Development of a New Laboratory Method for Water Erosion Tests Based on Transparent Soil Technique

ABSTRACT Laboratory erosion test is one of the most widely used methods for investigating the flow‐driven soil erosion mechanism at small scales. However, since the soil material and running water are opaque, it is difficult to directly observe the real‐time changes of the soil sample (such as the surface topography and mass variations) during the erosion process. Despite the fact that some recently developed techniques [computerised tomography (CT) and magnetic resonance imaging (MRI)] have been used to capture the internal information of materials, the broad application based on radiation scanning in geotechnical engineering is usually difficult, laborious, time‐consuming and economically expensive. The main objective of this study is to develop an efficient method for creating a 3D model of soil samples based on the transparent soil technique. To achieve this goal, the preparation method of a transparent soil–rock mixture was first introduced. Then, specifically, a surface fitting algorithm based on Non‐Uniform Rational B‐Splines (NURBSs) was briefly described and incorporated into the programme to generate the surface of samples. Moreover, the procedure of the 3D construction method, including experimental setup, image acquisition, data processing and model output, was detailed presented. Finally, the 3D reconstruction and visualisation method were verified by applying it to the flow‐driven soil erosion test. Analysis shows that the proposed method provides a reasonably efficient and accurate shape‐reconstruction approach with acceptable error. The reconstruction and visualisation method could provide another feasible way to obtain evolution data in geotechnical tests.