One of the challenging problems in mountainous regions is protecting pipelines from impact load due to the rockfall. Rockfall characteristics and impact loading have been studied by many researchers; however, there is still a lack of large-scale studies to investigate protection of the steel buried pipelines against the impact of rockfall. In this study, a series of large-scale physical models were developed to simulate the performance of steel pipe buried in protective and unprotective installations. The protection system was geotextile-made bags filled with rubber-sand mixtures. During the falling mass penetration, a few different crucial design parameters including the impact force, the vertical deformation and the circumferential strains at the crown and springline were investigated. As a whole using geobags with the proposed configuration could delay the contribution of the buried pipe in stress bearing, provide more flexible interactions between falling mass, trench soil and the buried pipe, successfully detour the vertical stress to the sides of the pipeline, change the deflection mode to a sort of ring deflection, and protect the buried pipe against the impact stress. The results showed that, depending on the rubber content of the mixture in the geobags, the vertical deformation of the buried pipe was considerably reduced between 31 and 62%.

This paper investigates the effect of landfill bottom liner system base length, sideslope inclination, horizontal sideslope length, waste geometry, and waste stiffness on the mobilized geosynthetic interface strength along the base and sideslope for landfill design. Fifty-two landfill cross-section scenarios were numerically simulated to study the influence of these factors on the mobilized interface strength. The mobilized shear strength along the base of the landfill varies from peak to large displacement (LD) strength, while the mobilized shear strength on the sideslope varies from peak to residual depending on the base length, sideslope length, and sideslope inclination. These results suggest the mobilized geosynthetic interface strength along the bottom liner system is site-specific and a function of landfill waste geometry and stiffness. An increase in waste stiffness slightly reduces the interface shear displacement, whereas a decrease in stiffness leads to a significant increase in shear displacement. Specific analysis should be conducted when dealing with waste of extremely low stiffness.

The paper is focused on sustainability assessment of idealized geosynthetic reinforced soil walls constructed with polyester reinforcement layers using the MIVES multi-criteria decision-making methodology. Sustainability assessments cover environmental, economic, and social/functional components. In this study, the influence of different facing element types (precast concrete panels, welded wire mesh, and dry-cast concrete blocks) and different backfill materials (high-quality granular material, recycled concrete aggregate, and locally available soils with medium to low fines content) on sustainability rankings is investigated. Overall, no significant differences are observed between facing alternatives. Sustainability assessment scorings with precast concrete panels are slightly more favorable for lower walls, while dry-cast concrete blocks are slightly more favorable for taller walls. The use of locally available soils proved to be the most economic, environmentally friendly, and overall, the most sustainable alternative amongst the backfill soil options investigated, even when these soils have less mechanical strength. Total cost and global warming potential estimation charts for reinforced soil walls of different heights are provided.

Like other polymeric materials, geotextiles may degrade through oxidation, potentially affecting their performance and lifespan. In certain applications (e.g. mining sites or waste containment systems), geotextiles are used in contaminated or aggressive environments, with possible exposure to metals or metal ions. This work examines how metal ion solutions (cobalt, copper, iron, manganese, nickel and zinc nitrates) influence the oxidation resistance of two polypropylene geotextiles. For this, the materials were exposed in isolation (individual exposures) and in sequence (consecutive exposures) to metal ion solutions (immersion at ≈20°C for 100 days) and oxidation (oven-ageing at 100°C for 28 and 56 days). The effect of the degradation tests was evaluated by tracking changes in the tensile performance of the geotextiles. The results showed that the geotextiles had a relatively high resistance to metal ion solutions and oxidation (individual exposures). Conversely, the consecutive exposures led to very marked changes in tensile behaviour (in most cases, reductions in tensile strength higher than 85%). The oxidation process was highly accelerated by prior exposure of the geotextiles to metal ion solutions, which contaminated them. The catalytic action of metal ions in the oxidation process was identified as the most likely cause of the accelerated degradation.

The unwanted vibrations resulting from man-made activities are very common and can cause damage to the surrounding buildings. Previous studies have suggested single barriers for vibration isolation that require unrealistic depth requirements. To effectively control the vibration-related hazards, a geotechnical seismic isolation strategy of dual shallow barriers has been explored in the present work. Geofoam has been used as a filling material in the barriers. Extensive field studies and numerical simulations have been performed to isolate the continuous harmonic vibrations. The Lazan-type mechanical oscillator has been utilized to generate continuous harmonic vibrations of frequencies ranging from 20 to 45 Hz. A comprehensive numerical investigation has been conducted to screen continuous harmonic vibrations. The barriers were found to eliminate vibrations of higher frequency more effectively compared to low-frequency excitations. The isolation efficiency of EPS15-infilled dual barriers of a normalized depth of 0.31 was noticed to be 45% higher than that of the EPS15-infilled single barrier of a similar depth (where EPS is expanded polystyrene). Furthermore, an optimum depth of 0.5 LR for EPS15-infilled dual barriers was noticed to be sufficient to reach the vibration-limiting criteria of isolation efficiency equal to or greater than 75% (where LR is Rayleigh wavelength).

