________________ An efficient separation plant is the basis for the successful use of slurry-supported tunnel boring machines, such as AVN Machines , Mixshields or Shaft Sinking Machines . Efficient and sequential processes separate and remove the excavated soil from the bentonite suspension – a mixture of water and thixotropic clay. The cleaned suspension is then transferred back to the slurry circuit.
+ Optimum adaptation to the tunnelling technology and ground conditions
+ High g-forces ensure the removal of large amounts of solids and efficient dewatering
+ Sophisticated screening technology: low space requirements and rapid replacement system for the quick adaptation of the screening elements to the changing geology
+ Container-based modular construction ensures quick assembly/ dismantling of the plant with optional high-performance sound insulation
+ Computer-supported monitoring of key performance parameters
Efficient separation, powerful performance
Herrenknecht separation plants are optimally adapted to the requirements of the tunnelling process and separate the slurry suspension completely from the solid particles consisting of gravel, stone and sand in various grain sizes. A powerful combination of state-of-the-art screening technology and hydro-vacuum cyclones with high g-forces results in depositable excavated material. Complete removal and dewatering to achieve low levels of residual moisture in the excavated material as well as the geology-dependent addition of bentonite and other additives are the defining features of an efficient separation process. The lower the water content, and thus the weight of the excavated material, the lower the costs for disposal. What is more, fine particles left in the suspension impair the excavation speed of tunnelling due to the low resorption in the slurry of solid particles in silty and clayey soils. In this case, the additional use of filter presses and centrifuges prevent the suspension from thickening.
One strength of slurry shields is their versatility when used in heterogeneous ground conditions. The screening elements must be adjusted in the separation plant if the soil and rock conditions vary. With the rapid replacement systems made by Herrenknecht, this is possible without any additional tools while the TBM is at a standstill during ring building. The use of durable and maintenance-friendly polyurethane or steel screens also has a positive effect on the cost effectiveness and efficiency of the entire separation process.
Mobile and low-noise
For the standardized setup of the Herrenknecht separation plants, a modular container system is used, which can be extended, reduced or relocated quickly and easily. This allows for flexible adaptation to the particular needs and ensures high speed and low costs for assembling and dismantling. The internal setup of the separation plant is also based on the modular principle. The regular maintenance, any repairs or the replacement of spare parts is thus considerably easier. Upon customer request, the individual components can be encased with noise insulation, making the machine capable of low-noise operation in urban areas.
Controlled interaction of tunnelling and separation
A look at the displays in the control cabin of the TBM and the separation plant provides updated data about the utilized capacity and performance of the tunnel boring machine and the processes in the separation plant. By exchanging information with one another, the personnel in the two control cabins ensure an ideal interplay of both systems.