浅谈路基工程中铺设土工合成材料的施工技术

铺设土工合成材料对软弱地基路堤进行加强处理具有造价低、工艺简单、效果好的特点。本文针对土工格室、土工格栅、土工编织布三种土工合成材料的作用、技术性能及施工方法进行了简要的阐述。     

土工格室对路堤沉降影响的有限元分析

通过研究土工格室如何对软土路堤进行加筋,并且应用ANSYS有限元软件来数值模拟土工格室增强土体的强度。通过添加土工格室前后情况对比,改变土工格室的添加层数进行分析,研究了铺设土工格室对软土路堤的沉降影响以及最优的铺设层数。结果表明,添加土工格室能限制路堤的沉降,使土体稳定性整体提高。     

软土地基加筋土路堤变形及稳定性分析

软土地基加筋土路堤进行了数值模拟,分析了筋材类型和加筋方式对路堤变形及稳定性的影响。研究结果表明:在软土地基和路堤之间铺设土工格栅可以有效提高路堤稳定性;增加路堤加筋层数不如增加底层筋材力学指标对路堤稳定性的影响效果明显;在固结过程中,加筋土路堤对地基侧向位移影响深度约为2H(H为路堤高度),研究成果对软土地基加筋土路堤的设计和施工具有指导意义。     

土工合成材料施工损伤问题的探讨

土工合成材料加筋砂、石垫层是在基础下有效深度范围土体内铺设土工合成材料，通过土工格栅、土工织物等加筋材料与砂、石间的相互作用，可提高地基承载力和稳定性，这种地基处理方法因具有施工简便、无污染、造价低、工期短等优点而广泛应用。     

桩承土工合成材料复合地基的研究

介绍了桩承土工合成材料复合地基的作用机理 ,应用改进的太沙基原理 ,分析了土工复合材料复合层地基承载力的计算 ,并通过在连霍高速公路三门峡～灵宝段软基处理中应用的工程实例验证 ,桩承土工合成材料复合地基可加速软土地基固结 ,提高路基路堤稳定性 ,加快填筑速率 ,缩短工期。     

一种考虑土工织物抗滑作用的稳定分析方法

本文分析了荷兰法和瑞典法的优缺点，指出了土工织物界面摩擦力对稳定的影响，提出了应用有限元法和荷兰法或瑞典法相结合验算铺设土工织物的路堤稳定性的方法。     

基于MIDAS的复合地基加筋垫层的力学特性模拟分析研究

为优化复合地基加筋垫层设计,在处理吹填软土地基时提供理论依据,通过MIDAS有限元软件对加筋复合地基数值模拟,对复合地基加筋垫层的力学特性进行分析,并对加筋方案、加筋层数进行设计优化.结果表明,地基上部荷载较小(100kPa),加筋垫层作用不显著;上部荷载较大时(250kPa),复合土工格栅的作用发挥较充分,加筋层数成为影响桩土应力比的主要因素,为加筋垫层设计优化提供可靠的理论依据.最后,铺设2层复合土工格栅控制沉降变形较铺设1层的效果好,铺设3层则效果提升不大,综合经济和施工便利的因素,垫层中铺设2层复合土工格栅最优,加筋材料的优化层间距为3.3cm.     

土工格栅加筋路堤的机理分析及其应用

目前,土工格栅加筋路堤的方法在高填方路堤工程中正获得越来越多的应用。本文首先分析了土工格栅加筋路堤的机理,包括三个方面的因素:承担水平荷载,提高地基土承载力;增大地基土的约束力,提高竖向承载力;抑制土拱效应,减小路基沉降量。然后以某土工格栅加筋在公路路堤工程中的应用为例,论述了该技术的施工流程、技术参数、施工要点和质量控制等,表明了土工格栅具有较高的工程应用价值。     

土工格栅加固斜坡路堤的数值模拟

土工格栅具有强度高、延伸率低等特点,在路基适当位置铺设土工格栅可有效改善路堤应力环境,减小沉降和侧向变形。通过数值模拟方法研究了铺设土工格栅前后路堤水平位移、垂直位移的变化。计算结果表明,土工格栅对路堤的水平位移和垂直位移起到了较好的抑制作用,对水平位移的抑制作用更为明显;加筋层数对路堤变形的影响较小,多层加筋的效果和一层加筋相比并不明显。研究成果对路基工程设计具有一定的参考价值。     

格栅模量对加筋软基路堤关键位移的影响

为了研究土工格栅模量对加筋软土地基上路堤顶面不均匀沉降、路堤中心沉降、坡脚水平位移三个关键位移的影响,通过工程实例现场观测与有限元数值试验相结合的方法,分析了采用不同模量土工格栅加筋后软土地基上的路堤关键位移。研究了土工格栅模量对路堤关键位移的影响。研究成果表明：合理的选择土工格栅的模量可以有效的控制路堤的关键位移。有限元数值试验与现场观测结果一致,其结果可以作为软基加筋路堤设计参考。     

浅谈土工格室在高速公路施工中的应用

土工格室在公路建设中的应用日趋广泛。在处理软弱地基、排水、路基护坡、桥头跳车等方面都有很成功的应用。与其它土工合成材料相比是一种新型的、具有更多的优越性、实用性强、价格适宜、应用效果很好的公路建设新材料。文章结合邵怀、岭南两条高速公路建设实践。介绍了土工格室在公路施工中的应用。     

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.     

土工合成材料双向拉伸多功能试验机的研制及初步应用

为揭示土工合成材料双向拉伸状态下的力学特性,自主研制了一台双向拉伸多功能试验机,能够进行瞬时和长期蠕变双向拉伸试验。瞬时拉伸采用电机控制,可以实现两个方向任意比例下应力和应变加载;蠕变拉伸采用法码加载,可同时进行3组大变形蠕变拉伸试验。经初步应用表明,该试验机能够进行复杂应力、应变路径下土工合成材料双向拉伸试验,为土工合成材料双向拉伸力学特性的研究提供了一种科学有效手段。     

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.     

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。     

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。     

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.     

铁路路基工程的现场试验检测

铁路路基的施工质量关系到整个工程的质量、进度和列车运行安全,而运用科学的试验检测方法是保证路基工程施工质量的重要措施之一,本文从路基工程现场试验检测的角度论述了用不同的检测方法对路基工程质量的控制.