The different methods of tunnelling in soft soil are:

1. Needle beam method.
2. Linear plate method.
3. Forepoling method.
4. American method.

5. English method.

6. Needle beam method:

7. This method is useful for tunneling in the soft ground whose roof soil can stand without support for few minutes.
8. In this method 5 to 6 meters long R.S. joist or timber beams are required in addition to other timber boards and struts.
9. This method requires large number of jacks which cause obstruction in the efficient working of the laborers.
10. For tunneling in soft ground it is more economical than other methods.

Sequence of Working:

• The needle beam method is adopted in terrains where the soil permits the roof of the tunnel section to stand without support for a few minutes.

• In this method, a small drift is prepared for inserting a needle beam consisting of two rail steel (RS) joists or I sections and is bolted together with a wooden block in the centre.

• The roof is supported on lagging carried on the wooden beam.

• The needle beam is placed horizontally with its front end supported on the drift and the rear end supported on a vertical post resting on the lining of the tunnel.

• Jacks are fixed on the needle beam and the tunnel section is excavated by suitably incorporating timber.

• This method of tunnelling is more economical compared to other methods.