The Interfels Concrete Vibrating Wire Stress Cell is used for measuring total stresses in tunneling process, mass concreting and rock walls in underground works.

The cell is installed either prior to shotcreting, concrete pour or within a slotted hole in the rock and incorporates a re-pressurisation tube to enable the cell face to be placed into intimate contact with the concrete should shrinkage occur during hydration, or with the rock face to take account of the slight overslotting needed to fit the cell in rock.

With over 30 years experience in Vibrating Wire technology, the Interfles' sensor is robust, has excellent long term stability and can be used with long cable lengths without any signal degradation.

The cell consists of a rectangular flat jack formed from two sheets of Stainless Steel welded around their periphery and filled with hydraulic oil. The cell is connected to a vibrating wire pressure transducer by a short length of stainless steel tubing forming a closed hydraulic system. Furthermore the cells are fitted with thermistors for correcting the effects of temperature variations on pressure readings.

The pressure cell is embedded in the medium to be monitored and an armoured cable connects the instrument to a terminal unit, portable readout unit or datalogger.