Geokon 4855, Инструкция по эксплуатации, Страница: 8 / 20

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Lugs are provided on the back of the upper plate for welding to the rebar cage as shown in
Figure 1.
Lugs are also welded to the lower plate for attachment of short lengths of rebar, which are
designed for pre-embedment in a concrete cone or cylinder, covering the entire lower plate. This
cone, or cylinder, depending on the shape of the bottom of the excavated shaft, prevents the
formation of voids beneath the pressure cell caused by the entrapment of air or water.
During concrete curing, temperatures very often rise and will cause the cell to expand in the still
green concrete. On cooling, the cell contracts leaving a space between it and the surrounding
concrete which, if allowed to remain, might prevent the transmission of pressures from the
concrete to the cell. To overcome this, provision is made so that the cell can be inflated until it
comes back into perfect contact with the concrete on both surfaces. This re-inflation is performed
from the surface through a hydraulic line operating through a check valve. (An alternative
method, using a pinch tube and remote crimping device, is also available).
The vibrating wire sensors are standard Geokon Model 4500H transducers inside all-welded
housings. The sensors are hermetically sealed and are connected via waterproof connectors to an
electrical cable leading to the surface. The sensor housings also incorporate a thermistor that
permits measurement of temperature at the cell location.