垃圾填埋场喷塑覆盖技术

1 国内外概况 随着经济的发展,城市人口的增加,生活垃圾的数量不断增多。上海市每年就有300多万t垃圾需要处置。当前世界各国都面临着“垃圾包围城市”的严峻局面。 处理城市垃圾的主要方法有卫生填埋、焚烧和堆肥3种,各国的国情不同,上述处理方法所占的比重也不同,但总的来说,发达国家采用卫生填埋占60％～70％、焚烧占25％～30％、堆肥占5％～10％,发展中国家采用     

浙江宁波：鄞州垃圾填埋场通过无害化等级现场考核

近日,中国环境卫生协会组织相关专家对宁波市鄞州区生活垃圾卫生填埋场无害化等级进行现场考核。专家组首先听取了填埋场建设、运行工作情况的介绍,经过实地勘察，查验资料,分析论证，专家组对该场各项考核指标都相当满意。[第一段]     

安定垃圾卫生填埋场

安定垃圾卫生填埋场位于大兴区安定镇，占地面积21．6公顷，填埋场分填埋区和生活区两部分。日处理量为1100吨之多，每年可填埋垃圾约40万吨左右。     

垃圾填埋场终场腾发覆盖系统的研究进展

垃圾填埋场的传统覆盖形式为压实黏土、土工合成材料、土工膜或由这些材料组合而成的屏障型覆盖系统,由于垃圾降解和固结沉陷等原因,几乎所有屏障型覆盖系统在长期使用过程中都可能破坏失效。近年来,腾发覆盖作为一种替代覆盖技术在美国的垃圾填埋场得到广泛应用。腾发覆盖由一层植被土构成,它利用非压实土层储蓄渗入的降水、依靠植物的蒸腾和土壤蒸发消耗土壤水,从而实现渗沥污染控制。腾发覆盖的植被宜采用灌木和草皮混合形式,覆盖土层宜采用壤土或黏壤土,土体密度宜为1.1～1.5g/cm3,土层厚度取决于植被和当地气候。腾发覆盖是一种经济、实用、易于建造和维护的生态覆盖技术,但不宜用于蒸发量∶降水量〈1.2的沿海地区。     

乐山市垃圾卫生填埋场及收集系统工程设计

乐山市在生活垃圾收集和处理方面 ,当地政府十分重视。 1997年 2月 ,该项目被列入四川省第一期世行贷款城建环保项目之列。设计规模为2 0 15年 4 0 0ｔ/ｄ。卫生填埋场占地 2 84亩 ,总库容2 30万立方米 ,服务周期约 2 0年。1　设计规模及垃圾成份1 1　设计规模　根据乐山市中心城区总体规划及 1998年实测的垃圾收集量 ,推算该市人均垃圾产量为 0 8ｋｇ/人·ｄ。采用人均垃圾产量法 ,对1998～ 2 0 15年逐年垃圾产量进行了预测。根据预测结果 ,确定设计规模为 :2 0 0 0年 180ｔ/ｄ ;2 0 0 5年 2 5 0ｔ/ｄ ;2 0 10年 35 0ｔ/ｄ ;2 0 15年 4 0 …     

垃圾填埋场覆盖系统受损案例分析

结合国外垃圾填埋场覆盖系统受损的若干案例,分析了屏障型覆盖系统发生渗漏、滑坡、沉陷、侵蚀的各种机制,分析了在覆盖系统的设计和施工中如何避免这些问题,以保证垃圾填埋场的正常运行.     

垃圾填埋场调节池浮盖系统设计

介绍了垃圾填埋场调节池浮盖系统的组成,针对高邮市生活垃圾卫生填埋场新建调节池及原有调节池顶部无覆盖的现实,进行了浮盖系统的设计,并介绍了其施工方法.工程的顺利实施有效阻止了臭气的散逸和雨水的流入.     

