土工合成材料在废弃物填埋场中的应用

介绍了国内外废弃物处理的现状和土工合成材料在废弃物填埋场中应用的情况。废弃物填埋场中所使用的土工合成材料包括土工膜,非织造土工织物和土工格栅,这些土工合成材料可起到密封隔离,排水,过滤,排气和加固填埋场边坡的作用,最后展望了土工合成材料在不保领域中广阔的发展前景。     

国内岩土工程业近10年来发展成熟的技术统计(三)

15 土工合成材料应用技术 (1)主要技术内容 土工合成材料是一种新型的岩土工程材料,分为土工织物、土工膜、特种土工合成材料和复合型土工合成材料等种.     

土工合成材料加筋的试验研究

以 6种不同种类的国产土工合成材料为加筋材料 ,即针刺无纺土工织物、涤纶纤维经编土工格栅、玻璃纤维土工格栅、单向塑料拉伸土工格栅、双向塑料拉伸土工格栅和土工网 ,进行三轴试验比较各种土工合成材料对砂的加筋效果 ;进行直剪试验和拉拔试验比较各种土工合成材料与填料 (砂和石灰粉煤灰 )的界面作用特性 ,得到一些有益的结论 ,可指导土工合成材料的优选和研究土工合成材料的加筋机理。     

土工合成材料技术的发展与应用

伴随着土木工程技术的进步,土工合成材料技术已经成为重要的土工加固技术之一。本文以土工合成材料为研究对象,结合该材料在国内外的应用情况,综述了土工合成材料技术在土木工程建设中的发展与应用。     

聚苯乙烯泡沫塑料的测试及其在土工中的应用

<正> 一、引言土工合成材料(Geotextile)的应用,国内外均很普遍。国际上已召开了四届土工合成材料学术讨论会,我国也已分别在天津和沈阳召开了两届有关会议,对土工合成材料的发展和应用起到了极大的推动作用。同时,土工合成材料的新品种也不断出现,其中聚苯乙烯泡沫塑料(Expanded polystyrene,简称EPS)是令人注目的品种之一,它的出现使得土工中原来难以解决的问题获得了令人满意的解决办法。1972年挪威道路研究所首次将1m厚的普通填料层换成聚苯乙烯板,成功地遏止了与桥台连接路堤的过渡沉陷,从而使EPS开创了在土工中     

土工合成材料加筋砂土三轴试验研究

本文以 5种国产土工合成材料为加筋材料 ,它们分别是针刺无纺土工织物、涤纶纤维经编土工格栅、玻璃纤维土工格栅、聚丙烯双向土工格栅和聚乙烯土工网 ,用三轴试验比较各种土工合成材料对砂土的加筋效果 ,得到一些有益的结论 ,可指导土工合成材料的优选和研究加筋机理 ,同时指出部分国产土工合成材料产品的不足。     

土工合成材料在三峡库区库岸防护中的应用可行性研究

介绍了土工合成材料的种类及其功能,进而简单介绍了土工合成材料在库岸防护工程中的应用现状;然后在详细分析了重庆市万州区鞍子坝库岸段工程地质条件的基础上计算了堆积体沿基岩面滑动的稳定性,并分析了库岸的破坏形式;最后对库岸防护采用加筋土进行了初步设计并对设计从外部稳定性(地基承载力、抗滑稳定性、抗倾覆稳定性)和内部稳定性(土工格栅强度和抗拔稳定性)进行了验算。研究结果认为利用土工合成材料对库岸防护完全可行。     

浅谈土工格栅在公路工程中的应用

对塑料土工格栅、玻纤土工格栅和经编土工格栅的性能做了比较,对三种土工格栅的应用进行了总结,并对目前公路工程中的加筋选材问题提出了一些观点,以利于土工合成材料加筋技术在具体工程中的应用.     

