporary anchor bolt can not reach the standard of the service life of the main project, only requires the anchor rod in the construction or the specific stage of the project, the normal working conditions of the project generally do not consider its role.

Below is a document about NATM technology and IBO self-drilling anchor application.