基于室内结构试验的半刚性基层开裂数值仿真

为获得半刚性基层沥青路面结构的力学参数并分析其变化规律,设计并修建了大尺度半刚性基层沥青路面结构室内试槽,采用逐级加载方法进行结构内部应力、应变和模量的分层检测与试验.在试验数据的基础上,建立道路三维有限元模型,验证模型正确后进行了承载板数值仿真试验,分析了超载引起的半刚性基层开裂位置、起裂荷载、裂缝状态、应力强度因子和裂缝类型等问题.结果表明:当交通荷载超过起裂荷载时基层裂缝开始出现,沿路面横向基层层底靠近承载板中轴线位置的单元首先开裂,裂缝在行车荷载作用下进一步向上扩展而形成基层横向裂缝;半刚性基层荷载型开裂主要以I型张开型裂缝为主,应力强度因子大小取决于施加的荷载大小、裂缝长度和模型几何尺寸,应重点从合理设计基层厚度、改进基层材料性能和严格控制超载几个方面减少半刚性基层裂缝的产生.

Numerical Simulation of Semi-rigid Base Cracking Based on Structure Experiment

To obtain mechanical parameters of semi-rigid base asphalt pavement and analyze the variation law of mechanical parameters,large-scale asphalt pavement structure of semi-rigid base was designed and constructed in laboratory test tank to carry out structural internal stress,strain and modulus layered detection and experiment by stepwise loading method.Based on detection and experiment data,the 3D finite element model of road is set up.On the basis of model validation,numerical simulation of bearing plate test is carried out.The problems of crack initiation location,crack initiation load,crack status,stress intensity factor and crack type for reason of overloading are analyzed.The results show that cracks begin to appear when the traffic load exceeds the crack initiation load of semi-rigid base.The units which are along transverse direction of the base layer bottom of pavement and close to the centre axis line of the bearing plate crack first.Then cracks further extend up to the surface to form transverse cracks of base layer by the effect of traffic load.The cracks of semi-rigid base caused by load are mainly tensile cracks of type I.The value of stress intensity factor depends on the applied load size,crack length and model geometry.So measures should focus on the aspects of reasonable thickness design of base,improved performance of base material property and strict control of overloading to reduce formation of semi-rigid base cracks.