Analyzing inclinometer founded in unstable layer

[bns3v]

I am looking for a reference/guidance on how to analyze the following situation.

A series of inclinometers were installed in a landfill, and because of limitations/specification from the client, the casings were not allowed to puncture the lower liner and therefore are not founded in a stable layer (i.e. the whole casing is "floating" in the waste cell). We have performed monthly readings on the casings, and also obtained monthly location survey data for the top of the casing.

The inclinometer manufacturer's software (DMMwin and DigiPro), do not appear to be able to directly analyze this situation. My conceptual analysis method is summarized below; i'm hoping one of the eng-tips gurus will be able to direct me to a resource to make sure i am thinking about it correctly.

- Take the displacement of the top of the casing from the location survey and convert that into movement along each of the casing's axes. I'm not worrying about the effect of settlement yet.

- At each reading depth with the probe, find the difference of the deviation at the current and initial casing measurements, which equates to the incremental displacement at that depth.

- using the location survey data as an offset at the top of the casing, sum the displacements from the top down to determine the cumulative movement of the casing.

 

[Ron]

I think your approach is valid. Have used similar to plot expansive base/subbase materials for pavement. Make sure your measurements are as accurate as possible, since you will be measuring (likely) small increments.