垃圾体渗透性试验及填埋场水文分析研究

探讨了城市生活垃圾水力学参数的实验测试方法,设计并制作了一套实验装置,对在不同压力条件下填埋体的渗透系数进行了实验测试。通过对实验结果的拟合分析,阐述了垃圾体渗透系数随孔隙比变化的规律。采用美国环保署的HELP模型,利用垃圾体在不同压力条件下的渗透试验结果,对填埋场进行了水体平衡分析。结果表明压力场对填埋场水文状况的影响不容忽略。     

垃圾填埋场的防渗、排水及污水处理

垃圾填埋场的高浓度渗出液会对水资源造成严重污染。本文以潭口垃圾 填埋场工程为例,介绍了消除污染的防渗、排水、污水处理工程三项技术。     

辽阳市垃圾填埋场地下水污染调查与评价

在我们的日常生活中,会制造出非常多的垃圾,很多人对垃圾的处理方法就是直接的填埋,经过研究发现,这种填埋式的垃圾处理方法会对地下水造成污染。为了让更多的人了解来及填埋的危害,文章对辽阳市垃圾填埋场地下水污染展开了调查工作,并对此进行相关的评价,让更多的人了解到垃圾直接填埋所产生的危害。     

黄土–碎石毛细阻滞覆盖层储水能力实测与分析

中国西北地区气候较干旱,黄土分布广泛。就地取材采用当地的黄土作垃圾填埋场封场土质覆盖层具有技术可行性和良好的经济性。在西安江村沟垃圾填埋场建造了国内首个20m×30m大尺寸黄土–碎石毛细阻滞覆盖层现场试验基地,在基地开展了极端降雨试验。水量分配测试结果表明:总降雨量214.8 mm;坡面径流1.7 mm,占总降雨量的0.8%;土层存储(含蒸发)199.57 mm,占总降雨量的92.9%;渗漏13.53 mm,占降雨量的6.3%。基质吸力与水份运移规律分析结果表明:持续降雨条件下毛细阻滞覆盖层(900 mm)细粒土中表层土(15 cm深度以上)和底层土(85cm深度以下)的孔压(或体积含水率)均较高;底层土孔压(或体积含水率)较高是由于碎石–黄土界面间毛细阻滞效应对水份下渗的阻滞作用,这是有别于单一土层降雨入渗水份运移的显著特征。储水能力评估结果表明:极端降雨试验实测黄土–碎石毛细阻滞覆盖层有效储水量为251.95 mm。采用室内吸湿土水特征曲线评估覆盖层有效储水能力,有效储水量理论值S_(fac)为218.75 mm,实测值较理论值大15.18%,结果偏于安全。采用现场吸湿土水特征曲线评估覆盖层有效储水能力,有效储水量理论值Sfac为278.32 mm,实测值比理论值小9.47%,偏于危险。防渗设计中建议采用室内吸湿土水特征曲线。     

垃圾填埋场封顶系统最大饱和深度的计算

封顶系统饱和深度的最大值直接关系到封顶系统坡体稳定性和排水层的设计。根据水量平衡原理,以扩展的Dupuit假定为基础,建立填埋场封顶系统最大饱和深度的计算模型,应用该模型研究封顶系统饱和深度随时间的变化过程,分析不同因素对封顶系统最大饱和深度的影响规律。研究结果表明:在强降雨和高排水率情况下,饱和深度在较短的时间内达到了稳定,采用渗透系数较大的排水材料铺设排水层、减小水平排水距离、增大斜坡坡度等措施都能在一定程度上减小封顶系统最大饱和深度,在最大饱和深度较大的情况下,水平排水距离是比排水坡度更为显著的影响因素。     

不同降雨模式条件下填埋场封顶系统最大饱和深度

根据水量平衡原理,以扩展的 Dupuit 假定为基础,建立了填埋场封顶系统饱和深度的计算模型,应用该模型研究了均布型、前峰型、中峰型和后峰型 4 种降雨模式对填埋场封顶系统饱和深度的影响,并分析了不同降雨模式条件下降雨强度、排水层渗透系数、水平排水距离和斜坡坡度对封顶系统最大饱和深度的影响规律。计算结果表明,前峰型降雨模式条件下封顶系统饱和深度的增长速率最快,后峰型增长速率最慢,均布型和中峰型对应的饱和深度增长速率介于上述两者之间;封顶系统最大饱和深度随排水层渗透系数的变化有一敏感范围,处于该范围内最大饱和深度随排水层渗透系数的增加显著减小;水平排水距离的增加会引起封顶系统最大饱和深度明显的增大。     

