基于M-C准则的沥青路面破坏统一力学模式初步探讨

发布时间：2018-12-16 04:37

【摘要】：路面结构力学分析是道路工程中传统的研究课题,前人已经开展过大量的工作。但随着轮载的增加,以及路面结构组合形式的多样化,传统的路面结构破坏理论对于路面结构破坏的某些现象无法进行解释。如:路面表层破坏产生的大量Top-Down裂纹,在轮压作用下Top-Down裂纹开裂的拉应力是如何产生的?为什么基层强度大大提高之后路面表层的沥青层反而破坏的更快?研究路面结构中应力状态的复杂性需要新的思路。Mohr-Coulomb(M-C)准则是地质工程和岩土力学中常用的强度准则,本文尝试从学科交叉的角度,在传统的路面结构模型基础上利用M-C准则从应力的主应力分布形式的角度出发,探讨沥青路面结构应力的复杂性。主要工作包括:以弹性层状体系理论为基础,利用沥青路面结构的简化模型,分析了基层模量对沥青路面结构破坏的影响,确定了一种路面结构的控制指标-路面疲劳损伤潜在指数(APPDI),初步提出了路面结构破坏的统一力学模式;以现有的6条高速公路沥青路面为例,在有限元计算的基础上利用APPDI推断其路面破坏的力学模式,并与实际路面破坏进行对比分析验证,同时提出了几种路面结构对材料的强度要求;利用均匀设计安排参数组合对高模量基层路面结构应力分布进行了有限元计算,结合APPDI和莫尔圆分析了高模量基层路面结构中不同深度的应力状态,重点对比了不同位置不同深度剪应力的主应力组成方式,观察到高模量基层路面表层剪应力中主应力组成方式出现拉-压复合剪切现象。主要研究成果有:1)初步探讨了路面结构破坏的统一力学模式,发现最大拉应力或剪应力不全是路面结构最先破坏的位置,简单的以拉应力或剪应力大小作为路面结构控制指标是不准确的,本文提出了一种新的控制指标APPDI来解释路面结构破坏的机理。2)从新定义的控制指标APPDI分析三种典型沥青路面结构结构破坏形式依次为:柔性基层沥青路面表现为—以层底拉应力为主的层底弯拉破坏;半刚性基层沥青路面表现为—以轮迹边缘附近深1~5cm的压应力为主的剪切破坏(车辙)及轮外20cm左右处深度7~12cm以压应力为主的剪切破坏(车辙);刚性基层沥青路面表现为—面层表面轮迹边缘拉压共生作用的剪切破坏(Top-Down裂纹),其自上而下延伸扩展;并对三种典型路面结构破坏的面层材料强度做了分析,给出了材料强度范围要求。3)通过影响APPDI的材料参数内聚力c和抗拉强度σt,分析了沥青路面破坏与路面结构组成的影响:拉-压复合剪切状态的存在,使得路面在疲劳荷载作用下,有两种接近路面材料临界物态线的方式。拉-压复合剪切状态是TOP-DOWN裂纹与车辙破坏的重要诱因之一,疲劳状态下剪应力组成方式不同,对路面结构的疲劳寿命有重大影响;考虑到莫尔包络线是由内聚力c和抗拉强度σt控制,可以用高温内聚力c与抗拉强度σt或高温抗压强度σc作为路面材料剪切控制指标。
[Abstract]:The mechanical analysis of pavement structure is a traditional research subject in the road engineering, and a great deal of work has been carried out by the predecessors. However, with the increase of the wheel load and the diversification of the combination form of the pavement structure, the traditional pavement structure failure theory can not be explained to some phenomena of the pavement structure failure. For example, the large number of Top-Down cracks produced by the surface layer of the road surface, how is the tensile stress of the Top-Down crack crack under the action of the wheel pressure? Why is the asphalt layer on the surface of the road surface damaged more quickly after the strength of the base layer is greatly improved? It is necessary to study the complexity of the stress state in the pavement structure. The Mohr-Coulomb (M-C) criterion is the commonly used strength criterion in the geological engineering and rock and soil mechanics. The paper attempts to study the complexity of the structural stress of the asphalt pavement from the angle of the intersection of the subject and using the M-C criterion from the stress distribution form on the basis of the traditional pavement structure model. The main work includes: based on the theory of the elastic layered system, using the simplified model of the asphalt pavement structure, the influence of the base modulus on the structural failure of the asphalt pavement is analyzed, and the control index of the pavement structure-the potential index of the pavement fatigue damage (APDI) is determined. In this paper, a unified mechanical model of pavement structure failure is put forward. Based on the existing 6-bar asphalt pavement, the mechanical model of the pavement failure is inferred from the APDI on the basis of the finite element calculation, and the comparison and analysis are carried out with the actual pavement failure. At the same time, the strength requirement of several pavement structures on the material is proposed, and the stress distribution of the high-modulus base-layer pavement structure is calculated by means of the uniform design and parameter combination, and the stress states of different depths in the high-modulus base-layer pavement structure are analyzed in combination with the APDI and Molar circles. The principal stress composition of the shear stress at different positions is compared, and the tensile-pressure composite shear phenomenon is observed in the shear stress of the surface of the high-modulus base. The main research results are as follows: 1) The unified mechanical model of the pavement structure failure is preliminarily discussed. It is found that the maximum tensile stress or shear stress is not all the first damaged position of the pavement structure, and it is not accurate to use the tensile stress or the shear stress as the control index of the pavement structure. This paper presents a new control index APDI to explain the mechanism of pavement structure failure. The semi-rigid base asphalt pavement is characterized by the shear failure (rutting) dominated by the compressive stress of 1-5cm in the vicinity of the edge of the wheel track and the shear failure (rutting) with the depth of 7-12cm at the left and right of the wheel and the depth of 7-12cm. The rigid base asphalt pavement is characterized by the shear failure (Top-Down crack) of the surface wheel track edge pull-pressing symbiosis of the surface layer, and the top-down extension is extended; and the strength of the surface layer material which is damaged by the three typical pavement structures is analyzed, The influence of the failure of the asphalt pavement and the structure of the pavement structure is analyzed by the cohesive force c and the tensile strength equivalent t of the material parameters which influence the APDI: the existence of the tensile-pressure composite shear state is such that the road surface is under the action of the fatigue load, There are two ways to approach the critical state line of the pavement material. The tensile-pressure composite shear state is one of the important causes of the TOP-DOWN crack and rutting failure, and the shear stress composition in the fatigue state is different, which has a great effect on the fatigue life of the pavement structure; and considering that the Moire envelope is controlled by the cohesion c and the tensile strength, t, The high-temperature cohesive force c and the tensile strength equivalent t or the high-temperature compressive strength c can be used as the shear control index of the pavement material.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U416.217

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