沥青混凝土冻融断裂特性与损伤机理研究

Study on Freeze-Thaw Fracture Characteristics and Damage Mechanism of Asphalt Concrete

目的研究冻融循环对沥青混凝土抗剪强度参数、弹性模量及断裂性能的影响规律,为防治季冻区路面冻融灾害提供科学依据。方法采用冻融循环试验和三轴压缩试验测定沥青混凝土的抗剪强度参数变化规律;采用半圆劈裂试验研究冻融循环对沥青混凝土断裂性能的影响规律;基于ABAQUS数值计算软件XFEM扩展元程序模拟沥青混凝土裂隙动态扩展规律,并对开裂过程的损伤耗散能进行动态采集;基于Griffith断裂理论推导出拉-剪组合状态下沥青混凝土Ⅰ型、Ⅱ型断裂应力强度因子计算方法,揭示裂隙倾角对沥青混凝土裂隙扩展路径的影响机理。结果沥青混凝土的抗剪强度、弹性模量及弯拉强度均随着冻融循环次数增加出现降低的现象;沥青混凝土车辙深度随冻融循环次数增多而增长;沥青混凝土的抗高温变性能力随循环性次数增多而逐渐弱化。结论椭圆形断裂强度准则可较好地描述冻融效应下沥青混凝土复合裂隙断裂韧性特征,所提出的应力强度因子可较好地描述沥青混凝土开裂特征;开展本研究对于季冻区沥青混凝土路面冻融灾害防治具有重要意义。

The influence of freeze-thaw cycles on the shear strength parameters,elastic modulus and fracture performance of asphalt concrete is studied to provide a scientific basis for the prevention and control of freeze-thaw disasters of pavement in seasonal frozen area.The change rules of shear strength parameters of asphalt concrete are determined by freeze-thaw cycle experiment and triaxial compression test,and the influence of freeze-thaw cycles on the fracture performance of asphalt concrete is studied by semicircle splitting experiment.Based on the ABAQUS software XFEM,the dynamic crack propagation law of asphalt concrete is simulated,and the damage dissipation energy in the cracking process is collected dynamically.Based on Griffith fracture theory,the calculation methods of mode Ⅰ and mode Ⅱ fracture stress intensity factors of asphalt concrete under tension shear combination state are derived,and the influence mechanism of crack inclination angle on crack propagation path of asphalt concrete is revealed.The shear strength,elastic modulus and flexural tensile strength of asphalt concrete decrease with the increase of freeze-thaw cycles.The elliptical fracture strength criterion is better The proposed stress intensity factor can better describe the cracking characteristics of asphalt concrete.This study is of great significance for the prevention and control of freeze-thaw disaster of asphalt concrete pavement in seasonal frozen area.