Geotextiles and Geomembranes最新文献

The transport of perfluorooctanoic acid (PFOA) through the base of a municipal solid waste landfill lined by a single or double composite liner system underlain by an aquifer is examined. Experiments conducted to obtain permeation coefficients for PFOA (and other PFAS) through HDPE and a GCL at different stress levels are described and the results presented. Experimentally derived interface transmissivity and GCL hydraulic conductivity permeated by a PFAS solution are presented. The experimentally derived parameters for PFOA are then used together with finite element software to model diffusive and diffusive-advective transport of PFOA through holed wrinkles from a landfill. The peak concentrations of PFOA in the modelled aquifer are reported and compared to the maximum allowable drinking water regulations for PFOA in different jurisdictions. A sensitivity analysis is performed to assess the effect of different parameters on the degree of contamination of the aquifer. With no holes in the geomembrane (pure diffusive transport), all regulatory limits are met for both single and double-lined barrier systems. The amount of leakage through holed wrinkles required for PFOA to exceed regulatory limits varies depending on the initial concentration of PFOA and jurisdictional allowable limits. Most results showed that the single composite liner barrier system examined is unlikely to be sufficient to contain PFOA to an acceptable level. The double liner system is more likely to meet regulatory requirements if most of the leakage through the primary is collected.

This paper presents an upgraded nonlinear creep consolidation model for VDI soft ground, incorporating a modified UH relation to capture soil creep deformation. Key novelties also include considering linear construction loads, TDP boundary conditions, and Swartzendruber's flow in the small strain consolidation domain. The system was solved using the implicit finite difference method, and numerical solutions were rigorously validated. A parametric analysis reveals that soil viscosity causes abnormal EPP increases under poor drainage conditions during early consolidation. Meanwhile, neglecting the time effect of the secondary consolidation coefficient delayed the overall EPP dissipation process and overestimated the settlement during the middle and late consolidation stages. Furthermore, TDP boundaries, Swartzendruber's flow, and construction processes significantly influence the creep consolidation process but not the final settlement. These findings offer fresh insights into the nonlinear creep consolidation of VDI soft ground, advancing the field.

In this study, the microstructural characteristics of geotextile envelopes were investigated via two-dimensional (2D) and three-dimensional (3D) image analysis. A pore network model was constructed to predict the hydraulic properties of the geotextile envelopes. Based on image analysis, the representative domain size of the geotextile envelopes was estimated and was further confirmed by pore network modeling. The results showed that while nonuniformity existed in geotextile envelopes, no noticeable difference was observed in porosity among samples of different sizes. The porosity derived from 3D image analysis was much closer to the theoretical value, with relative error less than 12%. The fibers of the geotextile envelopes were mainly distributed in the in-plane direction and were nearly uniform. The prediction of the permeability coefficient was optimal when hybrid cones and cylinders were considered as the geometric shapes and when the equivalent diameter, inscribed diameter, and total length were used as the geometric properties of the extracted pore network. The capillary pressure curves matched experimental values more closely when using the equivalent diameter for throat diameter. The representative domain size of geotextile envelopes was at least 3500 μm, but no meaningful length could be found along the through-plane direction.

This study repurposed discarded carbon fiber fabric by mechanically cutting it into short-cut carbon fibers and utilized these fibers in electro-osmosis experiments with varying lengths (5 mm, 10 mm, and 15 mm) and mixing ratios (0.05%, 0.10%, and 0.25%). The results indicated that increasing the length and mixing ratio of recycled carbon fibers effectively reduced the soil resistivity. Furthermore, incorporating an appropriate amount of carbon fibers not only reduced the energy consumption coefficient but also enhanced the electro-osmotic drainage performance. Increasing the length and mixing ratio of carbon fiber also improved the vane shear strength after electro-osmosis consolidation. To promote the application of carbon fiber in electro-osmosis consolidation and to provide support for the development of electro-osmosis consolidation theory and numerical analysis, a resistivity calculation model of carbon fiber-reinforced soil during the electro-osmosis process was developed based on the Ohm's Law and tunneling transmission theory. The model elucidates that during the electro-osmosis process, soil resistivity is influenced by the increase in barrier thickness, which consequently raises the tunneling transmission resistance.