Environmental Engineering Reference
In-Depth Information
1. Install strain meter
2. Overcoring slot
3. Rock mass stress relieved
FIGURE 4.31
Strain meter for residual rock stresses.
Rock face
Measuring point
10"
Fressinet flat jack
18" (variable)
To hydraulic jack
Grout
10"
FIGURE 4.32
Flat jack test to measure
in situ
rock stresses.
Borehole Devices
Devices
Residual stresses can be measured in boreholes with the borehole deformation meter
(Figure 4.33a),
the high-modulus stress plug or inclusion stress meter (Figure 4.33b), or the
Leeman “door-stopper” strain gage (Figure 4.33c).
