Conference Agenda

<p>This paper presents a case study of a geomembrane liner design in a mining area for con-taminant waste disposal. The presented study involves the need to store steel slag on soft soil foundation that presents a low bearing capacity. The stored material is granular con-taminant material with high permeability and high density. Thus, it was necessary to carry out a stress-strain study on a Finite Element Model, followed by an empirical-analytical verification to assess the feasibility of the waste pile construction. The study predicted a maximum strain of 12%, resulting on maximum displacements of 1.4 m. An implementa-tion of plastic geomembranes was proposed considering the need to promote a flow barri-er faced to the increasing applications bias of geosynthetics in mining industry. Further-more, based on the foundation consolidation process under the steel slag waste pile, Line-ar Low-Density Polyethylene was considered as required by the large expected strains. </p>

<p>Waterproofing the support pad for a large mining heap leach pile is a demanding application since the geomembrane used for this purpose will be subject to the large puncture stress imposed by the pile and it must provide an adequate interface friction angle to secure the stability of the pile, particularly in countries with high seismic activity, and it must be able to withstand the action of the chemicals used for the ore leaching process.</p>

<p>Normal practice in Latin America for the waterproofing of heap leach pads involve the use of polymeric membranes (either HDPE or LLDPE) normally coupled with a medium-weight geotextile to protect the liner from puncturing.</p>

<p>Use of a bituminous geomembrane (BGM) for this application is conceptually appealing to the mining industry since it provides the waterproofing with a single geosynthetic (as opposed to the multiple layers in the usual solution) as well as the elimination of an additional interface (polymeric membrane against geotextile) that may have an effect in the static and dynamic stability of the heap leach pile.</p>

<p>The above lead a large copper mine in Chile to team with a BGM manufacturer to develop a test program to determine the puncture resistance of the BGM sandwiched between the ore and the support soil as well as the interface friction angles between the ore and the BGM and between the BGM and the support soil. This paper will describe the test program as well as the results obtained and their significance for the design of the heap leach pad.</p>

<p>Geosynthetic materials and, more specifically, drainage geocomposites are now widely used for water drainage and gas collection in applications as varied as water drainage and gas collection on final landfill covers, leachate collection in landfill cells, sub-slab depressurization system under buildings, groundwater drainage under embankments, etc.<br />The design methods used are based on the in-plane flow capacity of the geocomposites, which is determined by laboratory tests on a 250-300 mm long product sample. The fluid is injected into the thickness of the product and this drainage capacity is interpolated for actual lengths of several tens of meters.<br />This paper presents the development of hydraulic design software for multi-linear drainage geocomposites, based on laboratory characterizations of the geocomposite and validation with full-scale tests. The software gives a 3D model of the hydraulic curves in the geocomposite depending on the application for which the geocomposite is used, and the fluid to be drained (water, landfill gas, methane, air, etc.). Design examples using the software will also be given.</p>

<p>In Ukraine, loess soils are distributed mainly in the steppe and forest-steppe, where it is the maternal species for black earth. Loess soils are 65-70% of the territory and mostly on floodplain and watershed river terraces.</p>

<p>There is a huge problem with these soils in their behavior in case of waterlogging. It leads to changes in their physical and mechanical properties.</p>

<p>The territory of the airport in Dnipro city is located on the watershed of the two big rivers.</p>

<p>At this object, loess soils have a predominantly solid and semi-solid consistency with small layers of the surface of refractory consistency to a great depth (up to 30 m). Fortunately, there is no groundwater.</p>

<p>It was decided to protect loess soils from water and strengthen airfield pavement with geosynthetic materials.</p>

<p>To ensure the stability of the embankment base, the upper soil layers with minimal bearing capacity must be withdrawn at depth from 1.00 to 1.5 m. To ensure waterproofing and achieve the design value of the bed coefficient on the surface in 74 MN / m³ under the designed airfield pavement is arranged a layer of stabilized soil and an additional layer of bentonite mats with pH fluctuations resistant.</p>

<p>To separate the concrete layers, use non-woven polypropylene thermally reinforced geotextile with a tensile strength of 40 kN /m, CBR 7 kN, and mass per unit area of 400 g/m².</p>

<p>The paper presents the results of calculations of the design of the aerodrome pavement by the finite element method.</p>

<p>It provides a rationale decision for the design and comparative analysis with other structures.</p>

<p>This design provides reliable operation of airfield pavement of airports, arranged on weak and sedentary soils, throughout all their service life.</p>

<p>This paper discusses the pavement design methods used for the applications of geosynthetics. Geosynthetics are used for filtrations, separation, stabilization, drainage and reinforcement of the pavement base course and subgrade layers. Different agencies and organizations use different design approaches for geosynthetics in pavements and there is no unified design methodology that is used nationally. Four design methods were selected for the purpose of this study. These methods are the ones used by California Department of Transportation (Caltrans), New York State Department of Transportation (NYSDOT), US Army Corps of Engineers, and American Association of State Highway and Transportation (AASHTO). The focus is to analyze the design methodologies for drainage and reinforcement. The four methods are used to design a pavement section and the resulting pavement layer thickness and the geosynthetics characteristics were compared. The results for drainage indicated that geotextiles with different Apparent Opening Size (AOS) are obtained by each method with AASHTO method seems to be less conservative to clogging potential. The reinforcing effect is not uniformly recognized by the design methods investigated. Caltrans design method seems to account for the full reinforcing potential of the geogrids for subgrades with R-Value less than 20. NYSDOT does not account for the reinforcing effect of the geosynthetics. The Army Corps identifies a range of pavement thickness over which the reinforcing effect is more pronounced. The proposed modified AASHTO method also specifies a range of pavement thickness for the reinforcing effect of the geosynthetics to be realized although it is a different range from the one identified for the Army Corps of Engineers.</p>

