Geotechnical Instrumentation 1

[priyainuk2009]

We are constructing Underground Station box using Top-Down sequences.We have reached excavation till Concourse Level & found some anomaly in behavior of Strain Gauges & Load Cells.
We proposed to use steel struts at four consecutive levels to support the excavation pit from time to time against failure & collapse. We found that readings taken on same strut by Strain Gauges & Load Cells are quite different,

Load measured as per Strain Gauges = 438.2T (2 nos Strain Gauges in one strut)
Load measured as per Load Cells = 267.5T

We are unable to understand the difference in values for same location measured by two different instruments. Till date we have installed 3 layers of struts & we are observing same behavior at all layers of struts installed till date.

Thanks
Debasis

 

[Ron]

That would indicate you might have a problem in the strain measurement output device. Are you sure the multipliers in the calculation of the load from the strain gages is correct?