Displacement field around an open-tube sampling

Abstract

Soil sampling involves pre-drilling, and penetration and extraction of the sampler tube which inevitably alter soil texture and properties from its in-situ state. The phenomenon is known as sample disturbance. This paper presents an experimental investigation showing the disturbance during the penetration of a sampling tube into a lightly overconsolidated kaolin clay in a 1-g calibration chamber. Equipped with a transparent Perspex window in the front panel with colored flock material spread on the clay surface, digital images were captured continuously during the installation of a half-sampler next to the window. The techniques of close-range photogrammetry and Particle Image Velocimetry (PIV) analysis are used to evaluate the displacement fields around the sampler during its advancement. The experimental evidence provides useful references for detail understanding the sampling disturbance inside and outside the sampler during penetration, which helps to further develop and validate analytical or numerical solutions for this problem.