Tunnels and metro
A tunnel stops when water comes in, the face will not stand, or a cavity opens above the crown. Those are the jobs we are called in for. Our crews work at the face with our own pumps and with resins we formulate for the water and the ground on that site.
From Himalayan rail tunnels to a metro shaft in Delhi and a micro tunnel beside the sea.
A leak in a tunnel isn’t only water. It is time, money and reputation draining away, and the grout has to work the first time.
We probe before we grout, choose the chemistry for the water we find, and close each job against a measured result: inflow, settlement or advance.
Industry challenges
What stops a tunnel
Water ingress
Inflow under head through fractured rock or loose ground: the largest single source of delay and cost overrun underground.
Cavities and overbreak
Voids above the crown after a collapse or overbreak, which keep loosening and carry water, and which shotcrete cannot fill economically.
Weak and shear zones
Fault gouge, clay-filled joints and running ground that will not stand long enough to be supported.
Trapped machines and old tunnels
TBMs held in saturated ground, and tunnels in service that leak through their linings and cannot be closed for repair.
- 1Note 1: Water-bearing joints and fractures in the rock around the tunnel.
- 2Note 2: Leaks through cracks and construction joints in the lining.
- 3Note 3: Holes drilled through the lining into the rock, in a pattern set by the leak map.
- 4Note 4: A packer seals each hole, so the resin goes into the ground and not back into the tunnel.
- 5Note 5: Water-reactive PU (DrucHyd 2C) expands on contact with water and fills joints and voids behind the lining.
- 6Note 6: The treated ring cuts the water off before it reaches the lining.
- 7Note 7: Inflow is mapped and measured before treatment, and measured again after it.
Our solutions
What we do in tunnels and metro
Tunnel water ingress control
Leaks and inflow stopped in tunnels, shafts and underground structures.
Pre- and post-excavation grouting
Water cut off and weak ground consolidated ahead of the face; voids closed behind it.
Cavity and void filling
Voids above tunnel crowns, behind linings and under slabs filled without loading the support.
Tunnel rehabilitation
Old and operating tunnels: seepage stopped, ground consolidated and lining repaired, under traffic.
Rock bolting and self-drilling anchors
Rock bolts, self-drilling and prestressed anchors for tunnels, portals, slopes and caverns.
TAM grouting
Staged grouting through sleeve pipes for shafts, foundations and deep excavations.
Permeation and chemical grouting
Weak, loose or wet ground strengthened and sealed by resins and gels that fill it without moving it.
For shielded TBM drives we also make TeraSeal tail-skin sealants. TeraSeal →
Our clients and success stories
Tunnels and metro work on record
USBRL tunnels T-1, T-3 and T-5, Katra
Heavy water ingress in Himalayan tunnels, controlled with our resin, grout design and crews: recorded by Northern Railway at up to 2,500 litres per minute.
T-49B escape tunnel, Arpinchala, USBRL
Cavities in a Himalayan escape tunnel treated with low-foaming and water-reactive PU resins: one of the two largest chemical grouting jobs we have held.
Delhi Metro CC-04, Azadpur
Two tunnel boring machines held 30 m down in loose, saturated sand. We sealed and consolidated the ground so they could be retrieved.
Parsik tunnel, Thane–Kalyan
Seepage controlled in a brick-lined railway tunnel built in 1916, on a busy main line, without stopping the trains.
Micro-tunnel pit, Pipavav
Seawater pouring into a micro-tunnel pit through a crack, after repeated attempts to seal it had failed. Sealed up to 85 per cent by grouting.
Tunnel T-77D, USBRL, Banihal
A collapse at the crown left an 8 to 10 m cavity in fractured, water-bearing rock, and the ground above began to settle.
- Tunnel T-12, ManipurPU grouting in soil at the portal, shaft and adit: PuTeRA grout supplied and injected by our crew, 2026Work order, February 2026, amended July 2026. Work order
- NFR tunnel project, ManipurGrouting material supply, 100 t Supply
- USBRL tunnels T-3 and T-5Self-drilling anchors and other products supplied, and DrucHyd 2C grout designed and applied to control water ingress, 2016Work satisfaction certificate, July 2016. Certified
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