In this study, laboratory aging experiments are conducted to examine the aging effect on the interface shear behavior between soil and geomembrane. In the first stage, the geotechnical index and shear strength parameters of the soils are determined through laboratory experiments. The second stage focuses on examining the shear strength behavior of soil-geomembrane interfaces. The study examines commonly used geomembranes in the world, such as high-density polyethylene and thermoplastic polyolefin. Different synthetic waste leachates prepared in laboratory conditions are used to simulate real field conditions. The aging effects of geomembranes are examined by subjecting them to different pore liquids in the curing pool for 16 months. The surface deformations and roughness of the geomembranes used in the experiments are analyzed using scanning electron microscopy and optical profilometer. The study evaluates the effects of soil properties, pore liquids, and aging on the geomembrane surfaces. Soils with more coarser grains exhibited higher interface friction angles. It has been determined that the interface friction angles were significantly adversely affected by all curing liquids. Acidic mine drainage was found to have the most detrimental effect on the interface friction angles of geomembranes, while coal combustion product leachate caused minimal damage. The results from optical profilometer and scanning electron microscopy analysis aligned with the interface direct shear test results, further supporting the findings from the experiments. The study has shown that the design interface friction resistances are not sufficient for geomembranes exposed to chemicals in the long term. This aspect should be taken into consideration when creating design parameters.
The canal is crucial for water diversion projects, but it is susceptible to frost damage. To address this, a two-layer composite geomembrane lining structure (TLCGLS) was proposed that regulates the interaction between canal lining and frozen soil. Model tests were conducted to investigate its anti-frost heave effectiveness. Considering the interaction among the lining, two-layer composite geomembranes (TLCGs), and frozen soil, a canal frost heave model with heat-water-mechanical coupling was developed. The influence of canal cross- shapes and TLCGs arrangements on anti-frost heave performance and mechanism of TLCGLS were discussed. Results show that TLCGLS reduces uneven frost heave degree and compressive/tensile strains of the lining by 35%, 29%, and 28% respectively. During melting, it rapidly reduces frost heave, tangential deformation, and strain with minimal residual effects. TLCGLS demonstrates strong resetting ability and excellent anti-frost heave performance. It is particular suitable for arc-bottomed trapezoidal canals. However, excessive reduction in friction between TLCGs weakens arching effect of the bottom lining, increasing tensile stress and safety risks. TLCGLS with geomembrane-geotextile contact exhibits superior anti-frost heave performance, mitigating compressive stress by over 50% while meeting design requirements for tensile stress. These findings provide a theoretical basis and technical solution for mitigating frost damage in canals.
The nominal buffer layer combination is evaluated in this paper to control swell and improve the strength property of expansive soils by using geomembrane (G) and various buffer layer materials such as river sand (RS), pond ash (PA) and murram (M). Different combinations of buffer layer, percentage of stabilizing agents (lime, L, and cement, C), and conditions (cured (C) and uncured (UC)) were used to conduct tests. The expansion ratio (ER) was found to be not significantly reduced in combinations with untreated buffer layers when compared to treated buffer layers. ER was further reduced in combinations with geomembrane, demonstrating that geomembrane prevented water movement and prevented Black Cotton (BC) soil from becoming saturated. Three criteria were used to assess the optimal combination: reduction in swell, gain in strength, and feasibility. BC + G + BC3%L + RS (C) and BC + G + M6%L + PA (C) both fit the requirements for construction on expansive soils.
A set of direct shear tests conducted to investigate the effects of sand mean grain size and geomembrane surface roughness on the shear behavior of the sand-geomembrane interface. Four types of sands with different mean grain sizes were used and the interfaces included a smooth geomembrane and four textured ones with different asperity characteristics. The samples were prepared in a direct shear box at five sedimentation angles. The experimental results showed that the peak friction angle of the soil-textured geomembrane interface was dependent on the mean grain size, inherent anisotropy, and surface roughness of the geomembrane. The shear strength of sand-textured geomembranes was two to three times larger than that of the sand-smooth geomembrane interface. The peak and residual friction angles of the sand-smooth geomembrane interface occurred at an orthogonal angle of sedimentation while it happened at higher angles for the sand-textured geomembrane interface. An increase in mean grain size increased the shear strength of the sand-textured geomembrane interface; while a reverse condition occurred for the sand-smooth geomembrane interface. The shear strength occurred at larger horizontal displacement as mean particle size increased and the effect of relative roughness on peak friction angle increased with increase in mean grain size.
Earthquake is one of the most critical hazard that damage buildings all over the world. Earthquake can result in ground shaking, soil liquefaction, damages, or even leads to complete collapse of buildings. So, buildings must be built to withstand the effect of earthquake so as to secure living conditions. Isolation method emerged as one of the efficient techniques for reducing the severe effects of earthquake. This project proposes a promising seismic isolation method by analysing different isolation method. A variety of isolation materials are available in order to reduce the seismic impact on buildings. This study investigated the efficiency of isolation materials such as polyurethane (PU) foam, coir fibre polyester composite, and geomembrane on seismic effect. In order to study the effectiveness of different isolation materials, seismic responses such as maximum roof acceleration, storey displacement, drift, and base shear of G+4 building was analysed using linear analysis by ANSYS software. Thus, this work aimed to propose the best suitable position of the most effective isolation material that reduces the seismic energy transferred. On other hand the use of this isolation method can provide an economic way to reduce the seismic energy transferred.
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.
The interface shear behaviour between the geomembranes and soils was studied. Sand/ bentonite (80/20), crushed sand, river sand, crushed gravel, and river gravel were used in this study. Polyvinyl chlorides were cured in the 0.5 molar saltwater and high-density polyethylene was cured in municipal solid waste leachate for eight months. Direct shear experiments were performed using cured GMs. This study recommends the use of crushed gravel in projects that use polyvinyl chloride and high-density polyethylene. The interface friction angles, which were exposed to the effects of saltwater and municipal solid waste leachate, decreased even after eight months, and this reduction effect should be considered in future projects. When designing projects involving GMs exposed to MSW leachate, particularly in landfills, potential damage over time should be considered, and appropriate design parameters should be selected. Failure to do so can lead to disasters that cause the loss of life and property.
The interface shear behaviour between the geomembranes and soils was studied. Sand/ bentonite (80/20), crushed sand, river sand, crushed gravel, and river gravel were used in this study. Polyvinyl chlorides were cured in the 0.5 molar saltwater and high -density polyethylene was cured in municipal solid waste leachate for eight months. Direct shear experiments were performed using cured GMs. This study recommends the use of crushed gravel in projects that use polyvinyl chloride and high -density polyethylene. The interface friction angles, which were exposed to the effects of saltwater and municipal solid waste leachate, decreased even after eight months, and this reduction effect should be considered in future projects. When designing projects involving GMs exposed to MSW leachate, particularly in landfills, potential damage over time should be considered, and appropriate design parameters should be selected. Failure to do so can lead to disasters that cause the loss of life and property.