Summary Reader Response draft 1
According to Harding,(2017), Mixshield is a slurry tunnel
boring machine (TBM) that uses an air bubble to control and support pressure at
the face made by Herrenknecht. This is further explained by Herrenknecht. The
TBM has an automatic air cushion that precisely controls the face support
pressure in the excavation chamber (Herrenknecht,2024). It also offers an array
of powerful cutting tools such as cutting knives and disc cutters. It is
enhanced by jawcrushers positioned in front of the intake screen to further
breakdown boulders and stones into conveyable size pieces (Herrenknecht, 2024). According to Herrenknecht and Rehm, the TBM can
excavate and build a ring around the machine continuously (Herrenknecht and Rehm).
This is supported by Herrenknecht’s claim that the TBM is able to do so with
the help from its erector and thrust system. The erector is controlled by a
remote and it positions the segments during ring building whereas the thrusters
are positioned around the circumference which pushes the shield forward,
leaving behind the previously built ring (Herrenknecht,2024).
The Herrenknecht Mixshield emphasises on safety and
efficiency. It is established as an incredible tool for boring, laying the
foundation for seamless project completion and ensuring a streamlined and
secure tunnelling process.
The Herrenknecht Mixshield prioritize safety by using air
pressure. According to Herrenknecht (2024), There is a wall inside the excavation chamber that divides it into
two parts. The front part is filled with a special fluid to fully support the
tunnel's face during digging. But towards the back, the fluid level is lower,
just above the machine's axis. To keep the tunnel stable, they use a cushion of
compressed air above. Both parts of the chamber can communicate through an
opening in the bottom of the wall. This feature enhances safety by providing stability.
By fully supporting the tunnel face with suspension fluid in the front section,
the risk of collapses or cave-ins is minimized. This ensures the safety of
workers and prevents accidents underground. Also with controlled pressure, the
use of a compressible air cushion in the upper section allows for precise
control of pressure at the tunnel face. This helps maintain stability and
prevents excessive pressure build-up, reducing the likelihood of accidents or
structural damage.
The Herrenknecht Mixshield is an efficient TBM because it
has a feature against clogging to keep
things moving smoothly. Herrenknecht (2024) stated that the cutting wheels have a design that lets material flow
freely through the centre, reducing the chances of blockages. Herrenknecht improved how the fluid used in tunnelling
moves through the system in areas where blockages are more likely, making sure
it flows well. The separate systems of the machine have a system to handle
materials. The user can adjust the flow with nozzles in the cutting wheel arms, the
walls, the crusher, and the intake screen. Lastly, the chamber design helps
keep things moving. Features like smooth edges and surfaces, coatings on parts
of the machine, fewer openings in the walls, or optional buckets at the back
all help stop blockages. These measures make sure the tunnelling process can keep on track, with fewer interruptions caused by blockages. It also helps the
equipment last longer.
The Herrenknecht Mixshield ensure seamless project completion and a streamlined secure tunnelling process by enhancing tunnelling efficiency and safety. According to Herrenknecht (2024), specialized techniques have been developed for challenging soil conditions. In cohesive soils, an isolated invert system prevents material build-up and pressure fluctuations by directing material flow away from critical areas. This minimizes the need for cleaning operations and ensures stable tunnelling conditions. Additionally, maintenance of excavation tools is optimized through controlled lowering of tunnel fluid levels using compressed air, allowing for effective tool inspection and servicing. Professionals may be employed in high-pressure conditions, and training programs are provided to streamline tunnel work processes.
Reference List
Harding, D. (2017, August 1). Redefining the Industry. Https://www.Robbinstbm.com/Mixshield-Crossover-Hybrid/.
Herrenknecht M. Ulrich Rehm (2003, March 28). Mixshield Technology. chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://inside.mines.edu/UserFiles/File/earthMechanics/seminar/04_soft_ground_tbms_slurry.pdf
Herrenknecht (2024) Mixshield. https://www.herrenknecht.com/en/products/productdetail/mixshield/
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