Vertical In-place Inclinometer — Operating Principle & Installation

Vertical In-place Inclinometer system is designed for the monitoring of lateral movement in the soil, slopes, earthworks, structures, etc. Encardio-rite in-place inclinometer system is designed with a series of in-place sensors that are placed inside inclinometer four grooved casing. To use the sensor for monitoring, a group of four grooved access tubes are attached to one another with the help of fixed couplings. This makes it easier to install in a borehole or embed in an earth/rockfill or fixing it to the vertical face of the structure.

One such set of the groove is placed in accordance with the expected direction of the movement, and if that is unknown, in the N-S direction. Inside the inclinometer casing, there are a string of sensors placed in a continuous array to span the movement area. These sensors successfully pick up the tilt measurement in successive segments, leading to accurate monitoring of the change in the inclinometer casing.

Each of the in-place sensors is equipped with pivoted sprung wheels, that are designed to fit perfectly inside the grooves of the inclinometer casing. Length of spacer tubing is used to estimate the distance between each sensor; the length of each segment over which the tilt is monitored.

• Spacer tubing length (mm) = gauge length (mm) — 381 mm
• The outside diameter of spacer tubing = 19 mm

When there is any movement in the ground, it is reflected in the displacement of the inclinometer casing. This further leads to a change in the tilt of in-place sensors. The change in tilt is reflected in the change in the output of the sensors, proportional to the tilt.

The sensors are connected to a data acquisition system for real-time monitoring of lateral movement. Keeping one end of the casing fixed, it is possible to achieve a complete profile of the access tubing by concluding the output from successive sensors. The horizontal displacement at different depths can be determined by comparing the many profiles of the tubing.

Now that we know the working of the sensor, let’s move onto the vertical in-place inclinometer components.

In-place Inclinometer Sensor Components

• The number of sensors is determined by the depth of the borehole and gage length defined by the user.
• Spacer tubing length is decided based on the gage length.
• The placement tube length is determined with the help of the depth at which the first in-place sensor is to be placed from the tip of the borehole.

NOTE: In the following context, an SDI-12 interface is used with the sensor. You can find the horizontal and vertical sensors at Encardio-rite.

| Also Read: Inclinometer: Types, How It Works, & Uses |

Vertical In-place Inclinometer — Preparation before Installation

Civil works

1. The first step is to install the casing as per the User’s Manual which can be found here.
2. The second step is to create a concrete platform in such a manner that the mouth of the inclinometer casing is placed around 25mm below the top of the concrete platform. Further, the inner diameter of the cavity of the top casing should be around 150mm.
3. Once you’re done, place the protective cover over the concrete platform and use the Hilti HLC-M10x80 fasteners provided to mark the location. Now remove the cover, and install the four mounting fasteners on the marked location, which will be used for the mounting of the protective cover.

Pre-installation checks

There are a number of pre-installation checks that need to be carried before starting with the installation procedure.

• One of the first things while installing a vertical in-place inclinometer is to check for any damage or destruction to the cable/connector of the sensors.
• Each Encardio-rite sensor is marked with a serial number and has two cables attached to them. Check that everything is in place.

NOTE: Keep in mind that the bottom wheel assembly is regarded as the reference point when analysing the …[Continue Reading]