Hettiarachchi Hiroshan, Meegoda Jay, Hettiaratchi Patrick
Department of Civil Engineering, Lawrence Technological University, 21000 West Ten Mile Road, Southfield, MI 48075, USA.
Waste Manag. 2009 Mar;29(3):1018-25. doi: 10.1016/j.wasman.2008.08.018. Epub 2008 Oct 23.
This manuscript describes a model that can predict settlement at variable moisture and pressure conditions as encountered in bioreactor landfills. In this model mechanical compression of municipal solid waste (MSW) was accounted with the help of laboratory compression tests. To model biodegradation-induced settlement, biodegradation of MSW was assumed to obey a first order decay equation. Richards equation was used to model moisture transport in the waste mass and mass balance was used to link settlement with gas pressure. The functionality of the numerical formulation was examined using a hypothetical bioreactor landfill. Four scenarios were analyzed to demonstrate how the proposed model can be used to analyze the settlement behavior of bioreactor landfills as well as dry landfills. The model predicted higher strains when moisture and gas pressures were incorporated into the settlement process. Results also indicated that the prediction capability of a MSW settlement model can be improved by coupling the settlement mechanisms with the generation and dissipation of gas pressure and the moisture distribution. The model is also able to predict landfill density values, and the predicted MSW wet density after 25 years agreed reasonably with those reported in literature.
本手稿描述了一种模型，该模型可以预测生物反应器填埋场中在可变湿度和压力条件下的沉降情况。在该模型中，借助实验室压缩试验来考虑城市固体废物（MSW）的机械压缩。为了模拟生物降解引起的沉降，假设MSW的生物降解服从一级衰减方程。采用理查兹方程对废物堆体中的水分运移进行建模，并利用质量平衡将沉降与气压联系起来。使用一个假设的生物反应器填埋场来检验数值公式的功能。分析了四种情景，以说明所提出的模型如何用于分析生物反应器填埋场以及干式填埋场的沉降行为。当将湿度和气压纳入沉降过程时，该模型预测出更高的应变。结果还表明，通过将沉降机制与气压的产生和消散以及水分分布相结合，可以提高MSW沉降模型的预测能力。该模型还能够预测填埋场密度值，并且预测的25年后MSW湿密度与文献报道的值合理吻合。
