The Stabilization of Tunnel Portals

Tram, train and metro tunnels offer passageway for thousands of commuters and goods every day. Tunnels are indispensable in today’s busy and congested society. It is fair to say that tunneling remains one of the most intricate civil engineering challenges globally. These technological masterpieces have defined the finest engineers and technologies over the years. These horizontal underground passageways can occur through either a natural occurrence or human effort.

mining and tunneling industries

Mining and tunneling industries involve a number of risks or hazards including rock falls, scaling, mud inflow and explosions. Tunnels sometimes collapse in avoidable circumstances, just because engineers rushed through. Collapse may occur in the following manners:

  • Face/crown collapse
  • Collapse along finished tunnel length
  • Tunnel portal collapse

Because of the limited escape options, designers must identify and solve portal problems as early as possible to ensure safety of people and equipment. The good thing is that each of these challenges has control measures. Ground stabilization techniques such as probe drilling, tunnel portal inspection, rock bolting, drainage pipe installation and grouting come in handy. One of the best ideas is to use a highly effective method for stabilizing tunnel portals- hollow bar installation.

hollow bars and rock drills

The hollow bar system is easily the most popular method for holding in position collapsing or loose soil at tunnel portals. A threaded steel bar is drilled into the soil and grouted into place. The hollow center in the bar acts as a conduit for simultaneous grouting and drilling. It features a rope thread that connects to drilling equipment. Drill bits, rock bolts and soil nails normally accompany the hollow bars in the portal stabilization process.

Being results of cold rolling manufacturing process, the hollow bars feature refined grain structure. With incredibly high yield strength, the material is suitable for a wide range of applications. Previous users will confirm that these bars offer excellent support in different ground conditions and types of soils around the tunnel portal.

Final Word

According to the Safety and Health Regulations for Underground Construction, portal openings, access areas and adjacent areas shall be secured and guarded for safety within the portal and in access areas. Demand is increasing for the state-of-the-art measures. You cannot go wrong with hollow bars installed using hi-tech rock drills from