Influence of suction on the parameters of the Marchetti Dilatometer Test on a compacted residual soil

Abstract

This study had the objective to evaluate the application of the Marchetti Dilatometer Test (DMT) on compacted residual soil, analyzing the influence of suction on the parameters obtained. For this, a sample of residual diabase soil was collected and compacted in the laboratory at its optimum moisture content. Granular matrix suction sensors (GMS) were installed inside the compacted sample to monitor the suction during the experiment. The GMS allowed the monitoring of suction profile variations during the drying of the specimen submitted to ambient conditions. The DMT blade was statically inserted at 6 different points of the specimen surface with measurement of parameters A and B at every 10 cm deep. It was observed that with the increase of suction, there is an increase in both: material index value (I_D) and dilatometric module (E_D), but a reduction in the horizontal stress index (K_D) value. The increase in E_D value and reduction in K_D value indicates that there is an increase in deformability modulus (E) and a decrease in coefficient of at-rest earth pressure (K₀). The DMT correctly detected the trend in variations in geotechnical parameters as a function of variation in soil suction profiles.

Keywords
Site characterization; Marchetti dilatometer test; Compacted residual soil; Unsaturated soils; Soil suction