粒料基层设计方法与永久变形控制指标研究

发布时间：2018-05-09 18:37

  本文选题：粒料基层 + 永久变形　； 参考：《东南大学》2015年博士论文

【摘要】：限制粒料基层沥青路面结构的永久变形是路面结构设计的一项基本要求,也是此类路面结构设计方法普遍选取的一种损坏模式。本文主要针对粒料层的永久变形开展研究,目的是提出控制粒料层永久变形的设计指标,并建立相应的控制模型,主要工作包括以下几个方面：首先,选定141种典型路面结构进行粒料层应力水平分析,并对半刚性基层+粒料层倒装结构与粒料基层全柔性结构两种典型结构43种组合进行分析,对各结构层厚度与模量变化对粒料层应力水平影响进行分析,得到了各因素对粒料层应力状态的影响规律,提出了适宜的粒料层厚度范围与下卧层模量要求；确定了粒料基层典型应力水平σ1=100-250kPa, σ3=0～100kPa,主应力比在σ1/σ3=1.2～7.9,主要分布在1.4～5.1之间,从而确定了动态模量加载序列和永久变形试验加载条件。第二,以动态模量和CBR为级配碎石材料设计性能参数,研究了不同含水量、不同应力状态与不同压实度对动态模量的影响,得到了不同级配的影响规律以及不同层位粒料层模量取值范围；控制关键筛孔不同级配动态模量与CBR的变化,对级配碎石级配组成进行优化,得到了关键筛孔控制通过率。采用贝雷法对级配参数进行了嵌挤状态判定,得到了骨架嵌挤状态下CA的取值范围。第三,分析了主应力比、围压、级配及含水量对永久变形特性的影响规律,永久变形在1000次加载时已基本形成,20000次以后变形累积非常缓慢；依据试验结果对M-E模型参数进行了回归分析,另外,重新构建了基于应力状态的永久应变预估模型,并提出了含水量的调节系数；第四,论证了粒料层永久变形试验方案,采用30kPa、50kPa和70kPa三个围压,不同主应力比作为应力加载路径永久变形试验。分析了不同应力加载路径下的永久变形特性,并利用非线性统计回归和Perez,Ⅰ.模型对试验曲线进行了外延,确定以永久轴向应变速率不大于1×10-5/10-3(每个加载周期)时,做为粒料的永久变形处于A-B区域边界(安定限界)的判断准则。最后,计算了162种典型路面结构的粒料层永久变形量,分析了各路面结构层所占路面结构总永久变形量的比例,拟定了6mm做为临界永久变形量标准,确定室内试验临界永久应变为0.03,调整了粒料层永久变形占总变形的比例。利用外延永久变形试验曲线,得到临界塑性应变标准对应的标准荷载作用次数。提出了以应力比(垂直应力与围压)作为控制粒料基层永久变形的设计指标,建立了基于4.75mm关键筛孔的永久变形的控制模型。本文以安定理论作为理论基础,寻找粒料永久变形处于塑性安定与塑性蠕变时的临界应力比,建立粒料基层永久变形处于塑性安定状态下的控制模型,使设计的路面结构在荷载周期内处于塑性安定状态,而不产生过大的永久变形,对粒料基层柔性路面结构设计与应用具有重要意义。
[Abstract]:Limiting the permanent deformation of asphalt pavement structure of granular base is a basic requirement of pavement structure design, and it is also a kind of damage mode which is generally selected by this kind of pavement structure design method. The purpose of this paper is to put forward the design index of controlling the permanent deformation of granular layer and to establish the corresponding control model. The main work includes the following aspects: first, 141 typical pavement structures are selected to analyze the stress level of granular layer, and 43 kinds of typical structures are analyzed, such as reverse structure of semi-rigid base granular layer and fully flexible structure of granular base. The influence of the thickness and modulus of each structure layer on the stress level of the granular layer is analyzed. The influence law of each factor on the stress state of the granular layer is obtained, and the suitable thickness range of the granular layer and the requirement of the underlying layer modulus are put forward. The typical stress levels of granular base are determined as 蟽 _ 1 ~ 100 ~ 250 KPA, 蟽 _ 3 ~ 0 ~ (100) KPA, the principal stress ratio is 蟽 _ 1 / 蟽 _ (3) 1.2g ~ (7.9), and the main distribution is between 1.4 ~ 5.1. The loading sequence of dynamic modulus and the loading condition of permanent deformation test are determined. Secondly, the effects of different water content, different stress state and different compaction degree on dynamic modulus are studied with dynamic modulus and CBR as the design parameters of graded macadam. The influence law of different gradation and the value range of modulus of different horizon granular layer are obtained, the dynamic modulus of different gradation of key sieve hole and the change of CBR are controlled, the gradation composition of gradation gravel is optimized, and the control pass rate of key sieve hole is obtained. Bayley method is used to judge the inlay state of gradation parameters, and the value range of CA in skeleton embed state is obtained. Thirdly, the effects of principal stress ratio, confining pressure, gradation and water content on the permanent deformation characteristics are analyzed. After 1000 times of loading, the accumulation of deformation is very slow. According to the test results, the parameters of M-E model are regressed, in addition, the permanent strain prediction model based on stress state is constructed, and the adjustment coefficient of water content is put forward. Three confining pressures, 30 KPA 50 KPA and 70kPa, were used to test the permanent deformation of stress loading paths with different principal stress ratios. The characteristics of permanent deformation under different stress loading paths are analyzed, and nonlinear statistical regression and Perez, 鈪，

本文编号：1866973