Question

application for tunnel boring machine?

Answer 1

A Tunnel Boring Machine (TBM) is a machine used to bore or excavate tunnels through soil or rock strata. The boring using TBM will create a circular cross-section of tunnel having diameters ranging from 1m (3.3 ft) to 17.6m (58 ft). But for tunnels having a diameter of less than 1m, TBMs are not preferred. Due to the less disturbance to the surrounding environment, TBMs are largely used as an alternative to the drilling and blasting methods in rocks and hand mining techniques in soil.

TBMs are mainly used in two fields:

1. Tunnel excavation ( for both highway and railway tunnels)

2. excavation of mine drifts

The tunnel boring machines can be used for excavation in straight directions and also for small curved directions. The usage of TBMs is only economical if the length of the tunnel is greater than 1km. Although the operation consists of TBMs in tunneling, the starting length (usually about 100m) is excavated using drilling or blasting.

Earlier, the TBMs used in mining have not been nearly as successful as in civil tunneling (highway or railway tunneling). The shortcomings encountered are:

1. Lack of ability to determine and cope with the unexpected ground conditions such as fault zones.

2. Low machine utilization rates due to inexperienced crew members

3. Use of refurbished parts for the construction of TBM parts that are not originally designed for drilling purposes.

4. The limited power supply available on the machines for operations

But these shortcomings are successfully eliminated by technological advancements and scientific breakthroughs in this field. This results in the successful application of TBMs in mining operations.

Two most recent successful application of TBM technology is at the San Manual Copper mine and Stillwater Platinum mine in the United States.