| The fundamental premise of this research is that transparent synthetic materials with geotechnical properties similar to those of soils can be used to study 3-D deformation and flow problems in natural soils. Transparent soils are made of either silica gel or silica powder and a pore fluid with a matching refractive index. Two families of transparent soils were developed. The first family, made from silica gel, was used to model sands. The second family was made from silica powder to model clays.; An optical system consisting of a laser light, a CCD camera, a frame grabber, and a PC was developed to measure deformations in transparent soil non-intrusively. The model was sliced optically using a laser light sheet. A distinctive speckle pattern was generated by the interaction of the laser light and transparent soil. A 2-D deformation field was obtained from two speckle images by using an image processing technique named adaptive cross-correlation (ACC). ACC is an advanced digital image cross-correlation (DIC) algorithm. ACC utilizes both window sizing and window shifting methods to give a better performance than conventional DIC in the analysis of soil images.; Transparent synthetic soils were found to exhibit geotechnical properties similar to those of natural soils. Comparison of 2-D deformation fields between transparent soil and natural soil showed that the results were comparable in almost every aspect. The advection-dispersion processes were visible in 2-D flow test in transparent soil. All the tests proved that transparent soils can be used for strength, deformation, and pollutant transport in natural soils.; The 3-D deformation fields under a model footing were obtained by combining 2-D deformation fields of multiple cross-sections. The results verified that the developed system and transparent soil are suitable for the study of 3-D deformation problems in natural soils.; The main advantages of the developed methodology are as follows. First, a continuous deformation field was obtained non-intrusively. Second, the developed method can be readily adjusted based on the modeling requirements. Third, the low cost permits its routine application in geotechnical and geo-environmental researches. Finally, transparent synthetic soil is the only material capable in representing a wide range of natural soils, which can be used in simulating complicated geological features. |
