Microtunneling Systems

Microtunnel Boring Machines (MTBMs) install gravity flow pipelines that require precise line and grade in poor soil. Microtunneling is a remote controlled, continuously supported pipe jacking method. Standard center drive and face access, periphery drive MTBMs are sized in the 30-114-in. OD range. Microtunneling operations are managed by an operator in an above ground control container alongside of the shaft. Soil excavation takes place by infusing the soil with slurry at the face of the bore and cuttings are forced into slurry inlet holes in the MTBM’s crushing cone for circulation to and from a slurry separation plant through a closed system. A complete slurry microtunneling system is commonly comprises a pipe specific MTBM, control container, guidance system, remote hydraulic power pack, keyhole jacking frame, a series of pumps, water cooling tank, slurry and additional lines, and a slurry separation plant. The launch shaft is outfitted with a pit seal to prevent shaft flooding and a project specific thrust block to distribute jacking force.

Technical Data

Microtunneling Systems Overview

  • Most suitable for saturated and flowing materials and pressurized soil under the water table, minimizes ground surface settlement
  • Drive lengths up to 1,000-lf.+
  • Two types of MTBMs – Center drive MTBMs and Face Access, Periphery Drive MTBMs for extended lengths to perform tooling changes
  • MTBMs are remotely controlled
  • Soil excavation takes place by infusing the soil with slurry at the face of the bore
  • Common types of pipe: VCP, RCP, CCFRPM, FRP, PCP, steel casing
  • Active laser guidance system
  • Slurry separation equipment for soil management

 

Center drive Microtunnel Boring Machines (MTBMs) in standard sizes of 30 – 74-in. OD, accurately install pipe in virtually any ground condition, allowing for operation in high levels of ground water. MTBMs feature high pressure jetting nozzles, an articulated steering joint with three-point steering control, and hydraulically activated dirt wings to minimize MTBM roll. The guidance system relays all critical operation data to the control container using proprietary control software programs. Additional MTBM attributes include a live, one-way audio system and camera allowing for system monitoring during operation, gas detector and submersible pump. MTBMs can be outfitted with increase kits for adaptability. The soft ground and mixed ground cutter heads and crushing cones are hard faced to withstand wear. Cutter heads can be customized for specific ground conditions.

Face access, periphery drive Microtunnel Boring Machines (MTBMs) are available in standard sizes of 72-114-in. OD to precisely complete extended and curved tunnels* with exceptional drive and cutting torque. This new generation of MTBMs enables face access to replace cutter head tooling. The periphery drive, face access MTBM features an on-board electric over hydraulic power pack for cutter head drive with low, medium, and high torque modes for accurate control in changeable geology. Back-loaded tooling mounts on the cutter head make access and replacement of worn tooling a simple process. Soft ground, mixed ground and rock cutter heads and crushing cones are hard-faced to withstand wear. Cutter heads can be customized for specific ground conditions. The SL82P-SL114P face access, periphery drive MTBMs can be configured for use with a compressed air lock package.

*Extended and curved alignments are achieved with the use of the AZ100 Total Guidance System.

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