城市固体垃圾填埋场不均匀沉降分析

老垃圾填埋场竖向扩建时垃圾堆体的不均匀沉降控制是中间防渗衬垫系统设计的基础,正确计算和分析垃圾堆体的不均匀沉降将是老填埋场竖向扩建时成功与否的关键。研究了竖向扩建时垃圾不均匀沉降,并介绍了不均匀沉降的计算方 法,结合工程实例对老填埋场竖向扩建时垃圾不均匀沉降影响进行了分析,从工程技术角度提出了相应的解决方案。     

城市垃圾填埋场有机物降解沉降模型的研究

研究城市垃圾填埋场的有机物降解沉降是非常重要的,有机物的降解沉降是填埋场的主要沉降,并且降解沉降将持续很长一段时间,较大的沉降能够导致防渗系统的渗漏并损坏覆盖系统。由于垃圾的非均匀性,其土工特性随地域及时间而改变,所以,计算垃圾填埋场的降解沉降是比较困难的。在试验及理论推导的基础上,提出了一种有机物的降解沉降模型,该模型参数较少,利用该模型预测了天子岭垃圾填埋场的库容及有机物的降解沉降。     

河北省垃圾填埋场对地下水的污染分析

从河北省垃圾场的调查情况来看,全省处理生活垃圾的主要方式为垃圾填埋,且垃圾填埋场以未采取任何防渗措施的简易填埋场为主,约占垃圾场总数量的三分之二,已对环境造成一定污染。本文分析了河北省生活垃圾及其渗沥液化学成分,确定了生活垃圾及其渗沥液的主要污染成分。采用污染指数法,分析研究了河北省18个生活垃圾填埋场对地下水的污染情况,并总结出了垃圾填埋场对地下水的污染规律,对垃圾填埋场的建设和水资源的保护具有指导意义。     

湿润地区垃圾填埋场蒸发蒸腾覆盖层参数分析

蒸发蒸腾覆盖层相比传统覆盖层有许多优势,目前这种覆盖层主要应用于干旱和半干旱地区,但研究湿润地区垃圾填埋场蒸发蒸腾覆盖层的水分运移规律和工作性能很有必要。通过二维饱和-非饱和模型,分析覆盖层厚度、土壤类型、植被条件、气候条件等设计参数对蒸发蒸腾覆盖层防渗性能的影响,并对覆盖层中的水分运移规律及其工作性能和适用性进行研究。研究结果表明,随着覆盖层厚度和叶面积指数LAI增加,蒸发蒸腾覆盖层的最终透水量（穿过覆盖层水分）呈减小趋势,但覆盖层厚度和叶面积指数较大时透水量减小趋势不明显;拥有较大储水能力和适当渗透系数的覆盖层能够有效地减少透水量;降雨的季节性分布对蒸发蒸腾覆盖层性能有很大影响,当多雨期与高温期分布一致时,蒸发蒸腾覆盖层的性能可满足设计要求;在非饱和条件下,毛细阻滞型覆盖层利用粗-细粒土之间水力特性的差异形成毛细阻滞效应减少水分向下入渗,其防渗性能优于单一土层型覆盖层,但在不利气象条件组合下,该毛细阻滞作用可能失效, 其防渗性能将大大下降。     

垃圾填埋场覆层甲烷生物减排技术综述

垃圾填埋场服役期间会因微生物降解有机物释放大量甲烷,即使有气体收集装置,仍有甲烷逃逸到大气中。甲烷气体是造成温室效应的重要气体之一。甲烷氧化菌是以甲烷为唯一碳源的微生物,具有其优良的甲烷氧化效能。在中小型填埋场、老旧填埋场及开启集气装置已不再经济的大型填埋场,可在填埋场覆层中掺入甲烷氧化菌,对甲烷进行生物氧化,减少垃圾填埋场的甲烷释放量,从而减少温室效应,达到环保的目的。文章回顾了近些年国内外对甲烷氧化菌及其甲烷氧化效能的相关研究,对甲烷氧化菌的分类及其甲烷氧化机理,影响甲烷氧化菌氧化效能的因素以及甲烷氧化菌在垃圾填埋场中的应用等研究成果进行了总结,并对其今后的研究和应用提出了展望。     

