How to Install Digital Inclinometer in a Diaphragm Wall?
The digital inclinometers determine and measure the lateral movement in and around landslides, unstable slopes, landfills, tunnels, slurry walls, sheet piling, piles, diaphragm walls, and dams.
However, before installing a digital inclinometer, the placing of the ABS casing is the first step. Here’s how the digital inclinometer installation takes place in a diaphragm wall or pile.
Right before you start reading about inclinometer installation in a diaphragm wall, you should also go through:
Digital Inclinometer System: Preparing for Installation
How to Install Digital Inclinometer in a Borehole?
Preparation for inclinometer installation in D-wall
It becomes a little problematic to install inclinometer casing in a diaphragm wall or a pile. The inclinometer casing gets distorted and stressed when firmly tied to a steel structure from bottom to top. The heat of hydration and stresses generated during the concreting process may distort and even crack the casing.
1) The first step is to fix a 150 mm-bore diameter steel guide pipe vertically within the reinforced bar cage. The length of the pipe to be installed should be such that its top remains approximately 0.5 m above the current ground level. The bottom of the guide pipe should be around 0.5 m above the bottom level of the cage and sealed at the bottom with a concrete plug/plastic cap.
2) While the cage is being concreted, you need to make sure that the jointing of tube lengths is waterproof to prevent any grout/concrete from entering into it. Dented or distorted pipes should not be used as this will make installation of inclinometer access tube difficult or even impossible.
3) We recommend installing an auxiliary guide pipe adjacent to the main guide pipe at 1.25 m approximately centre-to-centre distance at critical monitoring locations. This auxiliary pipe can be used in case the main pipe is choked and becomes useless.
4) Weld the guide pipe firmly to the cage. You need to ensure that it remains vertical and is least distorted during lowering of the cage.
5) Concrete cage after covering the mouth of the guide pipe.
6) Flush the guide pipe clean with water and verify depth with the help of a suitable depth measuring device (e.g. a sounding chain) that it is fully open up to the bottom.
7) Before installing the access casing in the guide pipe, ensure that the heat of hydration of mass concrete has dissipated. You can use a temperature probe for this purpose. The temperature should not exceed 40-degree Celsius. The heat of hydration, if present may warp access casing and render installation useless.
| Also Read: Digital Inclinometer System: Introduction & How does it Work
Installation of inclinometer casing in MS casing (D-wall)
1) Lower the casing with bottom cap into the guide pipe, gripping it with the safety clamp secured around 500 mm from the top. Maintain one pair of casing grooves parallel to the direction in which lateral movement is to be measured i.e. perpendicular to the diaphragm wall.
2) Take a casing pre-assembled with a fixed coupling, having a safety clamp secured around 500 mm from its top end and mate it with the pipe, already lowered through the coupling end. Pop-rivet the fixed coupling to the lowered casing at four places.
3) Seal joint with mastic waterproof tape and BOPP tape
4) Remove the safety clamp from first casing and lower jointed casings into the guide pipe. To counteract buoyancy, if required fill casing with [Continue Reading…]
