废旧轮胎加筋土研究进展综述

废旧轮胎回收利用于岩土工程回填领域取得了一系列理论和试验成果。根据国内外大量文献,综述了利用废旧轮胎改良砂土、膨胀土、黄土、黏土的研究进展。总结了不同掺量、不同粒径的轮胎在改良不同土质过程中的作用机理和效果。文献表明:粒径较大轮胎块的掺入在剪切面之间发挥了其本身固有的特性,增加了混合体的抗剪强度,而橡胶颗粒掺入土中是通过改善接触面上的摩擦特性增强土的剪切强度。轮胎与不同土体混合作为轻质土工材料用于岩土工程和路基工程,能够很好地改善土体强度、弹性性能、压缩性能。有关废旧轮胎在改良不同土的抗剪强度过程中的疲劳性、老化性和其对环境的影响仍需要进一步研究。     

轮胎条改良黄土剪切强度与体变特性试验研究

为了探究轮胎条尺寸效应及掺量对西北地区黄土剪切力学特性、变形特征影响,寻找体应变与剪切强度关系。通过室内大型直剪试验,研究了轮胎块-黄土混合土剪切过程中的力学和变形特性,研究结果表明轮胎条加筋土抗剪强度特性除与轮胎条的掺量、外观比及尺寸大小有关外,还与黄土的的密度及正应力等因素有关。试验发现轮胎条、黄土两种介质的相互影响发挥了混合体的强度效应,轮胎条的掺入改良了黄土的性质,改善了接触面上的摩擦特性。从试验上证实废弃轮胎改良块黄土效果较为显著,为黄土改良及减少黄土引起的工程地质灾害开拓了一个新的方法。     

纤维加筋土工程性质国内外研究进展

纤维加筋是一种新型土壤性能改良技术,它是指将土体与纤维均匀地混合,以改善土壤的工程性能。本文凭借国内外学者在纤维加筋土技术、性能及应用方面研究经验,对纤维加筋土的强度特性、变形特性等工程特性及纤维加筋土技术的应用研究进行总结。阐述了近年来国内外纤维加筋土的研究进展,并基于现阶段纤维加筋土的理论及技术研究方面的不足,对今后该领域的研究重点和发展方向进行了展望。     

轮胎-土复合体结构性能机理的研究

提出轮胎-土的新型复合结构,为研究其力学特性及工作机理,先通过轮胎条带试验,验证轮胎材料所具有的力学性质;然后对轮胎-土复合体进行无侧限压缩试验,获得相应复合体的竖向和径向应力-应变关系曲线,推求出各自复合体在一定压缩变形下的无侧限抗压强度值、弹性模量。为废旧轮胎在实际土工工程应用中提供合理的力学参数和参考依据。     

废旧轮胎颗粒二灰土与3∶7灰土的工程性能对比研究

本文利用室内固结试验和直剪试验,通过对比分析废旧轮胎颗粒二灰土和3∶7灰土的密度特性、强度特性、变形特性和湿陷特性,研究探讨了废旧轮胎颗粒二灰土处理湿陷性黄土的工程性能。研究结果表明:随着龄期的增长,废旧轮胎颗粒二灰土的剪切强度不断增加。废旧轮胎颗粒二灰土质量轻,强度较高,变形较小,建议在湿陷性黄土地基处理中推广应用。这不仅解决了废旧轮胎固体废弃物的环境问题,而且为湿陷性黄土地区地基处理的工程实践提供了新思路和新方法。     

钢筋(煤矸石)混凝土网格式加筋土挡土结构强度特性与试验研究

提出了一种新型的加筋土挡土结构---钢筋（ 煤矸石） 混凝土网格式加筋土挡土结构。对该网格式加筋土挡土结构进行了大量模型试验，并进行了强度特性分析。试验及分析表明， 该网格式加筋土挡土结构是一种结构合理、可以应用于实际工程的新型挡土结构。     

