Modeling Coupled Dynamic Processes in Landfills: Holistic Long-Tern Performance Management to Improve Sustainability

许多接受城市固体废物的工程填埋场被归类为“干墓填埋场”，因为由于低湿度条件，废物降解非常缓慢。作为一种替代方案，生物反应器垃圾填埋场已经出现，以应对这些条件。在生物反应器填埋场，渗滤液循环系统增加水分和加速降解。生物反应器填埋场的性能是水-生物-机械耦合过程的结果；然而，业界缺乏一个全面的，整体的数学模型，考虑和有效地分析这些耦合过程在垃圾填埋场。本项目将开发一套新的耦合数学工具，以设计和运作稳定、有效和可持续的工程堆填区，从而最大限度地减少对周围环境和公众的长期风险。该工具将使从业者和监管机构能够预测高度复杂的垃圾填埋场稳定期，并允许通过准确计算不同的沉降和稳定期来规划垃圾填埋场空间的有益再利用，例如娱乐设施。有了可控制的、可预测的、迅速的城市固体废物分解和较短的稳定期：(a)可以开采和处理不可降解的城市固体废物，减少了填埋区内填埋物的数量；(b)可以缩短关闭后的监测，并大大减少有关开支；(c)对土工合成衬垫的长期性能和相关环境风险的担忧可以得到解决。这项研究涉及多个学科，包括地球环境工程、可持续工程、生物学和计算力学。多学科研究将为代表性不足的群体参与研究提供独特的机会。所提出的建模工具将结合并同时求解两相流模型、大应变显式力学模型和一阶衰变生物降解模型。该模型将考虑垃圾属性的并发变化，以预测垃圾填埋场的耦合过程。具体而言，项目范围将包括：(a)开发一个新的数学模型，该模型可以解释非均质废物、两相流和耦合的水-生物力学过程，并有效地预测垃圾填埋场的时空行为；(b)通过实验室和实地研究验证模型，以获得模型结果准确性的置信度；(c)预测空间和时间填埋场沉降、边坡稳定性和线性系统由于耦合过程而产生的剪切响应。(d)基于概率分析，评估控制堆填区性能的主要系统变量，以及(e)应用该工具对过去的堆填区故障进行法医调查。该项目将为设计稳定和有效的工程堆填区以及利用水力-生物-机械耦合过程优化现有堆填区提供工具。

Many engineered landfills that accept municipal solid waste are classified as "dry tomb landfills" because waste degrades very slowly due to low moisture conditions. As an alternative, bioreactor landfills have emerged to counter those conditions. In bioreactor landfills, leachate recirculation systems increase moisture and accelerate degradation. The performance of bioreactor landfills results from coupled hydro-bio-mechanical processes; however, industry lacks a comprehensive, holistic mathematical model that considers and effectively analyzes these coupled processes in landfills. This project will develop a new coupled mathematical tool to enable the design and operation of stable, effective and sustainable engineered landfills, thereby minimizing long-term risks to the surrounding environment and public. The tool will enable practitioners and regulators to predict the highly complex landfill stabilization period, and allow for the planning of beneficial reuse of landfill space, such as recreational facilities, by accurately accounting for a differential settlement and stabilization period. With controlled, predictable, rapid municipal solid waste decomposition and a reduced stabilization period: (a) non-degradable municipal solid waste may be mined and processed, reducing the amount of landfill mass encapsulated within a landfill; (b) post-closure monitoring can be shortened and associated expenditures considerably reduced; and (c) concerns about the long-term performance of geosynthetic liners and related environmental risks can be addressed. This research involves multiple disciplines, including geoenvironmental engineering, sustainable engineering, biology, and computational mechanics. The multi-disciplinary research will provide a unique opportunity to underrepresented groups to participate in research.The proposed modeling tool will combine and simultaneously solve a two-phase flow model, a large-strain explicit mechanical model, and a first-order decay biodegradation model. The model will account for concurrent changes in waste properties to predict coupled processes in landfills. Specifically, the project scope will include: (a) development of a new mathematical model that can account for heterogeneous waste, two-phase flow, and coupled hydro-bio-mechanical processes, and effectively predict spatial and temporal behavior of landfills, (b) model validation with laboratory and field studies to attain a confidence level in the accuracy of the modeling results, (c) prediction of spatial and temporal landfill settlement, slope stability and shear response of liner systems due to coupled processes, (d) assessment of the major system variables that control the performance of landfills based on probabilistic analysis, and (e) application of the tool for forensic investigation of past landfill failures. The project will provide a tool for designing stable and effective engineered landfills and optimizing existing landfills using coupled hydro-bio-mechanical processes.