An experiment to evaluate the activity value of fly - ash used as a material for highway base course is also put forward , which can be adapted easily in highway engineering . based on field road investigation sa well as above results , all behaviors of low - activity fly - ash as highway semi - rigid base course material are tested , and the strength forming principles of lime - flyash mixtures are studied by means of dta , x - ray and sem analysis 在此基础上，通过大量室内试验结合试验路的研究，测定了低活性粉煤灰在半刚性基层中的各种路用性能；最后通过差热分析、 x一射线衍射分析及电镜微观结构分析就二灰混合料的强度形成原理进行了论述。
It is discussed that the load period , the damp ratio of pavement , the temperature of asphalt concrete , the resilient modulus of semi - rigid base , the material parameters and thickness of the composite foundation have influence on the vertical displacement , the radial stress of the base bottom and the sub - base bottom 具体探讨了荷载周期、道路结构体的阻尼比、沥青混凝土的温度、半刚性基层的回弹模量、复合地基的材料参数和厚度对特征点的竖向位移、基层和底基层层底径向应力的影响。
But , for the reflective cracking of asphalt pavement with half rigid base course and the cracking of the ac overlay above joints ( cracks ) in existing pcc pavement , the results of research show that the fatigue life of ac layer is mainly the life of the crack propagating stage . so the theory and method of fatigue destructive mechanics ( fatigue fracture mechanics and fatigue damage mechanics ) should be used to study and design the pavement structures instead of traditional fatigue mechanics 而对于半刚性基层反射裂缝和旧水泥混凝土路面沥青混凝土加铺层接缝(裂缝)开裂，研究发现，沥青结构层的疲劳寿命主要为裂缝扩展阶段的寿命，此时不应采用传统的疲劳力学进行研究和结构层设计，而应采用疲劳破坏力学(疲劳断裂力学和疲劳损伤力学)理论与方法。