<p>As a common practice, working platforms have to be constructed on weak soils (e.g. clay or peat), for the construction of windmill parks. Such working platforms have to meet stringent requirements in terms of load bearing capacity and deformations. In many cases, working platforms have to be constructed in a short time period, where the loading phase is very limited in time. Accordingly, preloading and consolidation phases are often avoided due to the time and cost restrictions. Often the load intensity and distributions from the cranes are not known, especially during the crane operation in different positions. If a working platform fails, the costs are usually high and in the worst case, this can even cause fatalities.</p>

<p>In the literature, different design approaches are published such as BRE BR470 and CIRIA SP 123 among many others. Nevertheless, several researches are still being conducted on this topic.</p>

<p>This paper will review the possible failure mechanism in various conditions and compare the different published design approaches, which in most cases contain some empirical parameters. After a discussion on the limitation and drawbacks of each of these design approaches, the essential criteria for a proper design of working platforms that accounts for all probable modes of the failure in different situations will be discussed.</p>

<p>The paper will describe how bituminous geomembranes (BGMs) are designed in innovative ways to solve engineering challenges on mining sites in extreme environmental conditions and to provide environmental protection.</p>

<p>The design of BGMs in mine tailings facilities and environmentally sensitive mine waste capping will be focused on, and the technical challenges facing these projects will be discussed in detail. The protection of groundwater by using effective and puncture resistant BGM solutions contribute to creating a resilient planet.</p>

<p>The innovative use of special high friction angle BGMs on the very steep (1V:1.75H) tailings storage embankments of the new large Ravenswood Gold Mine in Australia will be discussed in detail. This mine is under construction in 2021.</p>

<p>BGMs are multi-layered composite geomembranes with each of the components providing a technical benefit on the mining site. These technical advantages include: Extreme puncture resistance, which allows rapid deployment on rougher subgrades; Excellent resistance to wind uplift due to their high surface mass and this means that installation can continue in winds up to 40km/h. Elastomeric BGMs also retain their flexibility in extremely cold conditions and can be installed and welded down to -25 deg C. This means that elastomeric BGMs are often used in the extreme mining conditions of Siberia, northern Canada and the high altitudes of the Andes mountains in South America. BGMs have a very low coefficient of thermal expansion and do not wrinkle with changes in temperature like other polymeric membranes do and this is particularly useful in high heat projects in Australia. This provides a more secure project in the long run, with less risk of wrinkle-induced cracks and failures.</p>

<p>In summary, the paper describes how the technical attributes of the BGM’s composite structure provides a wide range of practical on-site solutions for challenging mining applications and environmental protection.</p>

<p>Geosynthetic clay liners have gained widespread popularity as a substitute for difficult to build compacted clay liners in many applications. A geosynthetic clay liner (GCL), also known as geosynthetic clay barrier (GBR-C) or bentonite mat, is a factory produced clay barrier which mostly consists of two geotextile layers with an intermediate sealing layer of sodium bentonite. GCLs are typically used in all barrier applications, such as landfill caps and base seals - artificial, retention or storage ponds - environmental protection - dams. levees, dykes - under roads, railways, airports. It is important that every GCL must be properly designed for the selected purpose. The GCL requirements must be fit to the anticipated field conditions, mechanical and hydraulic conditions (e.g. permeability), chemical effects from surrounding soils or liquids and shear strength parameters. A main consideration is also the lifetime of the project, so that the durability aspect is also of major importance.</p>

<p>This paper will present key design criteria that are necessary for a proper design and also cover the calculation of leakage rates and shear stability. Other factors, such as the effect of confining stress, influence of freeze/ thaw or dry/wet cycles and influence of chemicals will also be addressed. Finally, the paper will evaluate current well known specification recommendations, such as GRI-GCL-3 and make recommendations for improvements.</p>

<p>Over the past 40 years, the advantages in utilizing geosynthetic barriers versus traditional barrier materials have been well documented: greater project economy, extended service lives, enhanced environmental protection, greater site safety, etc. Achievements such as conserving water resources and enabling beneficial site reuse (e.g., remediation) have even given geosynthetic engineering a level of social importance. As such, the use of geosynthetic barriers has increasingly been required. This is especially true in modern waste management cell design, a barrier application that has been so successful it has influenced the design and specification of geosynthetics into mining, water and wastewater, and industrial applications. However, there are regions and applications in which the use of these barrier technologies should be more widely adopted.</p>

<p>The IGS TC-Barrier is collecting since years regulations and guidelines and will inform about the current status.</p>

<p>This paper highlights an overview of applications where geosynthetic barriers are used and where regulation or recommendations are available and describe selected regulations where geosynthetic barriers are used and also show on a few examples the difference of these and classify them.</p>