土工合成材料加筋土挡墙的工程应用

介绍土工合成材料加筋土挡墙的设计方法及土工格栅加筋土挡墙工程实例 ,对推动土工合成材料加筋土技术的工程应用具有一定意义。     

浅谈土工合成材料在路基边坡防护中的应用

实践表明,一种新型的土工合成材料主要有：土工织物、土工薄膜、复合型土工合成材料、特种土工合成材料等,在应用于竖直挡土墙及陡坡等的排水系统、加固、大坝、侵蚀控制等方面后,则明显改善了路基边坡的稳定性,提升了路面质量。     

Electrokinetic geosynthetics in hydraulic applications

In use most geosynthetics play a passive role. New applications for geosynthetics have been identified if they can provide an active role, initiating biological, chemical or physical change to the matrix in which it is installed as well as providing the established functions. This can be achieved by combining the electrokinetic phenomena of electro-osmosis, electrophoresis and associated electrokinetic functions such as electrolysis with the traditional functions of geosynthetics of drainage, filtration, containment and reinforcement to form electokinetic geosynthetics (EKG). Electrokinetic geosynthetics can be made singly or from combinations of woven, non-woven, needle punched knitted, extruded or laminated materials and can be formed in any 2D or 3D shape.The majority of the uses of EKG are in hydraulic applications or applications with a significant hydraulic component. These can be grouped in separate engineering categories such as civil, mining, and water engineering. The concept of electrokinetic geosynthetics is described and details of applications and case studies are provided in the paper.     

A multi-camera based photogrammetric method for three-dimensional full-field displacement measurements of geosynthetics during tensile test

Conventional methods for measuring the deformational response of geosynthetics, such as the linear variable differential transformers (LVDTs), strain gauges, and extensometers have several limitations in fully determining the complete strain distribution in geosynthetics. This paper presents a multi-camera based photogrammetric method to track the 3D full-field displacements of geosynthetics during tensile tests. The proposed method extends the conventional one-camera based photogrammetry for static object measurements to multi-camera-based photogrammetry for object measurements with continuous movements or deformations. It is non-contact, cost-effective, highly accurate, and capable of measuring the 3D full-field displacements of the geosynthetics. A tensile test on a geogrid specimen was performed to verify the effectiveness and accuracy of the proposed photogrammetric method. The results from the tensile tests using both the proposed method and conventional methods, such as machine-controlled displacement measurements and extensometer, were presented and compared. It was observed that the average absolute difference between the proposed photogrammetric method and the machine-controlled movements of the bottom clamp was 0.25%, and the average absolute error was 0.038 mm. The average difference in measurements made by the proposed method and extensometer was 0.07%. It was further found that the proposed method can provide more comprehensive input, such as the complete strain and modulus distributions in the geosynthetics, for a probability-based geosynthetics design.     

加筋土结构中筋材拉拔力的分布规律研究

分析了加筋材料在拉拔试验条件下,筋材所受到的拉力、剪应力、应变之间的关系,利用筋土界面间存在的抗剪刚度系数G,建立起了与材料拉伸模量E_r和G有关的拉拔影响系数α,从而推导出拉力沿筋材分布的公式和各点筋土的相对位移公式。通过与已有的试验数据相对比,证实该公式的可行性。分析了拉力在筋材上的传播规律和α对筋材拉拔力分布的影响,表明用α能综合反映压应力、摩阻力、土体性质等多种因素对筋材拉力的影响。在加筋土结构中,筋材位移不是很大时,采用该公式能较好地估算筋材各处的拉力。     

Landfill side slope lining system performance: A comparison of field measurements and numerical modelling analyses

Low permeability engineered landfill barriers often consist of a combination of geosynthetics and mineral layers. Even though numerical modelling software is applied during the landfill design process, a lack of data about mechanical performance of landfill barriers is available to validate and calibrate those models. Instrumentation has been installed on a landfill site to monitor multilayer landfill lining system physical performance. The lining system comprises of a compacted clay layer overlaid by high density polyethylene geomembrane, geotextile and sand. Data recorded on the site includes: geosynthetic displacements (extensometers), strains (fibre optics, Demec strain gauges, extensometers) and stresses imposed on the liner (pressure cells). In addition, temperature readings were collected by a logger installed at the surface of the geomembrane, at the clay surface using pressure cell thermistors and air temperature using a thermometer. This paper presents readings collected throughout a period of three years and compares this measured performance with the corresponding numerical modelling of the lining system for stages during construction. Numerical modelling predictions of lining system behaviour during construction are comparable with the measurements when the geosynthetics are covered soon after placement, however, where the geosynthetics are left exposed to the sun for an extended period of time, in situ behaviour of the geosynthetics cannot be replicated by the numerical analysis. This study highlights the significant influence of the effect of temperature on geosynthetics displacements. A simple thermal analysis of the exposed geosynthetics is used to support the explanation for observed behaviour.     

