Background: Slope stability issue in red clay slopes during rainfall is one among the serious geoenvironmental disasters in China. In order to investigate the effect of long duration rainstorm on red-clay slopes, studies were conducted using Geostudio 2012. Five different rainfall-durations were applied to the slope and the results of coupled and uncoupled calculation modes were compared. Results and Conclusions: Results show that pore water pressure increased due to the dissipation of matric suctions and rise in water table during the rainfall period with the longer the rainfall duration, the larger the pore water pressure. The rate of change of pore water pressure was largest at rainfall durations of 4 days, among all the duration conditions considered for this study. After short duration rainstorms, a settlement of the surface of the slope was observed. However, in long duration rainstorms, the slope surface swelled in a non-uniform manner with the head of the slope experiencing the greatest expansion. Factor of safety exhibited a hysteresis during the calculation process, which was similar in trend with the pore water pressure as well, and it showed some amplitude during the calculation steps under the coupled calculation analysis as a result of the deformation and seepage force affecting each other on the performance of slope, especially for the slope stability.

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A bio-inspired two-scale image complementarity evaluation method is proposed. This novel multi-scale method provides a promising alternative for the performance assessment of image fusion algorithms. Moreover, it can also be used to compare and analyze the multi-scale difference of raw images. Two metrics are presented and used to assess the complementarity of fusion images in non-subsampled contourlet transform (NSCT) domains: visual saliency differences (VSDs) at the coarse scales and detail similarities (DSs) at the fine scales. Visual attention mechanism (VAM)-based saliency maps are combined with NSCT low-pass subbands to compute the VSDs, and linear correlation and contrast consistency-based DSs are compared in NSCT band-pass subbands. Five main multi-scale transform (MST)-based fusion algorithms were compared by using 30 groups of raw images that consist of four types of fusion images. Effects of NSCT filters and decomposition levels on evaluation results are discussed in detail. Furthermore, a group of color multi-exposure fusion images were also taken as examples to evaluate the complementarity of raw images. Experimental results demonstrate the effectiveness of the proposed method, especially for MST-based image fusion algorithms.

To investigate the shear strength and creep behavior of red-clay, laboratory experiments were conducted and the experimental results were compared with available theoretical creep models. Based on the consolidated drained (CD) triaxial tests results, internal friction angle and cohesion of the red clay soil were 21.5 • and 61.1 kPa, respectively. Three different confining pressures were set up to conduct the creep tests using multistage loading. The overall creep curves exhibited stepped stress-strain behavior. The creep behaviors were remarkably different from the soils tested with three distinct confining stresses. The post-creep failure mode of all the red clay samples exhibited drum shaped parabolic bulging with predefined shear planes. The experimental results were compared with three different types of creep models that used in practice. Among all of this verified results, Burger's model behaved betted than other models when fitting with the data collected from the experiment. An experimental result based empirical equation has also been developed which fits well with the experimental results obtained from the tested red clay samples. The results of this study will be helpful to evaluate the long-term shear strength and deformation of red clays subjected to various structural loadings.

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