In geotechnical engineering, bioinspired ideas such as snakeskin-inspired solutions for frictionally anisotropic continuum materials have been receiving increased attention due to their ability to create resilient and efficient geomaterial-continuum interfaces. Several studies have found that snakeskin-inspired continuum surfaces mobilise significant frictional anisotropy with different soils. However, studies on the effect of snakeskin-inspired patterns on other continuum geomaterials, such as rock surfaces, which can have promising applications like friction rock bolts, are rare. This study aims to address this gap by investigating the effect of snakeskin-inspired patterns on the shear behaviour of soft rocks, which is simulated by Plaster of Paris (PoP). For this purpose, snakeskin-inspired continuum surfaces with surface patterns inspired from the ventral scales of a snake with five different scale angles (10 degrees, 13 degrees, 16 degrees, 19 degrees and 22 degrees) were 3D printed with Polylactic Acid (PLA) polymer using a Fused Filament Fabrication (FFF) 3D printer. The interface shear behaviour of these surfaces with PoP was investigated using a customised interface shear testing apparatus under three normal loads: 1000 N, 2000 N and 3000 N. The results of the tests confirm that snakeskin-inspired patterns on continuum material mobilise substantial anisotropic friction and that the interface shear response depends on the shearing direction and the scale angle. The shearing direction significantly affects the peak and post-peak shear behaviour and the strain softening behaviour of the snakeskin-inspired interfaces. The study yields promising results for applying snakeskin-inspired patterns to create rock bolts with direction-dependent friction and enhances the existing knowledge in bioinspired geotechnics.

Solidified soil prefabricated pile (PPSS) is a new type of pile formed by extruding solidified soil with hydraulic equipment. The PPSS includes two parts: precast pile and core pile, which can be used to strengthen soft foundation. To study the deformation characteristics of PPSS under vertical load, the nonlinear mechanical behaviour of the double-contact interface of PPSS is analyzed by using the bond slip model and hyperbolic model. A settlement calculation method is proposed considering the displacement coordination of the doublecontact interfaces, e.g., interface between precast pile and surrounding soil, and interface between core pile and precast pile. The bearing characteristics of the double-contact interfaces are studied by using the numerical results. Based on the numerical results, the effects of elastic modulus ratio, diameter ratio, length and initial cohesion on the deformation characteristics of PPSS are analyzed.

This study compares two 3D nonlinear FE models, 'simplified coupled' and 'uncoupled', to explore 'light' damage in a two-storey masonry building on strip foundations affected by subsidence. Both models employ nonlinear interfaces to simulate soil-structure interaction: the simplified coupled model ties the structure with the soil volume with 'contact interfaces', while the uncoupled model uses 'boundary interfaces' to represent the interaction. The impact of soil volume and settlement shape size is examined. Results indicate consistent damage, displacements, and stresses across both modelling approaches with the smallest soil volume. Differences increase with larger soil volumes: at a distortion of 1/1,000 in hogging, the coupled model shows the damage decreases by 54% when the soil volume is quadrupled. Mesh size is also observed to affect crack initiation but not the overall damage mechanism. In general, coupled models reduce non-convergence and computation time, whereas uncoupled models simplify the analyses by decoupling the problem.

Interactions among microbes, minerals, and organic matter are key controls on carbon, nutrient, and contaminant dynamics in soils and sediments. However, probing these interactions at relevant scales and through time remains an analytical challenge due to both their complex nature and the need for tools permitting nondestructive and real-time analysis at sufficient spatial resolution. Here, we demonstrate the ability and provide analytical recommendations for the submicron-scale characterization of complex mineral-organic microstructures using optical photothermal infrared (O-PTIR) microscopy. Compared to conventional infrared techniques, O-PTIR spectra collected at submicron resolution of environmentally relevant mineral and organic reference compounds demonstrated similar spectral quality and sensitivity. O-PTIR detection sensitivity was greatest for highly crystalline minerals and potentially for low molecular weight organic compounds. Due to photothermal effects, O-PTIR was more sensitive toward organics than minerals compared to conventional IR approaches, even when organics were mineral-bound. Moreover, O-PTIR resolved mineral-bound and unbound organics in a complex mixture at submicron (<500 nm) resolution. Finally, we provide best practices for artifact-free analysis of organic and mineral samples by determining the appropriate laser power using damage thresholds. Our results highlight the potential of O-PTIR microscopy for nondestructive and time-resolved analysis of dynamic microbe-mineral-organic matter interactions in soils and sediments.

The non-biodegradability of Ethylene-Propylene Side-by-Side (ES) fibers has led to significant environmental pollution from waste sanitary products, thereby posing a severe challenge to the environment. Replacing traditional non-biodegradable materials with biodegradable polymeric materials is the most effective method to achieve a green environment. In this study, core-sheath fibers composed of biodegradable poly (butylene adipate-co-terephthalate) (PBAT) as the sheath layer and polylactic acid (PLA) as the core layer were fabricated. The effects of different viscosity ratios and the composite ratios of sheath and core on the structure and performance of the resultant core-sheath fibers were investigated in detail. The results showed that when the PBAT/PLA composite ratio is 50:50 and the viscosity ratio range from 0.8 to 1.43, the PBAT/PLA core-sheath composite fibers exhibit good spinnability and a complete core-sheath structure, with their tensile properties comparable to those of PP/PE core-sheath composite fibers. Further research found that when the viscosity ratio was 1.00 and the PLA component content in the PBAT/PLA composite fibers increased from 40% to 60%, the fibers still maintained good spinnability and a complete core-sheath structure. In addition, when the PBAT/PLA composite ratio was 60:40, after 120 days of biodegradation, its strength retention rate was only 35.2%. The influence of viscosity ratio and composite ratio on the spinnability of PBAT/PLA sheath-core fibers. image

Unsaturated soil-continuum interfaces determine the behavior of structures such as friction piles embedded in unsaturated soil and retaining walls with unsaturated backfill. Developing accurate constitutive models for these interfaces is essential for innovative computational design and analysis in geotechnical engineering. This study presents a rigorous mathematical derivation to quantify the bonding effect at interparticle and pore space contact zones, introducing a bonding variable and a state parameter based on the ratio between current and critical void ratios. The novelty lies in introduction of a hydraulic-mechanical (HM) coupling constitutive model for unsaturated soil-continuum interfaces, incorporating the bonding effect and critical-state concept. Despite the 16 parameters in proposed model, all are methodically calibrated using suction-controlled interface shear tests. Effectiveness of the model is demonstrated through predictions in interface shear tests involving unsaturated Toyoura sand, smooth/rough steel, and published tests with unsaturated Minco silt and steel. The model's applicability is extended to diverse conditions, including structural stiffness, interface thickness, counterface roughness, and drying- wetting (D-W) cycles. This model provides a unified framework for analyzing volume changes and stress-displacement responses in unsaturated soil-continuum interfaces, providing valuable insights for design of pile foundations in unsaturated soils.

Polyethylene has temperature dependent properties. As a thermoplastic material, it softens on heating and hardens on cooling. This behavior affects the contact surface areas of materials made out of polyethylene, such as geomembranes, adjacent to other materials. Interface strength properties depend on the contact area and stress at the interface. Since the soil-geomembrane interfaces are relatively weak and potentially form the critical failure planes, modeling temperature dependent soil-polyethylene contact surfaces is important. A theoretical model to determine soil-polyethylene contact areas was developed during this study and presented in this paper.