Tunneling is a construction project which involves trenchless technology by utilizing specialized digging techniques that require heavy drilling equipment to construct small tunnels for sewers, pipelines, or other conduits. Typically, Tunneling or trenchless technology is deployed in high traffic areas which are not feasible for large trench digging such as busy roads or under large buildings. In most Tunneling operations, the machine is first pushed through an initial opening and then pipes are pushed behind the machine with immense force in a process called pipe jacking. This is process is repeated until the Tunneling machine reaches the opposite end at the reception shaft. The tunnels, while having a fairly small diameter, are still large enough to potentially allow an operator inside to operate the machine itself, though sometimes the operator controls everything from the surface using an array of advanced sensors, lasers, CCTV, and computers to guide the process.
Since Tunneling also involves moving a large amount of rock, dirt, gravel, sand, and other solids found beneath the surface, it needs an efficient way to dispose of this material. Typically, these materials are ground up by the tunneling machine and then pumped out through the machine using a combination of water jets and slurry pumps. The slurry system generally performs two functions. One is to remove the excavated ground spoils and cuttings by bringing them back up to the surface through slurry pipelines and hoses, and the other is to counterbalance any groundwater the machine may encounter using pressure sensors, eliminating the need for dewatering.
Tunneling Slurry System
The slurry system consists of a closed pipeline loop which circulates the slurry mix through the head of the Tunneling machine where excavated materials are ground up and picked up into suspension, carried out of the tunnel and deposited into settling tanks on the surface of the operation. The settling tanks help to dewater the slurry, thereby removing the solids, allowing the water to be recirculated back into the Tunneling machine.
Assisted by Slurry Pumps
Slurry pumps help with slurry system circulation to and from the slurry separation location. Slurry feed pumps assist with slurry feed flow above the jacking shaft assisted by booster pumps with slurry return flow from the Tunneling Boring Machine (TBM), while the mid pumps aid the booster pumps on extended length drives and slurry return pumps assist with slurry return flow from the jacking frame to the slurry separation location. All slurry pumps are VFD driven for variable flow volumes depending on the project specifications.
Typical Tunneling Steps
• Excavate shafts for the launching of tunneling equipment and reception of tunneling equipment at the opposite ends of the tunneling drive.
• Hydraulic jacks in the launch shaft push a Tunnel boring machine (TBM) into the earth using various cutterheads designed for the expected geology.
• Pipelines and hoses within the tunneling equipment containing slurry and mud transport the excavated materials to the surface for separation and disposal.
• Retract the pipe jacks and disconnect slurry lines and control cables.
• Lower a pipe or casing into the shaft and insert it between the jacking frame and the TBM.
• Reconnect slurry lines and control cables and advance the TBM another drive.
• Repeat the above process until the TBM reaches the reception shaft.
• Retrieve the TBM and trailing equipment using a crane after the pipeline has been installed.
Hebei Tobee Pump Co.,Limited