非卫生垃圾填埋场渗滤液污染防治对策研究

针对非卫生垃圾填埋场环境污染问题,以某垃圾填埋场为例,通过 WHI UnSat Suite软件 HELP模块计算不同填埋条件下渗滤液渗漏量。利用GMS模拟了该垃圾场中心抽水条件下污染物迁移变化规律。结果表明,简单地表防渗条件下,渗滤液渗漏量为现状条件下的50%,增铺 HDPE土工膜后,渗漏量可减少99%。卫生填埋渗滤液仅为现状条件下的3.6＆#215;10-3倍。当抽水量为2000 m3/d时,Cl-浓度呈明显下降趋势,由84 mg/L降至80.1 mg/L。     

黄土作为西北地区填埋场覆盖层的可行性及设计厚度分析

中国西北地区气候以干旱和半干旱为主,黄土广泛分布。首先介绍了西北地区3个代表性城市近50 a的气候条件和3类黄土的粒径分布及储水能力,在此基础上利用Chen、Benson等提出的水量平衡分析方法对黄土土质覆盖层在我国西北地区应用的可行性进行了探讨,并计算分析了单一型黄土覆盖层的设计厚度。分析结果表明: 西北地区夏季高温多雨植被生长茂盛而冬季降雨较少,降水和腾发作用有较好的同步对应关系,适合土质覆盖层的应用。采用黄土作单一型土质覆盖层的设计厚度在0.54～1.92 m之间,从干旱、半干旱到半湿润气候区,设计厚度逐渐变厚,其具体设计厚度与气候条件和黄土种类密切相关;在同一气候区采用粉性黄土所需厚度最薄,而采用砂性黄土则最厚。西北地区采用黄土作填埋场终场土质覆盖层具有技术可行性和良好的经济效益,值得进一步开展工程实践和更深入的研究。     

垃圾填埋场的沉降分析、计算及灰色模型预测

城市垃圾填埋场的沉降问题一直是长期困扰从事垃圾填埋研究工作者的一个非常重大的问题，它的解决对于提高垃圾场的潜在处理能力、增加填埋场的有效存贮容量有着十分重大的意义。本文首先分析了垃圾场的沉降原理，并给出了计算方法；而后应用灰色系统理论，对沉降实际数据进行处理，建立灰色动态GM模型，作出对填埋过程中和封顶后的沉降预测，取得了较好的效果。     

软土地基上垃圾填埋场的固结和沉降分析

卫生填埋是城市废弃物处理的主要方式。垃圾填埋场多选址于山间沟谷或地基强度较高的地区。然而在平原、尤其滨海地区,垃圾填埋场往往只能建在强度较低的软土上。此时地基土的固结沉降和稳定问题将直接影响垃圾填埋场安全运行。但在这方面的实践经验和科研工作都做得不够。一方面要保证垃圾降解的有毒有害液体不能渗入地基内,污染地下水;另一方面,软弱地基又需要尽快固结,以提高地基承载力和地基土的强度。这给地基设计和地基处理提出了新的课题。本文结合某垃圾填埋场进行研究,分析填埋场地基的固结和沉降特性,为软基上垃圾填埋场建设提供参考。     

封顶覆盖黄土气体渗透特性测试及填埋气一维运移分析

黄土在我国西北地区广泛分布,是当地垃圾填埋场封顶覆盖层的主要材料,该材料的气体渗透特性直接影响了覆盖层对填埋气释放的控制效果。利用渗析技术和自制的气体渗透系数测量装置,模拟和测试了干湿气象条件下覆盖黄土服役含水率变化及其对气体渗透系数的影响,并建立填埋气在垃圾体和覆盖层中的一维稳态运移模型,分析了覆盖层气体渗透系数和抽气速率对填埋气释放控制效果的影响。研究结果表明：渗析技术能有效模拟覆盖黄土服役含水率的变化,压实黄土试样的气体渗透系数介于10-17～10-12 m2量级,随服役含水率的增加而降低,且对于压实度比较高的黄土降低得更加明显;覆盖层底部的填埋气压随气体渗透系数的减小而增大,通过覆盖层下部的气体扩散层负压抽气等措施,可有效减小覆盖层底部气压和填埋气的释放量。     