H-V加筋土性状的颗粒流细观模拟

正交水平-竖向(H-V)加筋是一种新型的土工加筋技术,在H-V加筋土中除了有传统的水平筋条外,还在水平筋条上设置了竖向齿筋。结合已完成的加筋土三轴试验,采用基于离散元理论的颗粒流软件(PFC2D)对试验进行了仿真模拟,较好地拟合了H-V加筋砂土三轴试验的应力–应变曲线,并通过观测颗粒的受力情况分析了H-V加筋砂土的受力机理。通过引入颗粒流理论,对H-V加筋砂土试样的剪切带形成进行了细观数值模拟,揭示了H-V加筋土中剪切带产生、扩展的渐进破坏规律。     

废旧轮胎橡胶粉在公路工程中的应用

简要介绍了废旧轮胎的用途及回收途径,针对废旧轮胎橡胶粉在道路工程中的应用进行了探讨,阐述了国内橡胶沥青及混合料的发展状况及工艺原理、用途等内容,指出将废旧轮胎再生利用于道路工程效益良好,值得大力推广。     

废旧橡胶混凝土力学性能研究进展

废旧橡胶混凝土是一种新型的复合材料,其不但为废旧轮胎回收再利用提供了高效途径,也改善了普通混凝土的力学性能,而且具有明显的环保效应和工程实用价值.在大量参阅国内外废旧橡胶混凝土研究文献的基础上,详尽介绍了橡胶混凝土静力性能、动力性能和预处理方式等研究内容,对相关研究成果进行了总结分析,提出了研究存在的主要问题和未来研究...     

土工合成材料加筋土柔性桥台复合结构及应用

土工合成材料加筋土柔性桥台复合结构是美国“未来桥梁计划”中针对50多万座面临“更换问题”的中小型单跨桥梁而提出的一种新型技术，是土工合成材料加筋土柔性桥台技术的优化与提升。这种新型技术整体性好，可彻底避免传统桩承桥台与引道路基之间的差异沉降，近10年来已逐步在美国各州推广应用。在我国，尽管加筋土理论和技术应用取得了很大发展，但尚无真正的加筋土柔性桥台复合结构的工程实践方面的报道。文章收集了已有的加筋土柔性桥台复合结构工程案例和现场监测成果，整理归纳其结构特点和工作特性，结果表明：该结构通常具有统一的结构形式和技术特点，如加筋间距一般为0.2m、面层型式一般为模块式等；该结构具有施工简便快速、造价节省等优点，并表现出工后沉降小等良好的服役性能。     

Experimental investigation of bearing capacity of sand reinforced with randomly distributed tire shreds

A series of laboratory model tests has been carried out to investigate the using of shredded waste tires as reinforcement to increase the bearing capacity of soil. Shred content and shreds aspect ratio are the main parameters that affect the bearing capacity. Tire shreds with rectangular shape and widths of 2 and 3 cm with aspect ratios 2, 3, 4 and 5 are mixed with sand. Five shred contents of 10%, 20%, 30%, 40% and 50% by volume were selected. Addition of tire shreds to sand increases BCR (bearing capacity ratio) from 1.17 to 3.9 with respect to shred content and shreds aspect ratio. The maximum BCR is attained at shred content of 40% and dimensions of 3 × 12 cm. It is shown that increasing of shred content increases the BCR. However, an optimum value for shred content is observed after that increasing shreds led to decrease in BCR. For a given shred width, shred content and soil density it seems that aspect ratio of 4 gives maximum BCR.     

