By quantifying the evolution of void ratio in granular soils of different angularity under different normal stress levels adjacent to geomembranes of varying roughness at different stages of shearing, the effect of geomembrane surface roughness on the interface shear mechanisms between granular materials and geomembranes was investigated. The extent of the shear zone thickness at the interfaces between combinations of round/angular particles and smooth/textured geomembrane surfaces were evaluated. For smooth geomembranes, the interface shear strength is developed by sliding and plowing of sand particles, while for textured geomembranes, the strength results from the interlocking and dilation of sand particles. Study on the effect of particle angularity showed that more angular sand particles resulted in larger plowing effects with smooth geomembranes which in turn yielded higher residual friction angles than with rounded to sub-rounded sand. Higher normal stress produced larger plowing effects for a given sand sheared against a smooth geomembrane and reduced the amount of dilation adjacent to textured geomembranes.

Pore scale modeling plays a key role in fluid flow through porous media and associated macroscale constitutive relationships. The polyhedral shape and effective local pore size within granular material microstructure are computed in this study by means of the Euclidean Distance Transform (EDT), a local maxima search (non-maximum suppression), and a segmentation process. Various synthetic packed particles are simulated and employed as comparative models during the computation of pore size distribution (PSD). Reconstructed un-sheared and sheared Ottawa 20–30 sand samples are used to compute PSD for non-trivial and non-spherical models.

The shear strength of particulate material–smooth geomembrane interfaces results predominantly from ploughing and/or sliding of the particles at the interface. The relative contribution of particle sliding and ploughing for a given smooth geomembrane surface is principally a function of relative material hardness, particle angularity, and normal stress. The relative material hardness is ambient temperature dependent since the geomembrane is polymer based. When ploughing occurs at any temperature, the geomembrane surface wears, resulting in altered surface topography and different interface strength. This paper summarises the results of a study that quantified changes in the surface roughness of geomembranes as a function of ambient temperature, normal stress, and particle angularity. Surface roughness measurements were made on both virgin and post-shear smooth geomembrane specimens using a stylus profilometer to quantify the extent of wear resulting from shearing against different counterface materials at different temperatures under different normal stresses. Increased ambient temperature and particle angularity significantly increased the geomembrane surface roughness and provided quantitative insight into the wear mechanisms at granular material–smooth geomembrane interfaces.

Oil spills are one of the most dangerous catastrophes that threaten the oceans. Therefore, detecting and monitoring oil spills by means of remote sensing techniques that provide large-scale assessments is of critical importance to predict, prevent, and clean oil contamination. In this study, the detection of an oil spill using synthetic aperture radar (SAR) imagery is considered. Detection of the oil spill is performed using change detection algorithms between imagery acquired at different times. The specific algorithms used are the correlation coefficient change statistic and the intensity ratio change statistic algorithms. These algorithms and the probabilistic selection of threshold criteria are reviewed and discussed. A recently offered change detection method that depends on generating change maps of two images in a temporal sequence is used. An initial change map is obtained by cumulatively adding sequences in such a manner that common change areas are excluded and uncommon change areas are included. A final change map is obtained by comparing the first and the last images in the temporal sequence. This method requires at least three images to be employed and can be generalized to longer temporal image sequences. The purpose of this approach is to provide a double-check mechanism to the conventional approach and, thus, reduce the probability of false alarm while enhancing change detection. The algorithms are tested on 2010 Gulf of Mexico oil spill imagery. It is shown that the intensity ratio change statistic is a better tool for identification of the changes due to the oil spill compared to the correlation coefficient change statistic. It is also shown that the proposed method can reduce the probability of false alarm.

Using additive manufacturing, computer-assisted models can be rapidly transformed into physical objects. When combined with X-ray imaging, minimally attenuating three-dimensional (3D) printed objects can allow for enhanced insight into soil processes, whether this is through the design of novel testing devices, prototypes or soil surrogates. In this study, this methodology is exploited to investigate the pullout mechanics of bio-inspired anchors. The purpose of this paper is twofold: (1) to demonstrate the value of the union of 3D printing and X-ray computed tomography (CT) technologies; and (2) to evaluate the effect of geometry on the pullout behaviour of plant root-inspired anchor elements. The results of the experimental investigations demonstrate how X-ray CT was used to effectively capture the evolution of soil behaviour during the uplift of three unique 3D printed prototypes. The analysis of the soil response was completed from both a global perspective, through an interpretation of the force–displacement data, and a local perspective, through an image correlation investigation of image sets at sequential displacement increments. The results provide insight into not only the means to design a more optimised anchor element, but also the efficacy of additive manufacturing-assisted X-ray tomography in investigating geotechnical problems.