User's Manual
Vibrating Wire Settlement Cell
1. Settlement Cell
VW settlement Cell Model IG-1403 is used to measure settlement in places where standard optical techniques cannot be employed due to inaccessibility. A Settlement Cell is a unique application of the piezometer in which a low capacity piezometer (1, 2 or 3 kg/cm²) is connected to a fluid-filled reservoir through a connecting tube.
The piezometer is embedded at the point where settlement is to be monitored and the reservoir located at a fixed reference location away from the settlement area.
The transducer measures the pressure created in the column of liquid in the tube. The height of the column is equal to the difference in elevation between transducer and reservoir. The downward movement of the piezometer with settlement increases the height of the liquid column and pressure measured by the transducer. This change in pressure is converted to mm of liquid head, which is the resultant settlement with reference to the initial reading.
2. Typical Applications
- Monitoring settlement in embankments, fills, and foundation soil.
- Measuring large settlements under earth dams and soft soils.
- Land reclamation and consolidation monitoring.
3. Outstanding Features
- Robust and sturdy construction.
- Accurate readings.
- Corrosion-resistant option available for coastal applications.
- Provision of thermistor for temperature measurement.
- Provision of gas discharge tube for lightning and surge protection.
- Suitable for remote reading, scanning, and data logging.
- No effect of cable length on the performance of the sensor.
- Provision of vent tube automatically compensates the effect of change in atmospheric pressure.
4. Description:
The settlement system has a fixed assembly contained in a wall-mountable panel located at the fixed reference position. This consists of a cylindrical reservoir having four holes. is connected through a distributor valve to the sensor/sensors while the other one has a level tube which maintains a fixed level of fluid in the reservoir. One top hole is for liquid entry into the reservoir while the other hole at the top is for air. The reservoir must be filled with water till it starts overflowing through the level tube before taking any reading. Caution: Exposure of tubing and reservoir to direct sunlight must be avoided as far as possible as this would create a temperature gradient in the fluid and cause error. A manifold divides the fluid from the reservoir into two tubes per sensor. These tubes take fluid into the sensor through two openings at its bottom. The sensor has a 4 core cable for output along with a vent tube for maintaining uniform atmospheric pressure throughout the system. The sensor is mounted on a settlement plate of dimension 200mm x 200mmx 3mm thk. The cable, vent tube and the two fluid filled tubes all pass through the same trench to go up to the control panel. The cable is connected to the connector provided on the panel and the vent tube terminates into a desiccant chamber. The desiccant chamber is mounted inside the panel and protects the vent tube from getting clogged by moisture or dirt. The chamber is filled with silica gel to absorb moisture and has two apertures to maintain uniform atmospheric pressure. The fluid filled tubes terminate into a manifold through quick fix couplings. The manifold is directly connected to the reservoir. Initially, all the ports of the manifold are closed with plugs.