Environmental Engineering Reference
In-Depth Information
S
Deflection (in.)
N
W
Deflection (in.)
E
0
1
2
0
1.5
3
−
2
−
1
−
3
−
1.5
1600
1600
1600
1600
1560
1560
1560
1560
Elev.
(ft)
Elev.
(ft)
1520
1520
1520
1520
1480
1480
1480
1480
Rt
Sl
1440
1440
1440
1440
−
2
−
1
0
1
2
−
3
−
1.5
0
1.5
3
Cumulative deflection
direction X
Cumulative deflection
direction Y
N
W
3.0"
FIGURE 4.17
Inclinometer readings of failure zone in slope taken over a period of 11 months. (Courtesy of Woodward-Clyde
Consultants.)
Instrument
A row of electrical transducers is wired in parallel and mounted on a waterproofed brittle
backing strip about 15 cm (6 in.) apart.
Installation and Operation
The strip is mounted on a PVC pipe placed in a borehole drilled downward into a slope
to intercept a potential failure surface. When shear displacement at any point exceeds 2 to
3 mm, the electrical circuit is broken. The failure surface is determined by measuring
resistances at the top and bottom of the strip (Broms, 1975). The strip can be connected to
an automatic recording and alarm system.