挥发性气体通过填埋场复合覆盖层的一维扩散解析解

为了评价填埋场覆盖层对挥发性气体的防渗性能,建立了挥发性气体在复合覆盖层中的扩散运移模型并采用分离变量法获得了模型解析解。解析解的计算结果与数值解结果吻合得较好。分析结果表明,对于土工膜/土工复合膨润土垫（GM/GCL）与土工膜/压实黏土（GM/CCL）组成的覆盖层,覆盖层顶部气体扩散达到稳态的时间比较接近,约为1.6 a;对于压实黏土（CCL）系统达到稳定状态的时间为0.5 a;稳态时通量依次为6.0×10⁵,1.0×10⁶和7.4×10⁵ mg/ha/a。在这3个覆盖层系统中,GM/CCL对气体扩散的控制性能最差。对于GM/GCL,GCL含水饱和度从0.85增加到1时,覆盖层顶部通量减小了82.5%。饱和时GM/GCL系统顶部气体达到稳态的时间是非饱和情况下的约100倍。对于GM/CCL,CCL含水饱和度从0.1增加到0.85时,覆盖层顶部通量减小了近1个数量级。含水饱和度的变化可导致覆盖层顶部挥发性气体稳态时通量发生数量级的变化。     

填埋场斜坡上土工膜受力特性的离心模型试验研究

由于垃圾土沉降大,斜坡上土工膜易受到较大下拽力而破损,影响衬垫系统防渗功能。通过离心模型试验对填埋场斜坡上土工膜在垃圾土重力和沉降作用下的拉力和应变进行了研究,并通过FLAC数值对比分析,可获得如下结论：试验采用的模型垃圾土能很好地模拟现场垃圾土,模型土最大沉降量可达土层厚度的20%;土工膜存在中性点,以中性点为界土工膜可分为受拉区和受压区,中性点的位置与坡度和沉降有关,从坡顶到中性点拉应变逐渐变小,从中性点到坡脚压应变先增大后减小;坡度和沉降是影响土工膜拉力发展的重要因素,坡度或沉降越大,拉力越大,沉降是通过改变界面强度的发挥程度来影响土工膜拉力的发展;当采用单糙面土工膜（上光下糙）时,外部作用力很难向土工膜下界面传递,土工膜锚固端拉力几乎为零。     

Shear strength of geosynthetic composite systems for design of landfill liner and cover slopes

Torsional ring shear tests were performed on composite specimens that simulate the field alignment of municipal solid waste (MSW) landfill liner and cover system components. Simultaneous shearing was provided to each test specimen without forcing failure to occur through a pre-determined plane. Composite liner specimens consisted of a textured geomembrane (GM) underlain by a needle-punched geosynthetic clay liner (GCL) which in turn underlain by a compacted silty clay. Hydrated specimens were sheared at eleven different normal stress levels. Test results revealed that shear strength of the composite liner system can be controlled by different failure modes depending on the magnitude of normal stress and the comparative values of the GCL interface and internal shear strength. Failure following these modes may result in a bilinear or trilinear peak strength envelope and a corresponding stepped residual strength envelope. Composite cover specimens that comprised textured GM placed on unreinforced smooth GM-backed GCL resting on compacted sand were sheared at five different GCL hydration conditions and a normal stress that is usually imposed on MSW landfill cover geosynthetic components. Test results showed that increasing the GCL hydration moves the shearing plane from the GCL smooth GM backing/sand interface to that of the textured GM/hydrated bentonite. Effects of these interactive shear strength behaviors of composite liner and cover system components on the possibility of developing progressive failure in landfill slopes were discussed. Recommendations for designing landfill geosynthetic-lined slopes were subsequently given. Three-dimensional stability analysis of well-documented case history of failed composite system slope was presented to support the introduced results and recommendations.     

Field trial of a reinforced landfill cover system: performance and failure

The geotechnical stability of an inclined multilayer capping depends on the shear strength available along the various interfaces. If the slope is very steep an additional reinforcing geosynthetic may be used to obtain a safer condition. Full-scale field trials can provide better resolution data on the reinforcement behaviour than conventional calculation methods based only on laboratory tests. The paper deals with a field trial carried out on multilayer capping, reinforced with a geogrid, in an Italian landfill. The geogrid behaviour was monitored for a month using displacement sensors and pressure cells located along the slope and in the anchor trench. Subsequently, the cover system was led to collapse by cutting the reinforcement and an analysis of the reinforcement behaviour and its relevance in the system stability were studied. This paper discusses in detail the setup of the field trial and the experimental data recorded during installation, monitoring, and failure phases of the system. The deformation behaviour of the geogrid during the entire test was recorded and analysed. The resulting data highlight the effects of the construction process on the geogrid behaviour including the contribution of geogrid creep characteristics until the failure.     

