Vibrating Wire Piezometer Installation Procedure in an Earth/Rock fill and Concrete Dam

Piezometer or pore pressure meter is one of the extensively used geotechnical instruments. They are primarily used to measure pore pressure in concrete structures, boreholes, rock fills, soil, etc. However, different types of piezometers find their application in the geotechnical or geo-structural study associated with large civil engineering constructions like tall buildings, dams, underground tunnels etc.

We will be discussing the installation procedure of Piezometers in earth/rockfill dam and concrete dams.

Let’s get started.

Piezometer Installation Procedure in an earth/rockfill dam using Model EPP-30V

The recommended piezometer for such installation is Encardio-rite Model EPP-30V Electron Beam Welded heavy-duty piezometer.

In an earth and rockfill dam, more than one piezometer and sensors are installed at marked elevations and different cross-sections, as shown in the figure below. Here, for example, nine piezometers and three soil pressure meters are installed at an elevation of 438 m.

The reason behind installing a group of piezometer is that the monitoring of readings helps to discover the phreatic line and shows how it moves with time till steady-state conditions are attained.

Also Read: Vibrating Wire Piezometer — Types and Operating Principle

At any cross-section, the dam is allowed to be filled to an elevation of about 0.5–1 m higher from where the piezometers are to be embedded.
The exact position where the piezometers are to be mounted is cautiously marked. To reach the correct required elevation, offset trenches of about 1m X 1m are dug at these positions.

Using a hand shovel, the material around the sensor is placed and pressed down using a light-duty pneumatic or petrol backfill tamper.
The height of the first layer of material shoved over the sensor should be about 250mm, compacted with precision. Using the same method, the sensor should be covered with the material until 500mm of it has been placed.
The 500 mm height permits rubber tire equipment to cross the location. However, if vibratory rollers need to be permitted to the location, the material thickness should be increased to 1m to avoid any discrepancies.

In the case of piezometer installation in a foundation, necessary boring is done to the required depth and installation of piezometer is done following some listed steps which we have discussed in [Installation of piezometer in a borehole]

While installing foundation piezometer in earth/rockfill or concrete dams, it is advised not to have the junction box and route one continuous cable from the sensor to the observation room. During such cases [Continue Reading…]