High-density polyethylene (HDPE) geomembrane is often used as an anti-seepage material in domestic and industrial solid waste landfills. To study the interfacial shear strength between the HDPE anti-seepage geomembrane and various solid wastes, we performed direct shear tests on the contact interface between nine types of industrial solid waste or soil (desulfurization gypsum, fly ash, red mud, mercury slag, lead-zinc slag, manganese slag, silica fume, clay and sand) and a geomembrane with a smooth or rough surface in Guizhou Province, China. Friction strength parameters like the interfacial friction angle and the apparent cohesion between the HDPE geomembrane and various solid wastes were measured to analyze the shear strength of the interface between a geomembrane with either a smooth or a rough surface and various solid wastes. The interfacial shear stress between the HDPE geomembrane and the industrial solid waste increased with shear displacement and the slope of the stress-displacement curve decreased gradually. When shear displacement increased to a certain range, the shear stress at the interface remained unchanged. The interfacial shear strength between the geomembrane with a rough surface and the solid waste was higher than for the geomembrane with a smooth surface. Consequentially, the interfacial friction angle for the geomembrane with a rough surface was larger. The geomembrane with a rough surface had a better shear resistance and the shear characteristics fully developed when it was in full contact with the solid waste.
The propagation and coalescence of cracks in fiber-reinforced concretes (FRCs) is the direct cause of instability in many engineering structures. To predict the crack propagation path and failure mode of FRCs, an orthotropic-bond-based peridynamic (PD) model was established in this study. A kernel function reflecting long-range force was introduced, and the fiber bond was used to describe the macroanisotropy of the FRC. The crack propagation process of the FRC plate with flaws was simulated under uniaxial tensile loading. The results showed that under homogeneous conditions, the cracks formed along the centerline of the isotropic concrete propagate in a direction perpendicular to the load. Under anisotropic conditions, the cracks propagate strictly in the direction of the fiber bond. The failure degree of the FRC increases with the increase in heterogeneity. When the shape parameter is 10 and the fiber bond is 0°, the failure mode changes from tensile to shear failure. When the fiber bond is 45°, the FRC changes from a state where outer cracks penetrate the entire specimen to a state where cracks coalesce at the middle. It was found that the improved model can effectively simulate the crack propagation processes of orthotropic FRC materials.
Discontinuous heterogeneous materials, such as rocks and concrete, exhibit
non-Fourier heat conduction. To predict this type of conduction behavior in
discontinuous materials, a bond-based peridynamic heat conduction model
based on the peridynamic theory was derived by introducing the
dual-phase-lag model. The model was verified by the results obtained using
other numerical methods. The Weibull distribution function was introduced to
describe the heterogeneity in the thermal conductivity. The heat conduction
in a plate with two pre-existing cracks under thermal shock was simulated.
The effects of phase lag and heterogeneity were discussed. The results
showed that the heat transfer rate is mainly controlled by the phase lag ?q
of the heat flux. When ?q remains unchanged, the heat transfer rate
increases with the increase in the phase lag ?T of the temperature gradient.
The influence of cracks on the temperature field is mainly reflected in the
area near the crack end. Although the temperature in the local area may be
positively correlated with ?T in the short term, the long-term influence of
the factor becomes increasingly weaker. The proposed method has a wide
application prospect in simulating non-Fourier?s heat conduction in
discontinuous heterogeneous materials.
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