Hydro-mechanical behavior of geogrid reinforced soil barriers of landfill cover systems

This paper examines the hydro-mechanical behavior of soil barriers with and without the inclusion of geogrid reinforcement within the soil barrier of landfill cover systems. The effect of geogrid type on the deformation behavior of the soil barrier subjected to various ranges of distortion levels was examined through centrifuge tests carried out at 40 g. An overburden pressure equivalent to that of landfill cover systems was applied to all the soil barriers tested in this study. The performance of the soil barrier with and without geogrid layer was assessed by measuring water breakthrough at the onset of differential settlements during centrifuge tests. Un-reinforced soil barriers of 0.6 m and 1.2 m thickness were observed to experience single narrow cracks penetrating up to full -depth of soil barriers at distortion levels of 0.056 and 0.069 respectively. In comparison, soil barriers reinforced with geogrids restrained cracking better than unreinforced soil barriers. However, degree of restraining of cracks in the soil barriers was found to be strongly depending on the geogrid type and the thickness of the soil barrier. Limiting distortion levels for 0.6 m and 1.2 m thick soil barriers reinforced with a low strength geogrid was found to be 0.095 and 0.108 respectively. When the soil barrier of both thicknesses was reinforced with a geogrid having relatively high tensile load-strain characteristics, the integrity of the geogrid reinforced soil barrier was observed to be retained even after inducing a distortion level of 0.125. The results from the present study suggest that the hydro-mechanical behavior of the soil barriers can be improved with a suitable geogrid layer having adequate tensile load-strain characteristics.     

湿润气候区固废堆场封场土质覆盖层性状研究

固废堆场封场土质覆盖层由天然非胀缩土料组成,其造价及后期维护费用明显低于传统覆盖层,是填埋场封场覆盖的理想型式。采用基于非等温多孔介质中水热耦合运移控制方程的软件,考虑外界气候条件、地表蒸发作用、植被蒸腾作用,建立土质覆盖层–植被–大气相互作用数值模型,针对中国湿润气候区典型城市长期实测气象条件,系统分析了不同结构型式土质覆盖层的性状。分析结果表明,毛细阻滞型覆盖层可把水分阻滞在根系生长层,便于植被蒸腾作用的提取,其性能优于单一土层型覆盖层。土质覆盖层内水分的排出主要依靠植被蒸腾和地表蒸发,二者与植被特征相关,植被条件越好则腾发总量越大;根系生长区内的含水率变化幅度大于其它区域。在本文气候条件下,选择厚度为1.4 m的毛细阻滞型覆盖层并结合一定植被条件可防止产生深层渗漏。     

大厚度湿陷性黄土隧道现场浸水试验研究

对于穿越大厚度湿陷性黄土地层的隧道,其围岩湿陷变形会威胁隧道结构的稳定性。为了分析黄土围岩湿陷变形对隧道衬砌结构的影响机制,选取典型大厚度湿陷性黄土隧道场地,通过开展隧道场地地面浸水试坑试验及隧道仰拱浸水试验,测试了地面入渗和隧道基底入渗过程中不同埋深地层的湿陷沉降变形及地基的沉降变形、入渗过程中围岩的体积含水率变化分布、试坑周边地层的侧向位移、衬砌结构接触压力和轴力,研究了既有隧道黄土地层的湿陷变形特性及水分运移规律、隧道结构力学响应。结果表明,隧道开挖、衬砌作用扰动黄土结构,增大了围岩及深层黄土的渗透性;与天然黄土场地试坑浸水入渗比较,增大了竖向浸水范围,减小了水平向浸水范围。隧道围岩湿陷变形改变了围岩与衬砌结构的相互作用性状。围岩湿陷和地基软化作用增大了二次衬砌结构侧墙竖向荷载和侧墙围岩的挤压作用,引起拱脚地基承载力减小和沉降变形发展,拱顶、拱肩接触面呈受拉状态;仰拱中部地基土的抗力作用抑制其沉降变形,从而使得拱脚和仰拱中部出现显著的沉降差,导致仰拱混凝土开裂,形成纵向裂缝。此外,浸水范围内黄土的湿陷变形不仅引起竖向沉降变形,还会引起周围土体产生侧向水平位移;洞口边坡场地黄土的湿陷性和地层湿陷变形差异较大,反映了黄土山岭黄土场地地层条件复杂多变的特征。