【作者】 王昊；

【导师】 张宏博； 宋修广；

【作者基本信息】 山东大学 ， 建筑与土木工程（专业学位）， 2022， 硕士

【摘要】 随着我国交通运输业的快速发展,废旧轮胎数量激增。废旧轮胎作为一种“黑色污染”,有滋生细菌、引发火灾、占用土地等危害,对社会公众安全造成了严重的影响,亟需进行资源化利用。国内外学者研究表明,废旧轮胎条带/格室作为一种加筋材料具有良好的界面摩擦特性与耐久性,适用作粗粒料、细粒土及腐蚀性土质的加筋改良。同时,研究表明在对于粉土等细粒土路基的土工加筋工程中,由于粉土自身强度较低,易液化,压实困难等问题,土工加筋在细粒土填料中的效果并不显著。因此,本文针对黄泛区粉土路基易发生遇水湿化、土工格栅加筋效果不良等工程问题,为了提高其整体性及抗变形能力,研究提出将轮胎衍生集料(Tire Derived Aggregate,TDA)材料按一定比例掺入粉土中改变颗粒级配,形成路基复合填料以提高路基土抗剪强度,并采用废旧轮胎条带作为路基加筋材料以提高路基整体性的新型加筋技术方案。为探究该技术的可行性和应用效果,本文基于室内试验、细观尺度数值模拟和理论分析,探究了 TDA-粉土复合填料的工程特性与力学强度提高机理,揭示了复合填料中TDA碎片对粉土的加筋机理与加筋效果,并在此基础上建立了拉拔峰值拉拔力计算方法,为该技术的推广应用提供了理论依据。依据研究成果,主要得到如下主要结论:1.TDA-粉土复合填料的击实试验及三轴试验表明,复合填料的最优含水率及最大干密度随TDA掺入比的增加而降低,但抗剪强度随TDA含量的增加而增长。基于宏观尺度的试验建立了 0%-15%TDA掺量复合填料抗剪强度的预估方法。细观尺度颗粒流数值模拟表明,TDA粗粒料的掺入对粉土的剪切破裂面产生了阻断作用,有效提高了土体抗剪强度。2.废旧轮胎条带室内拉拔试验表明,通过向粉土中加入TDA材料可以有效的改善废旧轮胎条带在填料中的摩擦特性,粉土-轮胎条带的界面摩擦角可从39.70°提高到45.95°。同时,当条带设置加强肋时,可以显著的提高轮胎条带的拉拔力,最大可提高拉拔承载力2.3倍左右。填料含水率对废旧轮胎条带的极限拉拔力有一定的影响,含水率的增加会引起废旧轮胎条带极限拉拔力的降低。结果验证了复合加筋对筋材抗拔阻力的提升效果,并证明了加强肋技术的优势。3.为揭示TDA-粉土复合填料中废旧轮胎条带的拉拔承载机理,采用颗粒流数值模拟分析,探讨了不同条带类型与加强肋参数对拉拔承载力的影响。结果表明,对于无肋条带,其拉拔力受控于界面摩阻力;对于带肋轮胎条带,其拉拔力受控于加强肋,加强肋端阻力约占总拉拔力的60%以上,且加强肋的高度、个数、间距、结构形式等因素会对条带的拉拔承载力产生影响。基于数值模拟结果,考虑端阻力与界面摩阻力的折减效应及复合填料中TDA颗粒的影响,构建了 TDA-粉土复合填料中废旧轮胎条带极限拉拔力计算公式,可以为对加强肋型轮胎的设计计算提供理论依据。更多还原

【Abstract】 With the development of the transportation industry in China,the number of waste tires had increased dramatically.Known as a kind of ’black pollution’,the existence of waste tires had caused severe impacts on social and public security,thus,it is needed for it to be made for resource utilization.Present research had revealed that waste tire strips/geocells can be utilized as a new kind of reinforced material for well interface friction and good durability.These properties made the reinforced material suitable for reinforcement projects in coarse-grained soils,silt,or corrosive soils.At the same time,the research shows that in the embankment reinforcement projects,the reinforcemnet effect was usually unsignificant due to the liquefaction,compaction diffculties and low strength of fine grained soils.Therefore,aimed at the problems of water-induced deformation and insufficient reinforcement in silt subgrades,in order to improve the integrality and deformation resistance of the subgrades,A new utilization method of waste tires in transportation geotechnics had been proposed by combining Tire Derived Aggregates(TDA)mixed with silts to obtain the mixed material to improve the strength of subgrade,along with waste tire strips as reinforcement material.In order to examine the feasibility and function of the proposed reinforce method,based on indoor tests,numerical simulation,and theoretical analysis,the engineering properties and the mechanism of improvement of the TDA-silt mixture had been studied.Then,the pullout behavior of tire strips was studied,and the mechanism of the reinforcement,along with the calculation method of pullout resistance was established based on mechanism studies.The obtained results could provide theory and experiment references for design and actual engineering applications.Based on the research outputs,the following conclusions can be made:1.The compaction and triaxial shear tests showed that when tire content(in mass)was between 0%and 15%,the optimum moisture content(OMC)and maximum dry density(MDD)of TDA-silt composite decreased with the increment in TDA content,while the overall shear strength increased with the increase of TDA content.The estimation method of shear strength parameters were proposed based on macro model test analysis.The results of micro analysis showed that the including of TDA material exerted a blocking effect on the shear failure zone of soil samples,thus enhancing the shear strength of the composite.2.The indoor pullout model tests had proved that waste tires had larger pullout bearing capacity in mixtures with large tire contents.The interface friction angle increased from 39.70° to 45.95 °,while the TDA content increased from 0 to 15%.Meanwhile,when the strip is equipped with reinforcement members,the pullout force of the tire strips can be significantly increased,by distributing the reinforcement members reasonably,the pullout capacity could be increased by 2.3 times.Moisture content also had impact on pullout capacity,the increasement in moisture content will cause a reduction in ultimate pullout capacity.The results obtained proved the feasibility of composite reinforcement method and the advantages of the enhancement rib technique was demonstrated.3.In order to determine the pullout resistance and force distribution during pullout,particle flow simulations were conducted.Based on the obtained results,for the unribbed strip,the pullout capacity is influenced by the TDA material content and spatial arrangement,and for the ribbed tire strip,the height,number,spacing and structural form of the enhancement ribs affect the pullout capacity of the strip.The pull-out load capacity in ribbed strip is mainly borne by the reinforced member structure,in most cases,the members bored more than 60 percent of the pullout force,according to simulations.Based on the results of simulation,the estimation equations to calculate the pullout capacity of waste tire strips embedded in TDA-silt composite with the reduction of friction and bearing force into consideration was established.The obtained calculation method could provide theoretical references to the design and application of ribbed tire strips.更多还原