Environmental Engineering Reference
In-Depth Information
FIGURE 4.16
Slop indicator inclinometer, grooved casing, cable, and digital readout.
Deflectometer
Application
Deflectometers are used as permanent installations in boreholes to measure movements
normal to the hole axis such as that occuring along a fault zone, or along some other weak-
ness plane in a rock mass.
Operation
The elements of the deflectometer are illustrated in
Figure 4.19.
Any movement in the
mass perpendicular to the axis of the hole causes an angular distortion between consecu-
tive rods or wires, which is monitored by transducers. Chains of deflectometers can be
made with eight transducers to depths of about 60 m (200 ft). The system is connected to
a remote readout and can be attached to an early warning system. Precision is about 0.025
mm (0.01 in.) for a 5 m distance between the transducers.
Shear-Strip Indicator
Application
Shear-strip indicators are used to locate the failure surface in a moving earth mass.
