## How to Easily Understand the Torsion Correction Function of ADM?

Release date：2021-01-22 Author： Visitors：2022

ADM’s torsion correction function seems a little difficult to understand for some new clients, so in this article, we use a simple experiment to explain how does the torsion correction function of ADM work and its significance in real project.

**1.Why does the inclinometer casing have torsion?**

There are many reasons for torsion of inclinometer casing, mainly including three aspects.

(1) The material and producing technology of inclinometer casing. If the material is not stable, with the increase of time and external pressure, inclinometer casing may have torsion. It is also possible that the groove of the inclinometer casing twist when the inclinometer is produced, because of the producing ability.

(2) The underground geological environment is complex, and the force of inclinometer casing in the hole is uneven. Then it leads to the torsion.

(3) During the installation, it has torsion when drop down the inclinometer casing.

**2.What’s the influence of torsion on measurement data?**

Bind ADM to a vertical pole and put ADM against the wall, it has an angle between ADM and gravity. We can think now ADM is monitoring a slope. The mark line towards to wall.

From the observation chart, we can know that, before torsion the observation data is very stable. And I will compare 4 parameters to show the change after torsion happens.

__(1)X absolute value before torsion.__

The picture in bellow shows the X absolute coordinates in 5 minutes. (X direction is same as mark-line direction)

__(2)Deformation value of X and Y before torsion__

Next Picture shows the deformation value of X and Y, we can see that now all the deformation value is within 1.5mm.

__(3)Node 220086 deformation value before torsion.__

This 2m length ADMS has 4 nodes totally, 220086 is on the top. We can see that 220086’s deformation value is within 1.5mm.

(4)Now I torse ADM 180 degree, the mark line now towards to the opposite direction.

__(5)X absolute value after torsion. __

We can see that after torsion, X’s absolute value is negative value before torsion.

__(6)Deformation value of X and Y after torsion. __

We can see that now the deformation value of X is almost to 1.8M, the deformation value of Y is almost to 0.5M. It’s a very big value.

__(7)Node 220086 deformation value after torsion. __

We can see that 220086’s deformation value gets bigger suddenly, it’s abnormal.

**3.How does ADM correct the influence on measurement data?**

For ADM monitoring system, it just takes 3 easy steps, then you will correct the torsion data and save it.

(1)Select the moment before torsion happened.

(2)Select the moment after torsion finished.

(3)Then Click “Shift Correction”

(4)You will see all data is normal now. The deformation value of X is within 1mm, the deformation value of Y is within 3mm.

From this test, we can see that the torsion of inclinometer casing has a big effect on the measurement data. I just torse the ADM 180 degree. The degree between gravity and ADMS doesn’t change. But the deformation value has a big change. So the torsion correction is necessary in horizontal deformation monitoring.