Multifaceted potentials of tire-derived three dimensional geosynthetics in geotechnical applications and their evaluation

Scrapped tire-derived materials, such as tire chips and tire shreds, can be categorized as three dimensional geosynthetics. This paper introduces recent Japanese experience in geotechnical related applications of geosynthetics that focus mainly on tire chips and tire shreds. Three specific applications of tire chips and tire shreds are introduced here. They are: (1) tire shreds to improve drainage; (2) sand-mixed tire chips to mitigate earthquake damage; and (3) tire chips mixed with cement-treated clay to improve toughness and ductility. The developed techniques related to these applications, verification through model testing, as well as element testing and the field applications are presented. It was observed that tire shreds can maintain high permeability even under a high compressive load. When tire chips and/or sand-mixed tire chips are used as a compressible cushion, not only the dynamic load against a structure but also the dynamically induced permanent structural displacement could also be significantly reduced. On the other hand, mixing tire chips with cement-treated clay gives toughness to the geomaterial, and thus provides resistance against the development of cracks during deformation. In addition, an X-ray CT investigation of deformation behavior of such materials demonstrated the success of using cement-treated clay with tire chips as a sealing material to protect leakage of contaminated materials at a waste disposal site in Tokyo bay area.     

Interaction between geogrid reinforcement and tire chip–sand lightweight backfill

This paper deals with the interaction between the geogrid and the tire chip–sand mixture including the determination of the index properties of the backfill materials, the shear strength parameters, the interaction coefficients, and the efficiency of geogrid reinforcements in tire chip–sand backfills. Numerous experiments including index tests, compaction tests, pullout tests, and large-scale direct shear tests were conducted. Saint–Gobain (geogrid A) and Polyfelt (geogrid B) were selected as reinforcing materials. Tire chip–sand mixtures with mixing ratios of 0:100, 30:70, 40:60, and 50:50 by weight were used as fill materials. The test results revealed that the dry unit weight of tire chip–sand mixtures depended more on the sand content, and less on the water content. The mixture at the mixing ratio of 30:70 by weight or 50:50 by volume was found to be the most suitable fill material compared to other mixing ratios. The pullout resistance and the pullout interaction coefficients of geogrid A were slightly higher than those of geogrid B. In contrast, in the direct shear resistance, the direct shear interaction coefficients, and the efficiency values of geogrid B were slightly higher than those of geogrid A. Since geogrid B has the needed uniaxial reinforcement properties and its sufficient interaction characteristics with tire chip–sand mixture, the geogrid B was utilized in this study. The interaction coefficients between the tire chip–sand backfill with 30:70 mixing ratio by weight were found to be 0.71 in pullout mode and 0.92 in direct shear mode for geogrid B.     

基于热探针测试的橡胶-砂颗粒轻质混合填料#br# 导热系数影响因素研究

导热系数是岩土材料热学特性的一个重要参数,文章对橡胶-砂颗粒混合物的进行了大量的热针试验。详细分析含砂率、含水率和干密度对导热系数的影响。结果表明：当含砂量小于20%时,橡胶-砂混合物的导热系数逐渐增加,但砂粒含量超过80%后,导热系数立即出现较高的增加速率;随着干密度的增加,导热系数在低含砂率时呈现抛物线增长,在高含砂率时呈现线性增长;橡胶-砂混合物导热系数随含水率的变化可分为增长区域和稳定区域,6%含水率可作为临界含水率。该文可为地热相关结构周围的轻质回填材料提供更合理的热学参数,此外,废旧轮胎的有效利用可以减少环境污染,促进可持续的基础设施。     

Examination of earth pressure reduction mechanism using tire-chip inclusion in sandy backfill via numerical simulation

Tire chips have special features as geomaterials, as they are lighter than soil particles, highly compressible, and softer than sand. In this study, the effect of tire chips used as a compressible inclusion in backfill on the load reduction against retaining walls is numerically investigated. It is known that a reduction in earth pressure in backfill is realized by achieving a quasi-active or intermediate active state; and thus, a field test of this behavior is herein numerically simulated. The influence of the Poisson’s ratio and elastic modulus of tire chips on the reduction in earth pressure against retaining walls is examined by assuming that tire chips can be modeled as an elastic body. The numerical simulation reveals that the attainment of the active state in sandy backfill is primarily due to the light-weight nature of tire chips, along with their low Young’s modulus and Poisson’s ratio. Furthermore, the influence of friction at the bottom of the backfill mass is also considered, and the earth pressure reduction mechanism incorporating this factor is also numerically investigated.     

