Monitoring - Rock Mechanics Based on an Anisotropic Jointed Rock Model - page 577

Figures 17.23 and 17.24 show hydraulic anchor load cells mainly consisting of an an-
nular fl at jack fi lled with hydraulic fl uid. When the fl at jack is loaded by an increase of
the anchor force, the hydraulic fl uid is pressurized. The fl uid pressure is converted into
a force and can be read at a dial gauge of a manometer (Fig. 17.23). Where remote data
transmission is required, the fl uid pressure can be converted into an electrical signal (Fig.
17.24). The measuring accuracy of hydraulic anchor load cells is specifi ed as

0.5%

(Fecker 1997).

Figure 17.23 Hydraulic anchor load cells with manometer (Glötzl GmbH)

Figure 17.24 Hydraulic anchor load cell with electric pressure converter (Glötzl GmbH)

Other types of load cells measure the anchor force using strain gauges, vibrating wire
strain sensors or optical fi ber sensors.