Detecting landslides using remote sensing images involves converting gray level images into binary images. Given the complex background and non-uniform illumination in the regional remote sensing image, the commonly-used global thresholding methods are limited to interpret some landslides those hidden in the shadow. In this paper, we report on an enhanced image thresholding method for the noncontact detection of earthquake-induced landslides. The proposed method incorporates Monte-Carlo simulation into the local thresholding method, and essential issues, regarding complex illumination condition and uncertainties of determining block size in local thresholding method, are addressed. To better separate landslide candidate objects from the background, we incorporate Digital Surface Model (DSM) into the binary image, such that the interferences by built-up areas, terraces, and rivers can be significantly reduced considering the indicator of slope gradient. The described method has been tested using two benchmark tests, showing that the proposed method performs well dealing with the complex background and illumination condition. As a case study, we use the proposed method to detect landslides in a remote sensing image near Beichuan area after the 2008 Ms8.0 Wenchuan earthquake. Results demonstrate that the presented method interprets landslides resembling those of manually visual delineation.

This study aims to enhance the thermal resistance of asphalt mixture to cool asphalt pavement. Four kinds of asphalt mixtures were prepared by replacing basalt aggregate and limestone mineral powder with shale ceramsite (SC) and fly ash cenosphere (FAC), respectively. A series of experiments, including environment scanning electron microscope test, thermophysical parameter test, indoor irradiation test, shear strength test, and rutting test, were performed to verify the purpose of this study. The results show that using low‐density SC and FAC could produce lightweight asphalt mixtures, which had lower thermal conductivity than control asphalt mixture. The indoor irradiation test shows that the resultant asphalt mixtures had lower temperatures at the depth of lower than 4 cm. The addition of SC had a negative effect on the shear strength and dynamic stability of asphalt mixture. However, the two indicators increased due to the addition of FAC. The results presented in this study indicate that it is feasible to use lightweight aggregate to prepare low‐thermal‐conductivity asphalt mixture and use this kind of asphalt mixture to cool asphalt pavement.

Cement-treated aggregate mixture (CTAM) is widely used in many countries. To design this mixture using the vibration compaction method brings about many problems, such as serious inconsistencies in key parameters and strong vibration energy and noise imposed on adjacent buildings and people. This work presents a preliminary investigation of the use of Superpave gyratory compactor, which has been widely used to compact hot mix asphalt in the laboratory, to design CTAM. The 3-2-2 mode of the locking point was used to determine that the gyration compaction number N_design should be 105. The performances of the CTAM specimens prepared using gyration compaction were compared with those prepared using the Proctor and vibration compaction methods. Compared with Proctor and vibration compaction, gyration compaction had a smaller influence on aggregate degradation. Also, the optimal moisture content after gyration compaction was the minimum. The index values for maximum dry density, unconfined compressive strength and dry/temperature shrinkage coefficient after gyration compaction were between those for Proctor compaction and vibration compaction. It can be concluded that it is feasible to design CTAM by using a Superpave gyratory compactor to compact the mixture for 105 cycles.