压电陶瓷传感器在岩土工程中的应用

压电陶瓷传感器在岩土工程中有很多应用,尤其是通过测量波速来确定土的性质方面。由于材料的物理性质与波速密切相关,压电陶瓷传感器提供了一种简便可靠的无损检测方法。本文报道了压电陶瓷传感器应用于粘土、砂和砾石等不同种类土的研究成果,对应力导致土体各向异性的研究,对路基和地基土的力学特性检测,在离心模型试验中的应用,以及在微重力环境下的粒状材料中波的传播特性的研究等。研究表明,压电陶瓷传感器在岩土力学研究和工程实践中有广阔的应用前景。     

Geotechnical Properties of a Pumice Sand

The pumice sand found in the North Island of New Zealand has properties which lie beyond those usually associated with cohesionless soils. The grains are very soft and the sand has a high void ratio, thus forming a compressible material. This paper presents the results of a series of drained triaxial and K₀ tests on dry pumice sand. The tests were conducted to evaluate the geotechnical properties, particularly the critical state parameters, of the sand and also to provide background information for interpretation of cone penetration tests in the material. The K₀ tests were used to evaluate the compression envelope under conditions of no lateral strain and to determine values of constrained modulus. Significant grain crushing was found to occur during testing even at low confining stress, in fact the stress-strain-strength behaviour of the material is dominated by particle crushing. Routine soil testing techniques were found to be inadequate for the evaluation of the specific gravity of pumice sand particles and a different technique was used for this purpose. The angle of friction of pumice sand was found to be larger than that of quartz sands, however pumice sand required very large shear strains to mobilise the peak and critical state shear strength and, for several tests, critical state conditions were not reached.     

砂土介质中薄膜压力传感器的标定试验研究

土压力的精确测量在岩土工程领域有重要作用。传统土压力盒体积大,对土体完整影响较大,薄膜压力传感器是一种新型测量土压力的仪器,厚度薄、灵敏度高。薄膜压力传感器应用过程中需要根据实际使用情况进行标定。本文通过自主研制的标定筒研究薄膜压力传感器在砂土介质中的标定效果,并将砂标结果与厂标结果进行对比。采用同一薄膜压力传感器对不同相对密度的砂土进行了标定,结果表明,砂标结果值大于厂标结果值,砂土的相对密度越大,标定系数越小。     

Some properties of A sedimentary laterite soil as engineering construction material

A sedimentary laterite soil is examined for its suitability as a construction material by the consideration of its mineralogy and basic geotechnical properties as well as its consolidation and permeability in the compacted state. Three compaction energy levels are utilised. Mineralogically, the soil contains virtually nothing undesirable while its basic geotechnical properties are those generally ascribed to non-problematic soils. The compressibility of the soil varies from moderate to low depending on the energy of compaction. It is however impervious for all the compaction energy levels. The sedimentary laterite soil constitute a good engineering construction material as it has already been successfully used as base and sub-base material in road construction. Results obtained in this study show that this laterite soil is also suitable for use as fill materials in embankment and dam construction.     

玻璃砂透明土变形特性三轴试验研究

玻璃砂透明土是一种由玻璃砂、正十二烷和15号白油按质量比1∶4的混合液体制备而成的新型人工合成透明土;该材料具有透明度高,与天然土体相似度更好等优点,可以用于基于透明土材料的可视化模型试验。为了研究其变形特性,对不同级配的玻璃砂透明土,进行三轴固结不排水剪切试验和三轴固结排水剪切试验,并与同等条件下的福建标准砂试验结果进行对比分析;测得固结不排水剪应力-应变曲线、以及孔压应变曲线形态等工程特性。试验结果表明,随着相对密度的增加,玻璃砂的应力-应变关系从应变硬化型向应变软化型过渡,破坏时的孔压系数A_f降低,变形模量变大;与标准砂相比,玻璃砂透明土的应力-应变曲线峰值来的相对更慢一些。