Jiangsu Province Engineering Research Center of Geoenvironmental Disaster Prevention and Remediation of School of Architecture and Civil Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212100, China.
College of Civil Engineering, Suzhou University of Science and Technology, Suzhou, 215009, China.
Environ Res. 2024 Aug 15;255:119110. doi: 10.1016/j.envres.2024.119110. Epub 2024 May 8.
Landfills require effective containment systems to prevent the leakage of leachate into the underground environment. Cutoff walls are commonly employed for this purpose, with options including rigid and flexible designs. In areas where structural strength is not a primary concern, flexible cutoff walls offer lower permeability and environmental benefits due to their lack of cement content, thereby reducing CO2 emissions. This study investigates the use of dredged sediment and attapulgite as materials for flexible cutoff walls. Through analyses of bound water content, free water content, hydraulic conductivity, and scanning electron microscopy, we explore the impact of confining pressures on cutoff wall permeability. Our findings reveal that the consolidation induced by confining pressure does not significantly alter the bound water content within the cutoff wall. Instead, changes in water content are predominantly attributed to variations in free water content. Under identical confining pressures, we observe a positive correlation between permeability and hydraulic gradient, with permeability increasing as the hydraulic gradient rises, and anti-permeability decreasing accordingly. Additionally, when holding the hydraulic gradient constant, increasing confining pressure leads to a continuous decrease in permeability. Microscopic analyses highlight that high confining pressure not only compresses pore diameter but also alters pore morphology, thereby influencing permeability. This study contributes to the understanding of cutoff wall behavior under different conditions. Our results demonstrate that increasing confining pressure during soil consolidation effectively reduces cutoff wall permeability to meet design standards. However, the influence of high leachate head on permeability should also be considered. These findings provide a more environmentally friendly and lower permeability option for landfill sites, which is significant for the design and enhancement of containment systems in landfill sites.
垃圾填埋场需要有效的防渗系统来防止渗滤液泄漏到地下环境中。截流墙常用于实现这一目标，其中包括刚性和柔性设计。在结构强度不是主要关注点的区域，柔性截流墙由于缺乏水泥含量而具有较低的渗透率和环境效益，从而减少了二氧化碳排放。本研究探讨了利用疏浚沉积物和凹凸棒石作为柔性截流墙的材料。通过分析结合水含量、自由水含量、水力传导率和扫描电子显微镜，我们探讨了围压对截流墙渗透性的影响。研究结果表明，围压引起的固结不会显著改变截流墙内的结合水含量。相反，水含量的变化主要归因于自由水含量的变化。在相同的围压下，我们观察到渗透率与水力梯度之间存在正相关关系，即随着水力梯度的升高，渗透率增加，反渗流相应减少。此外，当保持水力梯度恒定时，增加围压会导致渗透率持续降低。微观分析表明，高围压不仅压缩孔径，还改变孔径形态，从而影响渗透性。本研究有助于了解不同条件下截流墙的行为。研究结果表明，在土壤固结过程中增加围压可以有效地降低截流墙的渗透率，以满足设计标准。然而，还应考虑高渗滤液水头对渗透率的影响。这些发现为垃圾填埋场提供了一种更环保和低渗透性的选择，这对于填埋场防渗系统的设计和增强具有重要意义。
