Page 3-1
Rev. 0
3. Electronic measurement
3.1.
G en eral syst em d escrip t io n
The uplift pressure meter is designed to measure uplift
pressure in the foundation of the dam. The vibrating wire
uplift pressure meter is fitted on the pipe coming in to the
instrumentation gallery from the foundation rock. Refer to
figure 3.1 and the table on this page.
The uplift pressure measuring device consists of a vibrat-
ing wire uplift pressure meter and a perforated/non-
perforated pipe of 50mm to 63mm
φ
with adequate
strength and connecting accessories. A system of piping is
installed at several stations in the dam in the first lift just
above the contact between the foundation rock and the
base of the dam. The pipes extend into one or more of the
lower galleries in the dam. Alternatively, holes may be
drilled from the gallery down to the level upto which the
drain pipes have to be installed. Drain pipes extend below
the dam, both on the upstream and downstream side. The
other end of the pipe is brought into the gallery where it is
connected to an uplift pressure meter through other acces-
sories listed below.
Sl.
Description
Qty.
1
Reducer (2”x1”)
1
2
1” GI pipe (350 mm)
1
3
Reducer (1”x ½”)
1
4
½” Tee
1
5
½” Male nipple (50 mm)
2
6
½” Male nipple (150 mm)
1
7
½” wheel valve-10 kg/cm
2
(Zalota/Hawa)
1
8
½” socket (GI)
1
9
VW sensor
1
10
Adopter
1
11
Cable gland NG 16
1
12
Cable joint holder
1
The uplift pressure meter helps to accurately measure the
uplift pressure at various locations in the foundation of the
dam. Sharp increase in uplift pressure is interpreted as
failure of the foundation grouting or improper drainage sys-
tem. Being surface mounted, it is easy to install and re-
quires no special orientation.
NOTE:
The ½” Tee (sl. # 4) may be repositioned if it is convenient to install the sensor horizontally.
Figure 3.1
