Evaluation of the Karst Collapse Susceptibility of Subgrade Based on the AHP Method of ArcGIS and Prevention Measures: A Case Study of the Quannan Expressway, Section K1379+300-K1471+920

In order to solve the problem of geological disasters caused by karst collapse in the K1379+300-K1471+920 section of the Quannan Expressway reconstruction and expansion, the evaluation of karst collapse susceptibility in the study area was carried out, and the corresponding prevention measures are put forward. