On-sample water content measurement for a complete local monitoring in triaxial testing of unsaturated soils

TL;DR

This paper presents a method for local water content measurement in unsaturated soils during triaxial testing, combining resistivity probes with displacement and suction sensors for comprehensive monitoring.

Contribution

It introduces a novel local water content measurement device integrated into a triaxial testing setup, validated with calibration curves and model comparisons for unsaturated soils.

Findings

Resistivity calibration curves show high accuracy and repeatability.

Two models for resistivity-water content relationship are validated.

The method enables comprehensive local monitoring during soil testing.

Abstract

To provide a complete local monitoring of the state of an unsaturated soil sample during triaxial testing, a local water content measurement device was adapted to a triaxial device comprising the measurement of local displacements (Hall effect transducers) and suction (High capacity transducer). Water content was locally monitored by means of a resistivity probe. The water content/resistivity calibration curves of an intact natural unsaturated loess from Northern France extracted by block sampling at two depths (1 and 3.3 m) were carefully determined, showing good accuracy and repeatability. The validity of two models giving the resistivity of unsaturated soils with respect to their water content was examined.