Study On The Fatigue Performance Of Semi-rigid Base Course Materials

Based on the indoor test and existing results abroad and home, this paper develops a research on the fatigue property of four normal kinds of semi-rigid base materials. It presents test results of performance for three structural types of cement stabilized crushed rock including suspend-dense structure framework-dense structure and framework-pore structure, for two structural types of lime fly-ash stabilized crushed rock including suspend-dense structure and framework-dense structure, for cement stabilized soil and for cement stabilized gravel. By the probability analysis of Weibull on the results of fatigue test, the paper has a serial of fatigue prefigurative models. What's more, amends these models linking to the factual pavement performance. The test method of the bending fatigue performance under supporting condition and under soaking condition was put forward. Then the test was done and the influences was analyzed.Based on having indoor fatigue test, dynamic modulus deterioration laws of four common semi-rigid base materials have been studied. The paper has analyzed tension strain at the bottom of samples and presented the calculation method as well as value of the limit tension strain. Deterioration laws of each material modulus under fatigue loading have been analyzed. Modulus deterioration has three stages. Deterioration rate differs from stress level. The higher the stress level is, the greater the deterioration rate is. At last, the relationship between deterioration laws of dynamic modulus and structural type of semi-rigid base course materials was investigated. The paper summarized the selection method of modulus of semi-rigid base course materials in every country. Based on having indoor fatigue test, dynamic modulus deterioration laws of semi-rigid base materials have been studied. Modulus deterioration has three stages. The stage transition point and neutral point of modulus deterioration curve is proposed as the specific points. The deteriorated dynamic modulus is determined by the initial dynamic modulus. At last, the corresponding design effective modulus of the various working status of semi-rigid base course materials has been determined.