规则排列的轻质球形材料路基应力传递规律研究

发布时间：2019-03-16 16:49

【摘要】：轻质球形材料路基作为一种新型的路基,具有自重轻、强度高、施工快、无需碾压的优点,具有广阔的应用前景。研究轻质球形材料路基内部应力传递规律,对于保证轻质球形材料路基整体稳定性十分重要。轻质球形材料路基内部颗粒具有明显的离散性,传统的土质土力学理论在分析轻质球形材料路基内部应力规律适用性不足。鉴于此,本文从堆积体接触力理论传递模型推导和接触力检测试验两方面,开展了规则排列的轻质球形材料堆积体的接触力传递分布规律研究,主要研究内容和研究成果如下:首先,总结分析了现有轻质球形材料成型模具的缺点,改进设计了轻质球形材料成型模具,确定了与成型模具匹配的轻质球形材料试件室内成型方法。其次,基于静力平衡理论和随机理论,建立了竖向集中荷载作用和竖向均布荷载作用两种条件下,二维整齐排列、二维紧密排列、三维体心立方堆积三种规则排列的堆积体中接触力的理论传递模型,确定了不同排列方式的堆积体中接触力传递的通项公式,并分析了堆积体中接触力逐层传递的分布规律。再次,针对目前的接触力检测方法对轻质球形材料堆积体接触力检测适用性不足的问题,采用称重传感器逐层检测不同堆积层数的堆积体底层球体的接触力的试验方法,得到了竖向均布荷载作用下二维整齐排列、二维紧密排列、三维体心立方堆积三种规则排列的堆积体中接触力的分布规律。分析了接触力分布规律的试验结果和理论结果存在差异的原因,认为球体尺寸的微小差别及加载方式的稳定性是影响试验结果的关键因素;并且,建立了接触力峰值试验值和接触力峰值理论值的线性相关关系,得到了用接触力峰值理论值修正接触力峰值试验值的修正系数,并提出了修正系数的确定方法。最后,采用接触压缩破坏试验方法,确定了轻质球形材料的破坏模式为产生大的塑性变形之后的脆性开裂,认为赫兹接触理论确定的最大拉应力不适合作为单个轻质球形材料的强度准则,提出了以单个轻质球形材料的弹性极限对应的接触力作为轻质球形材料路基最大填筑高度的计算控制标准,并计算得到了路基最大填筑高度,能够满足一般路基的填筑高度要求。
[Abstract]:As a new type of roadbed, lightweight spherical roadbed has the advantages of light weight, high strength, fast construction and no need to be rolled, so it has a wide application prospect. It is very important to study the internal stress transfer law of lightweight spherical roadbed to ensure the overall stability of lightweight spherical subgrade. The internal particles of lightweight spherical material roadbed are obviously discrete, and the traditional soil mechanics theory is not suitable for analyzing the internal stress law of lightweight spherical material subgrade. In view of this, in this paper, from the theoretical transfer model of contact force of accumulative body and the test of contact force, the distribution law of contact force transfer of light spherical material with regular arrangement has been studied in this paper. The main research contents and achievements are as follows: firstly, the shortcomings of the existing lightweight spherical materials forming die are summarized and analyzed, and the lightweight spherical material forming die is improved and designed. The indoor molding method of lightweight spherical material specimen matching with molding die was determined. Secondly, based on the static equilibrium theory and stochastic theory, the two-dimensional neat arrangement and two-dimensional compact arrangement are established under the conditions of vertical concentrated load and vertical uniform load. The theoretical transfer model of contact force in three kinds of regular arrangement of three-dimensional body-centered cubic accumulation is established. The general formula of contact force transfer in different arrangement is determined, and the distribution rule of contact force transfer layer by layer in the accumulation is analyzed. Thirdly, aiming at the lack of applicability of the current contact force testing method to the contact force detection of lightweight spherical materials, a weighing sensor is used to detect the contact force of the bottom sphere of the accumulative body with different stacking layers one by one, and the test method is used to test the contact force of the bottom sphere of the accumulative body with different number of stacking layers. The distribution rules of contact forces in three regular arrangements of two-dimensional, two-dimensional compact arrangement and three-dimensional body-centered cubic accumulation under vertical uniform load are obtained. The reasons for the difference between the experimental and theoretical results of contact force distribution are analyzed. It is considered that the small difference in sphere size and the stability of loading mode are the key factors affecting the test results. In addition, the linear correlation between the test value of contact force peak value and the theoretical value of contact force peak value is established, and the correction coefficient of the test value of contact force peak value is obtained by using the theoretical value of contact force peak value, and the method of determining the correction coefficient is put forward. Finally, by means of contact compression test, the failure mode of lightweight spherical materials is determined to be brittle cracking after large plastic deformation. It is considered that the maximum tensile stress determined by Hertz contact theory is not suitable for the strength criterion of a single lightweight spherical material. The contact force corresponding to the elastic limit of a single lightweight spherical material is put forward as the calculation control standard for the maximum filling height of the lightweight spherical material roadbed, and the maximum filling height of the subgrade is obtained by calculating the maximum filling height of the subgrade. Can meet the general roadbed filling height requirements.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U416.1

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