Correction of output from an internal load cell in a high-pressure triaxial deformation apparatus without a split-piston

Abstract

Internal load cells can be used to measure the axial load applied to a sample during a triaxial ex- periment precisely, which is key to obtaining reliable mechanical data. However, the output from an internal load cell contains an offset, which is a function of the confining pressure, pore pressure, and temperature. For an apparatus without a split-piston, the sample column has a non-zero axial load supported by O-rings even before a hit-point. Thus, a simple zero setting be- fore the hit-point would cause an error in the measured axial load. In this technical note, we present a method that can be used to estimate the offset and correct the output by using outputs from both internal and exter- nal load cells. This method does not require additional experimentation.