Vishal Agarwal, Director - Machino International

There is an inclination towards using conventional techniques such as DBM in the hydropower segment, while sectors like rails and roads will move towards advanced technologies like NATM; meanwhile, TBMs will continue to dominate the metro rails.

The New Austrian Tunneling Method (NATM) is increasingly being used in road and railway sectors.
Tunnelling in India has a very bright future. Currently, the Indian Government is concentrating more on roads, railways and irrigation tunnels in India, where most of the roads and railway tunnels are being built in the Himalayan range. Most of the ongoing and awarded projects are being built by the drill and blast method (DBM), which is the most common tunnelling method. Usage of tunnel boring machines (TBMs) is slowly increasing due to underground metro projects in many cities, with the. New Austrian Tunneling Method (NATM) being increasingly used in road and railway sectors.

In tunnel construction, geological surprises are one of the biggest challenges.
Complexities in the Himalayan region such as difficult terrain conditions, thrust zones, shear zones, in-situ stresses, rock cover, ingress of water, high level of seismicity etc. affect the construction. Tunnelling activity is also affected due to inadequate investigation, inappropriate budget and time allocation for site investigation, hurdles in acquisition of land, and improper assessment of geological-geotechnical conditions.

With regard to geological-geotechnical conditions, Machino International Pvt. Ltd. (MIPL) provides complete solutions for various types of Roof Support System, Rockbolts, Top Hammer Tools and Grouting Program. The Roof Support System and Rockbolts include Piperoofing / Forepoling System, Self-Drilling Anchor, Expandable Rock Bolts, Glass Fiber Rock Bolt, and Split Set for Mining Industry. Grouting Program includes products like inflatable packers, mechanical packers, grout pump – low pressure & high pressure for the grouting industry.


The tunnel market is expected to accelerate in coming years. This will, in turn, translate into huge opportunities for the contractors, consultants, equipment providers and material suppliers.
DBM will continue to be the preferred method for construction of hydro tunnels. The experience thus far indicates a greater inclination towards adoption of conventional techniques such as DBM in the hydropower segment. Other sectors like rails and roads will move towards adopting the advanced technology of NATM. Meanwhile, TBMs will continue to dominate the metro rails.Thus, there will be a higher demand for equipment like drill jumbos, shotcrete machines, excavators, loaders, etc. MIPL also offers rental service of these equipment to tunnel construction companies in India.

MIDAS – Pipe Roofing System/ Umbrella System
This is a support system used in loose ground conditions in conventional and mechanized tunnelling. It is used to enhance ground properties to stabilize and reduce risk in tunnel works. It is a method of supporting the tunnel by driving pipes ahead of excavation. It is also used in developing the portal sections and for the re-excavation of collapsed sections in underground works.


Fields of Application

• Weak Ground Structure
• Portal Sections
• Frequently Changing Ground Conditions
• Re-Excavation of Collapsed Tunnels
• Urban Tunnelling

The Installation of the Pipe Roof System is simple and quick and has the following effects:

• Reducing the ground loss by creating a boundary of stiff material between the soil and tunnel core.
• Stabilizing the ground in the area of newly excavated and getting unsupported excavation round.
• Distributing loads acting upon the tunnel roof above the freshly excavated round into the in-site ground ahead of the face and the lined tunnel behind the face.
• Confinement of the tunnel excavation area ahead of the tunnel face.
• Enhancing tunnel face stability by reducing loads acting upon the tunnel face.
• Reducing surface settlement.

Pipe Roofing Components

• Starter Pipe: First Pipe welded with Ring Bit on one end and female threading on the other end, which can be perforated / non- perforated as per the design requirement.
• Extension Pipe: Female threaded pipe for extension, which can be perforated/non-perforated as per the design requirement.
• Pilot Bit
• Drill Rods
• Grout Plug/Injection Cap
• Threads: Pipes have a trapezoidal thread with double start.
• Sizes of pipe roofing system: 76.1, 88.9, 101.6, 114.3, 139.7, 159,168.3

Typical Design

• 20-40 casing tubes per advance.
• Each pile 15 meters long, which gives about 12-meter tunnel advancement.
• Tubes are inclined 3-5 degrees from tunnel advance direction.
• Casing size and other specifications are determined by qualified tunnel engineers and geologists based on the soil/rock conditions.