【作者】 陈若曦；

【导师】 陈云敏； 朱斌；

【作者基本信息】 浙江大学 ， 岩土工程， 2008， 硕士

【摘要】 随着我国经济的快速发展和城市化水平的提高,城市生活垃圾产量日益增加,而目前为止填埋仍是垃圾处理的主要方式。由于垃圾体成分复杂,压缩性高且分布不均匀,填埋场容易发生局部沉陷甚至塌方等情况。下卧垃圾堆体发生局部沉陷时沉陷区上方的衬垫系统产生较大的内力和变形,可能破坏衬垫系统,造成渗滤液的渗漏,并带来填埋场污染事故甚至失稳破坏。鉴于目前对衬垫系统抗沉陷的设计都局限在工程经验或半经验的基础上,因而有必要开展衬垫系统抗沉陷的机理研究,并在此基础上提出合理的工程设计方法。本文首先根据模型试验和数值分析结果,基于主应力轴旋转理论修正了Terzaghi松动土压力公式中的侧向土压力系数,修正后的Terzaghi松动土压力公式计算结果与实测和数值分析结果吻合良好;同时考虑土拱效应,提出了基于位移相关的竖向土压力表达式。从而为局部沉陷条件下衬垫系统的合理受力与变形分析奠定了基础。结合所提出的位移相关竖向土压力的表达式,建立了填埋场平面应变和轴对称两种形式局部沉陷条件下衬垫系统受力变形的解析分析模型,模型考虑了衬垫系统大变形和沉陷区周围衬垫系统滑移对衬垫系统受力和变形的影响。编制了相应的Matlab计算程序,计算结果得到了FLAC数值分析结果的验证,并进行了参数分析。最后,根据工程的实际情况,结合Giroud(1990)抗局部沉陷的工程设计方法,提出了基于位移相关竖向土压力的填埋场衬垫系统抗局部沉陷的工程设计方法,并应用于实际工程。对于衬垫系统上方垃圾堆体小于30m的情况,Giroud(1990)传统设计方法计算结果偏保守,而当衬垫系统上方垃圾堆体大于30m时,该方法则偏不安全。由于本文提出的工程设计方法合理考虑了衬垫上方竖向土压力随竖向位移的变化,其分析结果更接近实际情况。更多还原

【Abstract】 With the rapid economic development and urbanization, the generated quantity of Municipal Solid Waste (MSW) increased at a high speed in China. The construction of landfill is still the main measures to deal with MSW. Local subsidence often occurs in landfill due to the complexity, high compressibility of components of MSW and its non-uniformity distribution. Large internal force and deformation would be induced along geosynthetic liner system in subsidence areas subjected to the local subsidence, which would destroy the liner system and lead to leakage of leachate. Moreover, the high leachate level resulted by the leakage of the liner system may cause the instability of the MSW fill. Until recently, research on the liner system subjected to the local subsidence only based on the engineering experience, it is necessary to study its mechanism and proposed a reasonable design method for this problem.Firstly, based on model tests and numerical analyses, the lateral coefficient of earth pressure expression in Terzaghi loosen earth pressure formulate is modified, and its calculated results are in good agreement with the model tests and numerical simulations. Also, displacement-related vertical earth pressure expression is proposed considering arch effect.Secondly, based on tensile cable and large strain circle membrane theory, the analytical models of the liner systems considering the plane strain and axial symmetry local subsidence are presented respectively. The models can take into account the effects of large deformation of liner system, sliding of the liner system near by the subsidence area and the displacement-related vertical earth pressure. Good agreement between the computed results by the proposed MATLAB programs and the FLAC numerical analyses results validates the present analytical models. Parametric studies are also given.Finally, associate with Giroud (1990) resisting local subsistence design method, a new engineering design method of the liner system resisting local subsistence in landfill is proposed based on displacement-related vertical earth pressure theory, it is applied to a design case in practice. If the thickness of the MSW overlying on the liner system is smaller than 30 m, the Giroud (1990) design method is conservatively, otherwise, its predicted allowable tensile force of the liner system will be smaller than the true one due to it cannot taken into accout the displacement-related vertical earth pressure.更多还原