An X-ray imaging facility to improve geosynthetic landfill liner materials

用于改进土工合成垃圾填埋场衬垫材料的 X 射线成像设备

• 批准号: 440485-2013
• 负责人: Take, WilliamAndrew
• 金额: $ 7.12万
• 依托单位: Queen's University
• 依托单位国家: 加拿大
• 项目类别: Research Tools and Instruments - Category 1 (<$150,000)
• 财政年份: 2012
• 资助国家: 加拿大
• 起止时间: 2012-01-01 至 2013-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=508884
• 关键词: ray; imaging; facility; improve; geosynthetic

The purpose of a landfill liner is to act as a hydraulic barrier between leachate produced in a landfill and our groundwater drinking water supply. A composite landfill liner typically consists of two barrier layers - the first a thin (e.g. 1.5 mm thick) high density polyethylene (HDPE) geomembrane (GM), and the second a 10 mm thick geosynthetic clay liner (GCL). This second layer is needed because the top GM layer will realistically always contain accidental punctures created during the construction process. A GCL consists of a layer of exceptionally low permeability clay (bentonite) that is bonded to one or more geosynthetics (e.g., sandwiched between two geotextiles using needle-punched fibres, or stitch bonding, or to a geomembrane using an adhesive). Because the GCL contains clay, it will shrink and swell with the loss and uptake of moisture. On the negative side, this means that if the GCL dries out, it will shrink and perhaps even crack. A cracked landfill liner is obviously not an effective barrier to either landfill gas (e.g. methane) or fluid. On the positive side, the potential for this clay to experience large amounts of swelling can create a situation where these cracks can be swollen shut resulting in the barrier self-healing and regaining its excellent hydraulic properties. However, this swelling is only possible in certain circumstances depending on the chemistry of the fluid that tries to resaturate the barrier (i.e. it will self-heal if permeated with water, but some components of landfill leachate or pore fluid from chemically complex foundation soils may supress this ability). Fundamental research is therefore needed to understand the complex mechanisms of cracking and self-healing in these materials. However, because the bentonite clay inside the GCL is fabric encased, these cracks are hidden from view and can only be seen using X-rays. The purpose of this grant is to seek funding for an X-ray imaging facility so that a team of 5 MSc. students and 4 Ph.D. students can to perform non-destructive testing (NDT) on GCL liner (and other) materials to quantify the risk of GCL damage under a wide range of field exposure conditions and aid in the on-going collaboration with a Canadian GCL manufacturer to develop new more damage-resistant GCL products.

堆填区衬垫的作用是在堆填区产生的渗滤液和我们的地下水饮用水供应之间充当水力屏障。复合填埋衬垫通常由两个屏障层组成-第一个是薄（例如1.5毫米厚）高密度聚乙烯（HDPE）土工膜（GM），第二个是10毫米厚的土工合成粘土衬垫（GCL）。这第二层是必需的，因为最上面的GM层实际上总是包含在施工过程中产生的意外穿孔。GCL由一层渗透性极低的粘土（膨润土）组成，它与一种或多种土工合成材料粘合在一起（例如，用针刺纤维夹在两种土工织物之间，或用粘合剂粘合在土工膜上）。因为GCL含有粘土，它会随着水分的流失和吸收而收缩和膨胀。消极的一面是，这意味着如果GCL变干，它将收缩，甚至可能破裂。破裂的垃圾填埋衬垫显然不是垃圾填埋气体（如甲烷）或流体的有效屏障。从积极的方面来看，这种粘土可能会经历大量的膨胀，从而导致裂缝膨胀关闭，从而使屏障自我修复，恢复其优异的水力性能。然而，这种膨胀只在某些情况下是可能的，这取决于试图使屏障重新饱和的流体的化学性质（即，如果渗透了水，它会自愈，但垃圾填埋场渗滤液的某些成分或化学复杂的基础土壤中的孔隙流体可能会抑制这种能力）。因此，需要进行基础研究，以了解这些材料中裂纹和自愈的复杂机制。然而，由于GCL内部的膨润土粘土被织物包裹，这些裂缝隐藏在视线之外，只能用x射线看到。这项拨款的目的是为一个x射线成像设备寻求资金，以便一个由5名理学硕士组成的团队。学生和4名博士生可以对协鑫衬管（和其他）材料进行无损检测（NDT），以量化协鑫在广泛的现场暴露条件下损坏的风险，并帮助与加拿大协鑫制造商合作开发新的更耐损坏的协鑫产品。