单向拉伸应力状态下沥青混合料强度和刚度特性

Stress and stiffness characteristics of asphalt mixture under uniaxial tensile stress state

为了解单向拉伸应力状态下沥青混合料的强度、刚度特性及破坏原因,进行不同加载速度的直接拉伸动回弹模量、静回弹模量及强度试验,揭示沥青混合料强度、回弹模量、破坏应变、应变能等参数随加载速度的变化规律。建立初始开裂对应的各个力学参数与加载速度之间的幂函数关系,并从破坏机理上将材料设计与结构层的设计相统一。研究结果表明:在单轴拉伸试验中,沥青混合料的动、静回弹模量随加载速度的增大而呈幂函数增大,且动回弹模量随着温度的升高而降低;进行不同加载速度的破坏试验时,试件的初始开裂应变基本保持稳定,且表现为拉应变破坏特征,故拉应变是导致沥青混合料发生破坏的原因,用第二强度理论作为直接拉伸条件下的破坏准则较合适。

In order to study stress and stiffness properties,as well as failure reason of asphalt mixture under uniaxial tensile stress state,static resilient modulus tests,dynamic resilient modulus tests and strength tests with various loading rates were carried out.Based on the tests,the change law of mechanics parameters such as strength,modulus,failure strain and strain energy of asphalt mixture with loading rates were revealed.The power function relations among various mechanics parameters corresponding to initial crack and loading rates were established.Material design and structural layer design were unified in failure mechanism.The results show that the dynamic and static resilient modulus increase with the increase of loading rate as power function.Besides,the dynamic modulus decreases with the increase of temperature.The initial cracking strain of specimen almost keeps stable at various loading rates,and presents tensile strain failure.So,tensile strain is the main factor leading to failure,and the second strength theory can be used as failure criterion for direct tensile condition.