Environmental Engineering Reference
In-Depth Information
Dial gage mount
Concrete
0.40
1¼-in. rod
Flange
Rubber spacer
Grout
1-in .
−
dia.
galvanized pipe
3-in .
−
dia.
galvanized pipe
5.00
(c)
2.00
1.00
Clamp
1.00
Impervious
bag
HX
(a)
(b)
FIGURE 4.13
Settlement point installation: (a) schematic of the settlement point (depth are in meters); (b) clamp and bag
being tested on the surface; (c) dial gage mount and protection.
Borros Points
Application
Borros points are simple and inexpensive devices used to monitor settlements from the
compression of soft soils.
Instrument and Installation
The Borros point consists of an anchor, with prongs folded to the sides of a driving point.
It is attached to a ¼-in. rod contained within a 1-in. pipe that is pushed or driven through
a 2½-in. casing to the observation depth (
Figure 4.14)
.
The 1 in. pipe is held fixed while the
¼ in. pipe is advanced about 1 in., extending the prongs into the soil. The 2½-in. casing is
removed and the 1-in. pipe withdrawn a short distance. The ¼-in. rod, attached to the
points, is free to move within the 1-in. pipe. Settlements are determined by periodically
surveying the elevation of a cap on the pipe.
