Installation Planning

Safety Considerations

Any activity, especially within a construction environment, carries safety risks. The risks to health, safety and environment are distinct to each application. A full site-specific risk assessment should be conducted prior to installing any Osprey Measurement Systems equipment.

Some hazards when assembling and installing an In-Place Extensometer are:

• Use of hand tools

• Manual handling

• Pinch points

Tools & Equipment Required

Equipment

• In-Place Extensometer

• Plastic coated GRP rod (6mm)

• Top support

• Bottom support

• GRP rod coupling (where required)

Tools

• 2mm Allen key

• Cable strippers

• Cable cutter

• Wire snips

• Junior hacksaw

• Flat file

• Tape measure

• PVC pipe cutter

• Stanley knife

• Reed switch extensometer probe

• Multimeter

Materials

• Cable ties

Planning the Installation

Installation occurs following the successful installation and commissioning of the magnetic extensometer.

Conduct a Manual Survey

The manual survey of the magnetic extensometer installation should use the base of the extensometer access tube as the reference.

Survey Procedure:

1. Lower the probe to the bottom of the access tube and note its depth

2. The offset between the tape measurements and the tip of the probe should be known

3. Retrieve the probe until it is activated by a magnet.

4. Find the lowermost point at which the probe is activated by the first magnet. Note the depth.

5. Slowly draw the probe up to find the uppermost point at which the probe is activated. Note the depth.

6. Repeat the process for all remaining magnetic targets

7. Calculate the average between the lowermost and uppermost points of the magnetic field to find the centre point.

Top Support or Bottom Support

Bottom Support (Preferred Method)

Provided that the magnetic extensometer is suitably socketed into a competent foundation material such as rock or stiff clay, the IPX can be supported from the bottom.

Advantages:

• Not affected by stresses on the PVC access tube

• Allows for easy extension or shortening of the system without interrupting the existing sensors

Top Support

Top support can be used where:

• The foundation socket is not confirmed

• Applications where subsidence due to tunnelling or undermining is being monitored

Intended Positions for the IPX

Consideration should be given to where the sensors are to be positioned. This will vary depending on factors such as:

• Expected movement

• Whether the installation is bottom or top supported

• Whether telescoping sections are being used

Positioning Guidelines