The electronics units are sealed boxes fitted with desiccators. These absorb the small amount of moisture that, despite the sealing, eventually penetrates the units.
If the windows of the desiccators show pink then they must be changed. Spares are supplied, so fit the spare and dry the old desiccator.
(Note: This recipe is written for an HPD95 but the techniques described apply to transducers in all our instruments)
There are a number of strain gauged transducers in the probe. Occasionally the output of a transducer needs to be nulled, that is, set to a particular output for a given state. This may be because a transducer has been replaced, or because a gradual change in output over time has taken the circuit beyond an acceptable limit.
(Note: This is written for a 95HPD but the techniques apply to all our instruments)
There are a number of strain gauged transducers in the probe. Occasionally the output of a transducer needs to be nulled, that is, set to a particular output for a given state. This may be because a transducer has been replaced, or because a gradual change in output over time has taken the circuit beyond an acceptable limit.
This technical reference document provides examples of pressuremeter tests from a range of materials with illustrations of how engineering parameters can be derived.
CASE A.
Analysis of a self bored pressuremeter test in London Clay
The most straightforward test to analyse is an undrained cavity expansion and contraction in clay, where a self boring pressuremeter has been used. The insertion disturbance is likely to be small and the undrained path means it is easy to calculate radial and circumferential stresses and strains directly from the displacement and pressure measurements made by the instrument. There are a number of analyses that can be applied; what is described here is one approach. The test itself was over water so depth is referred to bed level.
