Vibratory Extraction of Clay Fines from Subsurface

Abstract

This paper presents results from laboratory investigations on utilizing ultrasonic and subsonic vibrations to facilitate removal of fine clay particles from the subsurface. A sonicator and a laboratory vibrator were used to vibrate mixtures of sand and pure clay minerals as well as a sample of natural soil from New Jersey. In column experiments, particle extraction resulted in an enhancement in the hydraulic conductivity. Effluent slurries from kaolinite mixtures contained more fine particles than those from montmorillonite mixtures. When subsonic vibrations were applied after ultrasonic treatment, additional quantities of fines were extracted. Abrasion and/or fracturing of sand‐ and silt‐sized grains occurred near the vibrating source. The formation of low‐permeability layers because of particle migration and accumulation may have occurred in the experiments. Experiments conducted in 90‐cm‐ and 120‐cm‐diameter tanks showed that the zone of influence of vibrations extended as far as the tank walls. These results suggested that in‐situ implementation of localized vibrations to enhance hydraulic conductivity of clayey soils, and to facilitate controlled mobilization of clay fines and the associated contaminants, may be feasible.