Use of a three-dimensional scanner for shrinkage curve tests

Abstract

A procedure is proposed for conducting shrinkage limit tests using a three-dimensional (3D) scanner. Shrinkage limit tests were conducted on 27 different soils of varying plasticity. In this study only eight of the shrinkage curves were determined using 3D scanning techniques, while the remaining 19 were taken from literature. An individual specimen was scanned between 30 and 50 times to produce a high-resolution shrinkage curve. Shrinkage curves for each material were obtained by curve fitting a shrinkage model to the measured dataset. The primary intent of the research was to relate the shrinkage curve equation to the plasticity of a given soil. Using linear regression analysis, an empirical correlation was developed to reasonably relate parameter csh from the shrinkage model to the ratio of the plastic and liquid limits. The shrinkage curves produced based on the model have an average difference of ∼1.2% in terms of measured void ratio and predicted void ratio. The method was demonstrated to be robust for materials of low, medium, and high plasticity. The proposed methodology also presents a means of estimating a shrinkage curve in its entirety based solely on the volume of an air-dried sample, the specific gravity, and Atterberg limits of the specimen. This effectively reduces the amount of work needed to derive the shrinkage curve and could potentially reduce the time for a shrinkage limit test by half or more.

State of practice for use of the soil-water characteristic curve (SWCC) in geotechnical engineering

“…The research literature shows that a number of studies have been undertaken on the shrinkage curve behaviour of soils (Ho 1988;Marinho 1994Marinho ,2017Tripathy et al 2002). A further fitting study of shrinkage curve test results was recently undertaken by Wong et al (2018). The c sh fitting parameter was found to vary with the plasticity of the soil and a close correlation was found with the plasticity ratio, PL/LL as shown in Figure 9.…”

“…Effect of varying csh on the shrinkage curve. Relationship of csh to the plasticity ratio (i.e., PL/LL) (afterWong et al, 2018). Shrinkage curve for Regina clay.…”

Soil-water characteristic curves - Determination, estimation and application

“…By plotting the void ratio instead of volume of the soil specimen with gravimetric water content gives the more familiar shrinkage curve. Advances have been made in the measurement of shrinkage curves using laser triangulation (Jain et al 2015), photogrammetry (Upreti and Leong, 2017;Li and Zhang, 2018), and 3D scanner (Wong et al 2018). Essentially these measurements enable 3D models of the soil specimen as it dries to be constructed for volume determination.…”

Soil Shrinkage Characterization of Low Plasticity Soil Using Digital Image Analysis Process

“…The non-contact measurement techniques includes the use of displacement transducers [15], laser sensors [16], digital imaging with high-resolution cameras [17,18] particle image velocimetry (PIV) technique [19] and photogrammetric technique with pin-hole cameras [20,21]. All these techniques appear to be more sophisticated and necessitate the knowledge of coding, 3D modeling, and simultaneous use of multiple softwares to process the 3D models.…”