填埋场封场覆盖系统稳定性统一分析模型构建及应用研究

为探讨不同界面形式下有限长与无限长填埋场边坡封顶覆盖系统稳定特性,通过模型试验确定了不同边坡长度下界面分别为土工膜和三维网时封场覆盖系统的破坏模式与失稳坡度。基于试验结果建立了覆盖系统的许可破坏模式及其速度场,利用极限分析上限法建立了考虑界面强弱特性以及坡长有限与无限形式的覆盖系统稳定性统一分析模型,并利用模型试验结果对该理论进行验证。运用文中提出的理论模型对新型环保的垃圾填埋场封场覆盖生态污泥腾发覆盖技术（EST）中防护基材稳定性进行定量分析。研究结果表明：覆盖层失稳时,滑移面分为上、下两段,上段为平行于坡面的直线,下段为位于覆盖层内部近似为与坡面成一定夹角的直线;减小边坡长度能使覆盖系统稳定特性提高,但减小覆盖层厚度对覆盖系统稳定的增减影响与界面强弱形式有关;覆盖系统稳定特性主要由界面抗剪强度控制,增加基材强度并不能大幅度提升覆盖系统稳定特性,且增加界面黏聚力对覆盖系统稳定贡献明显优于增加界面摩擦系数。     

城市固体废物(MSW)填埋场中单元覆盖层防渗研究进展

根据世界各国的经验，在未来相当长的时期内，填埋仍将是城市固体废物（MSW）的主要处置方式，但MSW渗滤液的产生及处理不仅加大了填埋场的建设及运行成本，而且也增大了发生二次污染的风险。MSW填埋结构中的单元覆盖层具有防止降水入渗、减少（或消除）渗滤液数量的重要作用，而这种作用能否充分发挥则取决于其渗透性能，因此，单元覆盖层的防渗研究具有重要的实用价值。文章重点介绍了该领域研究已取得的进展，包括阳离子、阴离子、pH及氧化物等对饱和土体渗透性的影响、非饱和土体胀缩行为与渗透性变化的描述及饱和、非饱和土体隔水性能优化等；提出了该领域研究中存在的问题及未来发展方向。     

Numerical simulation on the cracking and failure law of compacted clay lining in landfill closure cover system

According to the mass conservation equation of solid phase, water transport, air migration and enthalpy balance equations in a deformable and unsaturated porous medium, and the mechanics model, a thermal‐hydro‐mechanical (THM) coupling mathematical model is developed in order to accurately predict the crack propagation of the compacted clay lining (CCL) in a landfill closure cover system. Numerical simulation analysis of the cracking and failure of the CCL in a landfill closure cover system under complex conditions (landfill gas pressure, variation of soil surface temperature, moisture loss of coverage soil, and uneven settlement of landfilled MSW (municipal solid waste)) is performed. The results show that the cracks are discovered firstly on the soil surface and then extend to the deeper cover system and became bigger. The cracks had broken through the closure cover system at 30 days. Over the depth range of 0.06 m, the change rate of settlement is found to be the highest because of the strong influence of temperature. The rise of temperature around the cracks is fast when the CCL is broken through by the cracks. There is a hollow area near the cracks over the depth range from 0.15 to 0.7 m, and the temperature stabilize at around 11°C without any obvious reduction. Under the condition of evaporation, the main crack in the CCL is similar to a pumping well, which causes more rapid moisture content reduction around the cracks. Vertical deformation increases linearly with depth in the process of deformation and cracking of CCL induced by uneven settlement of landfilled MSW. Copyright © 2014 John Wiley & Sons, Ltd.     

基于信息熵与多重分形理论的非均匀流动分析

根据粘土和壤土中非均匀水流运动的示踪试验, 研究了土壤水非均匀流动模式, 并基于信息熵与多重分形理论探讨了多孔介质中流动的非均匀性质.不同土质试验研究的分析结果表明, 各深度信息熵与特征长度具有相反的变化趋势.非均匀流动多重分形特性分析表明, 非均匀流动分布具有很强的自相似性, 但并不是在所有研究尺度范围内都满足标度不变性, 在显色比例相近的情况下, 壤土和粘土中水流运动标度不变性的范围表现出显著的差异.      

