Tunneling and Mining

Typical Applications

Soft-eye FRP wall for easy penetration of TBM through retaining walls.

For roof and wall bolting in both temporary and permanent applications

Our Solutions

Innovative FRP solution for efficient tunnel excavation ASTEC™ FRP combination bolt is a unique and innovative Glass Fiber Reinforced Polymer solution precisely designed by Dextra. In unconsolidated excavation areas, like steel bolts, FRP Combination Bolts can be automatically installed by a jumbo machine or manually installed. Thanks to the characteristics of the FRP material, Combination Bolt can easily be cut by common excavation equipment, which makes the product an ideal solution for temporary application for tunnel excavation projects. Eurocode 2, BS 8110, DIN 1045, ACI 318, IBC, AASHTO, ASME Sec III Div 2.

Tunnel breakthrough made easy with FRP rebar ASTEC Soft–Eyes allow the penetration of Tunnel Boring Machines (TBM) through diaphragm walls and secant piles. This unique technology uses cuttable Glass Fiber Reinforced Polymer (GFRP) reinforcement as an advantageous replacement for conventional steel rebars. The Soft-Eye technology was developed by Dextra in 1996 and successfully implemented for the first time on Bangkok MRT subway stations. The Soft-Eye technology has since become a standard concept in the design of launching/receiving shafts and subway stations. We have successfully supplied over 500 soft-eyes on all continents. Dextra offers an integrated turnkey solution that includes design, optimization, manufacturing, logistics, and on-site training.

GEOTEC lattice girder systems are lightweight, three-dimensional curved steel frames that are composed of main bars, secondary bars, connection plates, footplates, and stiffeners.

The lattice girder can provide immediate support for tunneling environments.

The radius of the bending is tailor-made to meet each project’s demands.

Umbrella Pipe

A pre-support system for weak grounds

GEOTEC™ umbrella pipe system is a pre-support in soft and weak ground conditions. The system comprises steel pipes installed from the tunnel face to form a roof to stabilize the tunnel headings. Distributing the load in the longitudinal direction can decrease deformation during excavations.
The supporting mechanism of the umbrella pipe method is to stabilize the excavation face in both the transverse and longitudinal directions by an arch-like reinforced zone. The support system can be divided into three different aspects:
Radial support Longitudinal support
Subdivision of open areas of the unsupported zone

Steel Combination Bolt

Immediate and permanent rock bolting solution GEOTEC™ steel combination bolt is suitable for the most stringent requirements. A mechanical bolt combined with a corrugated pipe and a double grout layer all along the tendon to provide both high bonding and protection against corrosion (similar to Double Corrosion Protection / DCP). It is initially installed for immediate support by the use of an expansion shell, to be fully grouted at a later stage allowing it to be classified as permanent application. bent reinforcement bars while being simpler and faster to install.

Cuttable mining anchor GEOTEC™ FRP solid rock bolt is a rock-bolting system based on a fully threaded GFRP tendon. It is specially designed for the following applications: Face-bolting and temporary applications: The cutability of FRP makes it the ideal solution for face bolting or any other tunneling/mining application where further excavation is required. Cohesive soil & hard rock. GEOTEC FRP is installed into pre-drilled holes. Installation with grout or with resin cartridges.

Drilling, grouting, and anchoring, in one!

GEOTEC Steel self-drilling rock bolt is a rock-bolting system based on a fully coarse threaded hollow bar.
It is especially recommended for the following applications:
Roof and wall bolting.
All ground conditions. GEOTEC self drilling rock bolts do not require pre-drilling a hole, therefore making it usable even in soft rock conditions.
Installation with grout. The hollow steel anchor rod also acts as a grouting pipe to ease setup. For non-grouting applications, please refer to the mechanical anchor or expandable friction bolt.
Temporary or permanent applications. With optional epoxy coating available for permanent applications.

FRP hollow rock bolt

ASTEC FRP hollow rock bolt is a rock-bolting system based on fully threaded hollow GFRP bars. It is specially designed for the following applications:

Face-bolting and temporary applications: The cut-ability of FRP makes it the ideal solution for face bolting or any other tunneling/mining application where further excavation is required.

Cohesive soil & hard rock conditions: ASTEC is inserted into a pre-drilled hole. For a non-cohesive soil environment, refer instead to FRP Self-Drilling Bolts.

Installation with grout: The hollow GFRP anchor rod also acts as a grouting pipe to ease installation.

Tunneling and Mining