Crack disease is one of the most serious and common diseases in road detection. Traditional manual methods for measuring crack detection can no longer meet the needs of road crack detection. In previous work, the authors proposed a crack detection method for asphalt pavements based on an improved YOLOv5s model, which is a better model for detecting various types of cracks in asphalt pavements. However, most of the current research on automatic pavement crack detection is still focused on crack identification and location stages, which contributes little to practical engineering applications. Based on the shortcomings of the above work, and in order to improve its contribution to practical engineering applications, this paper proposes a method for segmenting and analyzing asphalt pavement cracks and identifying parameters based on image processing. The first step is to extract the crack profile through image grayscale, histogram equalization, segmented linear transformation, median filtering, Sauvola binarization, and the connected domain threshold method. Then, the magnification between the pixel area and the actual area of the calibration object is calculated. The second step is to extract the skeleton from the crack profile images of asphalt pavement using the Zhang–Suen thinning algorithm, followed by removing the burrs of the crack skeleton image using the connected domain threshold method. The final step is to calculate physical parameters, such as the actual area, width, segments, and length of the crack with images obtained from the crack profile and skeleton. The results show that (1) the method of local thresholding and connected domain thresholding can completely filter noise regions under the premise of retaining detailed crack region information. (2) The Zhang–Suen iterative refinement algorithm is faster in extracting the crack skeleton of asphalt pavement, retaining the foreground features of the image better, while the connected-domain thresholding method is able to eliminate the missed isolated noise. (3) In comparison to the manual calibration method, the crack parameter calculation method proposed in this paper can better complete the calculation of crack length, width, and area within an allowable margin of error. On the basis of this research, a windowing system for asphalt pavement crack detection, WSPCD1.0, was developed. It integrates the research results from this paper, facilitating automated detection and parameter output for asphalt pavement cracks.

Due to the great differences in geological environment characteristics and landslide disaster mechanism in different regions, the logical structure of each mathematical model is also different. It can only be determined through comparative research. Four improved algorithms based on Bayesian networkwere verified, and the error index was introduced to determine the algorithm with the best modeling effect. The landslide susceptibility probability of 774570 grids in Boshan District was calculated, and the landslide susceptibility distribution map of Boshan District was plotted. Based on the spatial superposition and grid calculator function of GIS, the landslide susceptibility assessment results of each model were compared.

To reveal the overtopping dam-break mechanism under extreme rainfall conditions and assess downstream flood risk, a series of dam-break flume tests, flood routing simulations and inundation risk assessments were conducted. Using the Hubuling Reservoir in Rizhao City, Shandong Province as a case study, a circulating extreme rainfall dam-break flume system with a controllable reservoir water level was constructed at a geometric similarity scale of 1:70. Four test conditions were designed: no rainfall and 50-year, 100-year and 2000-year rainfall return periods. Pore water pressure, earth pressure and water content sensors were embedded in critical dam sections to monitor real-time internal dynamic responses. The results show that, due to the combined effect of the highest rainfall intensity, rapid reservoir water-level rise, progressive infiltration-induced weakening and concentrated surface erosion, a dam-break occurs only under the 2000-year rainfall return period. The failure process is divided into four stages: initial infiltration, slope surface scour, overtopping initiation and rapid breach development. Based on dam-break parameters obtained by physical model tests, a two-dimensional numerical using HEC-RAS was conducted. The results show that, under the 2000-year rainfall return period, the flood reaches the downstream area at 80 min after dam failure. The maximum inundation area reaches 15.20 km² at 200 min, with a maximum inundation depth of 11.80 m and a maximum inundation duration of 144 h. By integrating the maximum inundation depth, inundation duration and land use conditions, the expected economic loss is estimated to be 690 million yuan. The results provide important support for dam-break early warnings, emergency management and disaster mitigation of similar small- and medium-sized reservoirs.