Related information measures for the associations of earth-science variables

A basic task in earth-science data integration is to quantify variable associations. Although manv measures have been used to determine the associations between quantitative variables, the ability to quantify qualitative attributes (e.g., categorical) is limited. Moreover, most traditional association measures are restricted to linear correlations or similarities, for example, correlation coefficient. The measures proposed in this report are designed on the basis of Shannon's entropy concepts, including directional related information, ordinary related information, and partial related information. The directional related information quantifies the association of one variable in terms of another. The ordinary related information determines the mutual association of two variables. The partial related information characterizes the association of an individual stale of one variable in terms of another variable. The properties of these measures are discussed and their sample estimates are derived from both maximum likelihood and Bayesian methods. The relations between these measures are illustrated by using synthetic examples. Two applications of these measures also are developed, including the selection of variables and evaluation of mineral resources. Finally, a case study is given to demonstrate the use of the measures in mineral resources evaluation.     

北京北天堂地区城市垃圾填埋对地下水的污染

本文介绍了由于城市垃圾填埋而引起的地下水资源污染问题.以北京南部北天堂垃圾填埋场的污染状况为例进行调查,对其进行污染综合评价,通过建立数学模型模拟污染物在几种条件下的地下运移情况及补救效果,对污染控制进行了模拟、分析及提出相关的控制与治理的建议及措施.     

Stochastic finite element modelling of water flow in variably saturated heterogeneous soils

Water flow is greatly influenced by the characteristics of the domain through which the process occurs. It is generally accepted that earth materials have extreme variations from point to point in space. Consequently, this heterogeneity results in high variation in hydraulic properties of soil. In order to develop an accurate predictive model for transport processes in soil, the effects of this variability should be considered. In this study a two‐dimensional stochastic finite element flow model was developed for simulation of water flow through unsaturated soils. In this model, the stochastic partial differential governing equation of water flow, obtained from implementation of the perturbation‐spectral stochastic method on classical Richard's equation, was solved using a finite element method in the space domain and a finite difference scheme in the time domain. The effective hydrological parameters embedded in the mathematical model depend on time derivatives of capillary tension head; this makes possible to consider the hysteresis due to large‐scale variability of soil hydrological properties. The model is also capable of simulating infiltration and evaporation events and rapid change in the land surface boundary condition from one type event to another, based on a scheme used in the model for implementation of land surface boundary condition. The model was validated with the data obtained from a layered lysimeter test. The model was also used to simulate water flow under a long irrigation furrow. The results obtained with this model show better agreement with experimental measurements in comparison with a deterministic model. The possible reason for this agreement is that in the developed model, the influence of the variability of the properties of soil and effects of parameter hysteresis on water flow and water content redistribution are considered. Copyright © 2010 John Wiley & Sons, Ltd.     

Suitability of Hydrologic Evaluation of Landfill Performance (HELP) model of the US Environmental Protection Agency for the simulation of the water balance of landfill cover systems

 Cover systems are widely used to safeguard landfills and contaminated sites. The evaluation of the water balance is crucial for the design of landfill covers. The Hydrologic Evaluation of Landfill Performance (HELP) model of the US Environmental Protection Agency was developed for this purpose. This paper discusses some limitations of version 2 of this model and some operational difficulties for the use of this model in Germany, which has been developed for the United States. The model results are tested against field data of the water balance, measured on test fields on the Georgswerder landfill in Hamburg. Theoretically, HELP considers gravitational forces as driving forces of water flow only. Therefore capillary barriers cannot be simulated. Furthermore, the formation of and the flow through macropores are not considered, a main critical process that the diminishes the effectiveness of compacted soil liners. In the output comparison, the matching of measured and simulated data is quite good for lateral drainage, but failed for surface runoff and liner leakage through compacted soil liners. A further validation study is planned for HELP version 3 using a broader range of test field data. Received: 10 January 1995 · Accepted: 14 November 1995