Pressure bulkhead machine

Bentonite slurry is used to support the face in soft ground in a pressure bulkhead machine. This represented a major innovation in mechanized tunnelling, particularly in coarse sediments not suited to compressed air. The bentonite slurry counterbalances the hydrostatic head of groundwater in the soil, and stability is increased further as the bentonite is forced into the pores of the soil, gelling once penetration occurs. The bentonite forms a seal on the surface. However, boulders in soils, such as till, create an almost impossible problem for slurry face machines. A mixed face of hard rock and coarse soil below the water table presents a similar dilemma. 

Known bulkhead presses of a design Novo-Cramatorsk machine works with a maximum effort P=45...75 thousand T are made on machinery with the limiting characteristic, and also with usage of existing mechanics of structural materials [2, 3], At the same time, on a known metal-working machinery with application of available structural materials, it is possible to produce offered bulky presses [6] with an effort P>160 thousand T, which one work at external hydrostatic pressure p, created in a hydrostat or by means of immersing of a press in demanded depth of a water environment [9]. 

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See also in sourсe #XX -- [ ]

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