New Classificaton and Hydraulic Property Testing for Wet Unsaturated Fine-Grained Soils

Abstract

This paper summarizes research study conducted and has two parts. The first part, classifies fine-grained soils with a new method (USCSM) using Laser Diffraction Method to distinguish within fine particle sizes. The second part, determines hydraulic conductivity (k) and volumetric water content (vwc) of 3 selected unsaturated undisturbed soils with a new hydraulic property tester “Hyprop test”, using the evaporation method. Results showed that under atmospheric (ie. zero pressure) conditions, matric suction (MS) increases with time upto a maximum value then decreases, when cavitation into soil sample or the measurement system at the air entry value (AEV).Reaching time for the maximum matric suction (MMS) increases with decreasing plasticity index (PI) and colloid content (c). MMS increases with PI, c, while increasing matric suction (MS) decreases hydraulic conductivity (k) and c. Also, k at the MMS decreases with increasing PI and c

Keywords

• Unified Soil Classification System-Modified (USCSM), unsaturated fine-grained soils, inorganic clay-colloids, soil hydraulic properties, water-retention, hydraulic conductivity, matric suction, laser diffraction method