Replication of geomembrane interfaces using 3d printing (fused deposition modelling) technique

Download
2020-12-22
Uragan, Semkan
Geomembrane – soil interface is a critical consideration in geotechnical engineering applications such as liners and covers in landfills, canals or mine tailing dams. In some cases, lack of sufficient shear strength in these interfaces leads to poor performance, uneconomical design (such as requiring a longer geomembrane in an anchor trench), or may even lead to failure. To eliminate such problems, geometrical features known as asperities (or protrusions) are used on the geomembrane's interfacing faces. These asperities improve the interface shear strength by providing a surface that rakes through the soil rather than slipping. Research involving the optimization of these asperities requires rapid manufacturing of variety of these prototype geomembranes used as samples for interface shear tests. In this study, commercially available HDPE geomembrane samples are compared to 3D printed geomembrane samples in terms of their tensile strength and interface shear characteristics. Firstly, Polypropylene (PP) is selected among other thermoplastics namely PLA, ABS and re-PETG to replicate High Density Poly Ethylene (HDPE) using the data obtained from tensile strength tests. Three soil samples are prepared (containing 0%, 12% and 40% fines content) using Çine sand and non-plastic silt and the index properties for these soil samples are determined. Finally, using the selected prototyping material PP, 3D printed geomembrane samples are compared to HDPE geomembrane samples in interface with these soil samples under 20, 100, and 200 kPa vertical pressures using 60 x 60 mm direct shear tests. Seventy-two direct shear tests are conducted for geomembrane-soil interface shear strength using three different soil mixtures, where each soil sample is prepared at two different densities (loose and dense condition). To simplify the comparison of the similarity between HDPE and FDM-manufactures PP specimens, three comparison indexes are calculated, namely, Asperity Similarity (AS), Smooth Similarity (SS), and Improvement Similarity (IS). As a result of these tests, while FDM-manufactures PP showed promising and comparable results in replication of HDPE samples for all soil mixtures interfaced with geomembranes with asperities, some amount of deviation is observed in soil mixture A, which consists only of sub-angular Çine sand, interfaced with smooth PP geomembrane especially under higher normal loads. This deviation is attributed to the elevated effect of the raking mechanism provided by sub-angular sand coupled with the rougher surface profile that is a known characteristic defect of FDM manufactured parts. Finally, the use of FDM technique in optimization of geomembrane interfaces was recommended and discussed.

Suggestions

Failure analysis of thin spray-on liner coated rock cores
Öztürk, Hasan (2017-09-01)
Thin spray-on liners (TSLs) are surface support materials used in mining and civil engineering projects since 1990s with a wide ranging area of application from bolt/mesh support replacement to pillar reinforcement systems. This study presents the investigation of pillar reinforcement capacity of the TSL coated andesite rock core by compression test to mimic pillar reinforcement effect. The uniaxial compressive strength (UCS), modulus of elasticity (E), and energy absorbance capacity of uncoated and 5 mm co...
Performance Evaluation of Internal Drains of Earthen Dams
Çalamak, Melih; Yanmaz, Ali Melih (American Society of Civil Engineers (ASCE), 2018-12-01)
Seepage is always expected in earthen dams because they are made of porous materials. However, it should be always under control and its amount and pore-water pressures should be kept below acceptable limits. This can be satisfied by installing internal drains. This study reviews the characteristics of blanket, chimney, and toe drains and assesses their suitability and effectiveness for various material types and geometric characteristics in separate cases. Numerical simulations are conducted for steady-sta...
Hydro-mechanical behavior of unsaturated specimens isotropically reconstituted from slurry and compacted specimens
Ahmadi Naghadeh, Reza; Toker, Nabi Kartal; Department of Civil Engineering (2016)
Response of unsaturated soils constitutes an important consideration for many problems in geotechnical engineering. The main objective of this study is to understand coupling hydro-mechanical behavior of the unsaturated reconstituted specimens from slurry and moist-tamped compacted specimen, and to develop practical and cost-effective testing equipment and procedure. The innovations that will be put forth by this study will make the unsaturated soil mechanics more accessible and appealing to those practical...
Numerical reservoir simulation of Alaşehir geothermal field
Aydın, Hakkı; Akın, Serhat (null; 2020-02-10)
Use of a comprehensive reservoir simulation is essential for an effective geothermal reservoir management. TOUGH2 has become a widely used simulator for this purpose. In this study, one of the most exploited geothermal fields in Turkey, Alaşehir geothermal field has been modeled by using TOUGH2 reservoir simulator. The study includes more than 100 wells, which are operated by 7 different developers. The total installed capacity of geothermal power plants in the field is 212 MWe, but additional capacity (98 ...
Performance evaluation of landfills with the HELP (hydrologic evaluation of landfill performance) model: Izmit case study
Yalcin, F; Demirer, Göksel Niyazi (2002-10-01)
Landfilling is the most economical and commonly used final disposal method of municipal solid and hazardous wastes. Leachate, which is the inevitable output of the landfills, may cause serious pollution problems if not properly handled. In this study, the hydrologic evaluation of landfill performance (HELP) model was used to examine the performance of the hazardous waste lot (HWL) of Izmit Industrial and Domestic Solid Waste Sanitary Landfill for three different cases. These cases were the (1) existing desi...
Citation Formats
S. Uragan, “Replication of geomembrane interfaces using 3d printing (fused deposition modelling) technique,” M.S. - Master of Science, Middle East Technical University, 2020.