Evaluation of Lateral Earth Pressure Coefficients for Municipal Solid Waste

在本项目中，将使用独特的大型废物测试设备进行实验室测试，以评估城市固体废物（MSW）的静态，主动和被动侧土压力。城市固体废物（MSW）中侧向土压力的大小，包括主动压力、被动压力和静止压力，以及影响这些侧向压力的因素在很大程度上是未知的，尽管它们对广泛的设计问题很重要。垃圾侧应力信息的缺乏不仅影响垃圾结构的设计，也影响垃圾抗剪强度的评价，从而影响垃圾填埋场的稳定性。为了解决这一知识差距，将使用一种新的侧向压力测量装置在0.75 m长、0.2 m宽、0.22 m高的重建样品上测量静止、主动和被动土压力。横向压力也将在0.45 m直径试件的简单剪切试验中测量。侧压力试验将提供城市生活垃圾侧土压力系数作为初始密度、最大粒径和围压的函数。该测试程序还将提供简单剪切测试中正应力的发展和演变的数据。对数据的解释将有助于了解城市固体垃圾的抗剪强度和侧向应力如何取决于应力状态和组成因素，包括纤维增强和城市固体垃圾的降解。该试验方案与先前试验方案之间的协同作用将提供有关城市生活垃圾力学行为的额外有价值的基础信息，包括对应力应变行为、各向异性、废物成分的影响和初始密度的影响的重要新见解。拟议测试计划的更广泛影响包括更经济和更具保护性的垃圾填埋场密封系统设计，加强对废物预处理和废物降解对抗剪强度和侧土压力的潜在影响的理解，提高垃圾填埋场容量的更经济有效的方法，改进垃圾填埋场补救策略，以及改进使用深地基的垃圾填埋场关闭后开发的工程方法。加强对废物抗剪强度的了解，将有助于更准确地评估堆填区的稳定性，提供更安全的设计，并可能增加某些地点的容量，延长设施的寿命，从而最大限度地减少对新地点的需求。加强对侧向应力的了解也有助于确定影响尾管完整性的条件。本研究项目中开发的信息也将有助于解决生物反应器和废物预处理等新兴技术对废物工程行为的影响。本研究开发的侧压力系数对于设计垃圾填埋场垂直扩展挡土墙系统、垃圾填埋场修复和垃圾填埋场封闭设计具有不可估量的价值。这项工作亦有助在关闭堆填区后发展旧堆填区，以促进旧堆填区的再利用，因为在关闭堆填区的堆填区顶部，支撑建筑物的桩必须承受沉降废物的下拉荷载，而估算下拉阻力则需要估算废物的侧压力系数和抗剪强度。

ABSTRACTIn this project, laboratory testing will be conducted using unique large scale waste testing equipment to evaluate at rest, active, and passive lateral earth pressures in municipal solid waste (MSW). The magnitude of lateral earth pressures in municipal solid waste (MSW), including active, passive, and at-rest pressures, and the factors that influence these lateral pressures are largely unknown, despite their importance to a broad range of design problems. The lack of information on MSW lateral stresses affects not only design of landfill structures but also the evaluation of MSW shear strength, and hence landfill stability. To address this knowledge gap, at rest, active, and passive earth pressures will be measured on 0.75 m-long, 0.2 m-wide, 0.22 m-tall reconstituted specimens using a new lateral pressure measurement device. Lateral pressures will also be measured in simple shear tests on 0.45 m diameter specimens. The lateral pressure tests will provide lateral earth pressure coefficients for MSW as a function initial density, maximum particle size, and confining pressure. The testing program will also yield data on the development and evolution of normal stresses in simple shear testing. Interpretation of the data will provide insight as to how MSW shear strength and lateral stresses depend on stress state and compositional factors, including fibrous reinforcement and degradation of the MSW. Synergies between this testing program and previous testing programs will provide additional valuable fundamental information on the mechanical behavior of MSW, including important new insights on stress strain behavior, anisotropy, the influence of waste composition, and the influence of initial density.Broader impacts of the proposed test program include more economical and more protective landfill containment system design, an enhanced understanding of the potential impacts of waste pre-processing and waste degradation on shear strength and lateral earth pressures, more cost effective methods for increasing landfill capacity, improved landfill remediation strategies, and improved engineering methods for post-closure development on landfills using deep foundations. An enhanced understanding of waste shear strength will enable more accurate evaluation of landfill stability, providing for safer designs and possibly allowing for increased capacity at some sites, extending the life of facilities and thus minimizing the need for new sites. Enhanced understanding of the lateral stresses can also help identify conditions that impact liner integrity. The information developed in this research program will also help address the implications of the emerging technologies of bioreactors and waste pre-processing on the engineering behavior of the waste. The lateral pressure coefficients developed in this study will be invaluable in designing retaining wall system for vertical expansion of landfills, for landfill remediation, and for landfill closure design. This work will also facilitate post-closure landfill development for beneficial reuse of old landfills, as piles supporting buildings on top of closed landfills must carry the downdrag loads from the settling waste and lateral pressure coefficients as well as waste shear strength estimates are required to estimate downdrag.