A numerical–experimental framework is developed to optimise the design of geomembrane specimens for biaxial tensile testing. Specifically, the geometry and adhesive bonding method of specimens are optimised to maximise strain in the central measuring region while reducing premature failure caused by stress concentrations outside this region. Numerical simulations are used to generate stress distribution datasets, and an objective function integrating two metrics—stress concentration and load transfer efficiency—was used to evaluate specimen geometries. Four key geometric parameters are optimised using a derivative-free subdivision method. Specimens are reinforced by adhesive bonding outside the central region, with bonding methods optimised through uniaxial tensile tests to minimise the effect on inherent material properties. Biaxial tensile tests are conducted to validate and compare three promising geometries obtained from numerical optimisation. The final optimal specimen design achieves a peak central strain of 160.2%, significantly exceeding the previous results. This optimised specimen design provides a valuable basis for future studies on geomembrane biaxial tensile testing.

Foundations bearing on uncompacted coarse-grained soil deposits (e.g. aeolian fine sands) can experience excessive settlements under monotonic and cyclic loading conditions. Straightforward strategies for improving their geomechanical behaviour include mass replacement of the uniform fine sand with high-quality soil (typically coarser sand-with-gravel (S-G) material), along with including geosynthetic reinforcement layers, although this approach may prove uneconomical in practice. The present study advocates an alternative approach employing geogrid-reinforced thin dense S-G layers incorporated at discrete depths within the backfilled fine-sand deposit. A comprehensive programme of 1 g testing was performed to investigate the relative performances of fine sand beds incorporating geogrid layers, unreinforced thin dense S-G layers and geogrid-reinforced thin dense S-G layers compared to the plain (fully unreinforced) fine sand bed. A 150-mm dia. footing bearing on the surface of the sand beds was subjected to a combination of static loading followed by 2000 load cycles of different intensities. The experimental results confirmed that compared to the unreinforced/geogrid-reinforced sand beds, the sand beds with geogrid-reinforced dense S-G layers demonstrated superior performance in terms of limiting the cumulative footing settlement. The demonstrated concept could be of practical use in the economic construction of reinforced soil walls, reinforced foundation beds, and so on.

Three blended polyolefin (BPO) geomembranes (GMBs) with nominal thicknesses of 1.0 mm (BzSw10), 1.5 mm (BzSw15), and 2.0 mm (BzS20) were immersed for 9.3 years in highly acidic (L1-pH 0.5) and highly alkaline (L8-pH 13.5) heap leaching solutions, and water (pH 6.5–7.6), at 85, 75, and 65°C. The solutions simulated pregnant liquors from metal recovery processes. BzSw10 and BzSw15 shared the same resin and antioxidant package, while BzS20 had a different formulation. All three comprised around 90% linear low-density polyethylene (LLDPE) and 10% high-density polyethylene (HDPE) resin. Times to antioxidant depletion and nominal tensile failure generally increased from BzSw10 to BzSw15 to BzS20 across all media. Among the solutions, pH 13.5 was the most aggressive, causing faster antioxidant depletion and onset of degradation, followed by water (pH 6.5–7.6) and pH 0.5. In pH 13.5, melt index and break strength initially decreased but later stabilized at low values, reflecting the strong influence of solution chemistry. Compared to a HDPE GMB previously immersed in the same pH 13.5 and pH 0.5 solutions, the BPOs exhibited faster antioxidant depletion but generally outperformed the HDPE in terms of mechanical property degradation, including break strength and stress-crack resistance.

In Surat, India, a total of 15 full-scale test sections were constructed to examine the performance of geosynthetic-reinforced flexible pavement. The impact of different factors, including the types of geosynthetics, their characteristics, and their placement locations, on the in-situ modulus of the pavement layer was assessed through Falling Weight Deflectometer (FWD) testing. The Modulus Improvement Factors (MIF) established from the three-year field study were found between 1.30 and 1.60 for the geocell-reinforcement, and Layer Coefficient Ratios (LCR) were found between 1.27 and 1.40 for the geogrid-reinforcement. FWD testing revealed an increasing trend in average base layer modulus values in February 2021 compared to initial readings from November 2019, indicating improved stiffness due to traffic compaction and reinforcement effects. However, a slight reduction in modulus was observed in July 2022, attributed to seasonal moisture infiltration from pre-monsoon rainfall. Additionally, deflection basin parameters were analyzed to assess the structural benefits of geosynthetic reinforcement.

A new method, direct stress relaxation, was developed, verified and applied to calculate local geomembrane stress from local strain induced by gravel particles. The method utilizes the fading memory concept whereby the deformation path is taken to have a minor effect on stress if strains remain constant for some time before calculating stress. The method requires a geomembrane time-dependent material model, test time and final local strain to calculate stress. The method was tested against, and was in good agreement with, stresses from finite element models simulating physical tests. The new method was applied to analyse the deformed shape of a geomembrane from a physical test with coarse gravel above a geomembrane to examine new insights into local stresses gained from protection layer testing. Local strains were deduced from the deformed shape using thin plate theory and strains were converted to local stress by the direct stress relaxation method. The local stress results showed that different major tensile strain can develop under different major and minor local stresses. The new direct stress relaxation method now provides the ability to calculate local stress in addition to just strain, which may be used to unlock new insights into local stress rupture.