Creep behaviour of geosynthetics

Empirical results dealing with rheological properties of some geosynthetics are presented. Creep tests performed on some Polish-made geotextiles are described and discussed within the framework of the standard linear solid (SLS) model. It is shown that the SLS model described by three parameters can serve as a useful low resolution approximation for a range of geosynthetics, for low stress levels which exclude secondary and tertiary creep. The parameters of the SLS model were determined by curve fitting for three types of Polish geotextiles as well as for some other geosynthetics. The problems of creep under increasing load and creep after partial unloading are discussed. Two modified rheological models of geotextiles, which take into account the plastic strains, are proposed.     

筋箍长度及刚度对加筋碎石桩复合地基承载力影响分析

针对加筋碎石桩复合地基中桩体性能,通过有限元数值模拟与模型试验对比分析,验证了数值模型的可靠性,进而变换加筋长度,研究分析了复合基础下端承加筋单桩与群桩的极限承载能力和破坏模式。研究结果表明:筋材强度较低时,加筋长度不会对桩体破坏模式产生影响,对极限承载能力提高有限;随着筋材强度不断提高,碎石桩在加筋体以下区域发生剪切破坏,并且随着加筋长度的增加向更深土层发展,基础的极限承载能力线性增长。加筋长度对群桩复合地基不同位置处桩体的破坏模式影响不同。相较于边桩,中心桩在桩身较深位置处发生剪切破坏,筋材需达到较深的长度才发挥约束效果。     

Soil–geosynthetic interaction: Modelling and analysis

Interaction between soils and geosynthetics is of utmost importance in applications of these materials as reinforcement in geotechnical engineering. That is also the case for some applications of geosynthetics in environmental protection works. The mechanisms of soil–geosynthetic interaction can be very complex, depending on the type and properties of the geosynthetic and the soil. This paper presents and discusses some experimental, theoretical and numerical methods for the study and evaluation of interaction between soils and geosynthetics, with particular reference to the applications of these materials in soil reinforcement. The main advantages and limitations of some traditional experimental and theoretical methods for the study of soil–geosynthetics interaction are presented and new applications of these methods are addressed. The need for improvements in experimental and theoretical techniques for a better understanding of soil–geosynthetic interaction is highlighted.     

土工合成材料与土界面的细观研究

利用颗粒流程序（PFC2D）对土工合成材料的拉拔试验进行模拟,着重从细观角度来分析土工合成材料与土的接触界面。通过室内拟合试验,选取和校准离散元的细观参数,土工合成材料用平行黏结模拟,土颗粒采用由3个圆形颗粒组成一个椭圆形团进行数值模拟。数值模拟结果表明,接触界面的厚度为6～7倍平均土颗粒直径,接触界面中的颗粒发生较大相对位移,孔隙率增大,接触数减小。PFC2D为从细观角度研究土工合成材料与土的接触界面特性的理想工具。     

土工合成材料处治老路路基拓宽的数值分析

随着交通量的日益增加，老路拓宽已经成为公路建设非常重要的～种手段。为减少老路拓宽新老路基不均匀沉降，提高路基整体稳定性，土工合成材料在新老路基结合部处治中获得很大的成功。针对老路拓宽时采用土工合成材料处治结合部的特点，将新老路基、路面结构作为整体，建立数值模型。采用FLAC进行分析，主要从路基位移、路基项面应力及土工合成材料拉力分布等方面，研究土工合成材料处治新老路基结合部的作用机制，分析不同加筋层数和不同路基填土高度下的处治效果。计算结果表明，采用土工合成材料不仅可以有效地减小路基顶面的差异沉降和水平位移，而且使得路基反射到路面的平均应力更小且分布均匀。