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In this work, the effect of mechanical damage on the thermal conductivity of granite was experimentally investigated. Granite samples were artificially damaged through cyclic loading and unloading tests, with the strain evolution and acoustic emission activity monitored simultaneously. P-Wave velocity of the damaged samples was tested to evaluate the damage effect. Thermal conductivity of the undamaged and damaged granite samples was tested using optical scanning method. The influence of mechanical damage on thermal conductivity was analyzed. Thermal conductivity difference in different testing directions was analyzed based on the experiment results in six scanning lines on the two surfaces of each disk sample. The results indicate that thermal conductivity of damaged samples reduced compared with that of the undamaged samples, while the thermal inhomogeneity factor increased. Thermal conductivity increased in water-saturated condition for both undamaged and damaged samples. The increased rate of damaged samples was bigger than that of the undamaged samples. The mechanical damage treatment caused the increase in the thermal conductivity difference in different testing directions. The difference decreased when samples were water saturated. Research results in this work can provide better knowledge to the evolution mechanism of thermal conductivity of engineering rock masses. [ABSTRACT FROM AUTHOR]

• Granites were artificially damaged through cyclic loading and unloading tests. • Temporal and spatial evolution of AE events were obtained. • 2D thermal conductivity images were obtained using optical scanning method. • Influence of mechanical damage on the distributed thermal conductivity was investigated. In this work, influences of mechanical damage and water saturation on the distributed thermal conductivity of granite were experimentally investigated. The samples were artificially damaged using uniaxial cyclic loading and unloading tests, with acoustic emission activity monitored simultaneously. 2D thermal conductivity images were obtained using optical scanning method for both undamaged and damaged samples in dry and saturated conditions. The results indicate that the overall thermal conductivity of the samples decreased after mechanical damage treatment, while the thermal inhomogeneity factor increased. The thermal conductivity difference distribution matched well with the spatial distribution of acoustic emission events. The overall thermal conductivity values increased after water saturation in vacuum condition for both undamaged and damaged samples. Thermal inhomogeneity factor didn't change significantly when undamaged samples were saturated, while thermal inhomogeneity factor of damaged samples decreased to a certain extent when samples were saturated. Research results in this work can provide better knowledge to the evolution mechanism of distributed thermal conductivity of engineering rock masses. [ABSTRACT FROM AUTHOR]

Vehicle overload is detrimental to bridges and traffic safety. This paper presents a study on the fatigue performance of typical reinforced concrete (RC) beams of highway bridges under vehicle overload. A definition method of vehicle overload and a construction method of overload ladder spectrum were first proposed based on traffic data acquisition, statistical analysis and structural calculation of the highway bridges in Guangzhou. A fatigue experimental method was also proposed with the three-ladder vehicle overload spectrum, and the fatigue tests of 15 RC beams strengthened with carbon fiber reinforced polymer (CFRP) under three loading levels were then carried out. The fatigue performance and the failure mechanism of the strengthened beams were presented and discussed, and two fatigue life prediction methods were proposed with the established modified Palmgren-Miner rule and the loading level equivalent method respectively. The results showed that the fatigue performance of the strengthened RC beams was severely degraded under overload ladder spectrum compared with that under constant amplitude cyclic load, and the life prediction methods were proved effective. [ABSTRACT FROM AUTHOR]