Tunnelling & drilling

Pumps for Every Tunnelling Application

Trenchless pipe laying

Trenchless technology for laying and repairing utility pipes for mains water, gas and sewage are well established. Micro-tunnelling machines (mTBM) are remotely controlled and typically cut up to 4m diameter tunnels. Operations are conducted from a vertical shaft which also serves as a drainage sump for ground water draining back from the tunnel. Electrically driven Audex pumps are built for this type of complete dewatering procedure, being able to pump dirty water contaminated with abrasive rock cuttings and mud solids to high head heights. They are also relatively quiet in operation and emit no emissions during operation, two prerequisites for working close to site operators in tunnels and pits.

Pipe Ramming

Rather than drilling, this method uses a percussion action to push metal pipe into solid clay, sand or earth. The pipeline is then cleared of material using high-pressure water to cut away and wash out the spoil using a multi-stage high pressure centrifugal water pump.

Pipe Jacking

The difference between this technique and ramming is that with jacking the borehole is first cut using a boring machine, then a pipe section is pushed into the space using hydraulic force. This method usually requires workers to access into the tunnel so is only used for larger diameter pipelines.

Horizontal Directional Drilling (HDD)

This involves 3 stages; with rotating rods pushing and pulling from one end to the other, between surface rigs at each end. Straight lines can be cut through embankments, or it can be steered to take a predetermined path such as a shallow curve underneath a river. First a pilot hole is drilled, then a wider reamer head is attached and this is rotated back through the hole. Finally, the actual pipe or tunnel lining is pulled through to complete the installation. Having water or drilling fluid pumped in is an important part of effective HDD, as it keeps the cutting head cool and clears the cut debris out of the tunnel. This requires robust horizontal slurry pumps that withstands abrasive sand or grit and passes solids without blocking.

Boring machine paths are sometimes guided by altering the direction of high-pressure water jets on the cutting head, making them extremely accurate and controllable for depth and direction.

Pumps for Drilling Mud Fluid

To aid lubrication and to wash-out the drilled material, a bentonite clay slurry is pumped along the drilling rods using a special peristaltic slurry pump. This drilling mud (drilling fluid) draws out the earth from the tunnel so is pumped to a treatment system with a quarry-water type dewatering silt pump. It is then cleaned and recycled through the system in a closed loop, to save on costs of additives and waste disposal. Methods of recycling drilling fluid can include vibrating screen filters, high-fidelity hydrocyclone separation and EnviroHub settlement tanks and dosing units.

TBM Slurry Pumping

Beyond 4m diameter, tunnels of this category are usually for super infrastructure projects like underground railways and motorways. The largest TBM (tunnel boring machine) can cut tunnel diameters over 17m for multi-lane motorways and double-deck trains to pass through.

Many of the larger Tunnel Boring Machines (TBM) use industrial slurry pumps to transport the cuttings of rock, sand and soil from the cutting face back down to the tunnel entrance. A high-volume centrifugal slurry pump needs to transfer up to 1500cbm an hour on large TBMs and are essential for continual operation. The pump chamber and associated piping needs to be made with wear-resistant material such as high-chrome or rubber linings. Gromatex piping is ideal for heavy-duty work, moving abrasive solids laden slurry over long distances. It is supplied in sections and pre-formed bends and can be quickly extended or have individual sections replaced when needed.

Once the slurry reaches the surface it is dewatered and separated with the water looping back through the system and the solid minerals being graded for construction materials or land remediation.

Tunnel Grout pumping

Large TBMs cut and remove the earth, as well as conveying, holding and placing ring sections to make the tunnel as they move along. Once a ring section is completed, hydraulic arms release their hold and the TBM moves forward. These rings are then often grouted and any gap between the tunnel wall and the cutting can be backfilled with mud or cement. A LSM fast peristaltic pump is recommended for pumping cement and grout.

High-pressure water needs in TBMs

It takes considerable pressure to push the cutting head of tunnel boring machines into the cutting face, especially if it is into hard rock. Whilst this can sometimes be done with compressed air, it often makes a better solution to use water to create the required pressure, especially if water is being pumped there to remove the cuttings. The hydraulic pressure is controlled by variable-frequency drives on two pumps - the supply pump and discharge one.

You can rely on Atlantic Pumps to supply heavy-duty pumps of the highest quality, backed by sound technical knowledge and one of the fastest response times in the construction pump industry. We hold a large stock of centrifugal pump parts for our own Intrax family of pumps and for OEM after-market brands, as well as pump repair and engineering in-house and on-site.

Atlantic pumps’ mission is to reduce downtime and maintenance in tunnelling and drilling operations. If a pump fails on a drilling job it can hold the entire operation up, so downtime is not an option. If you are experiencing rapid wear, high energy usage or concerned about downtime waiting for parts or service, call us today on phone number 0800 118 2500.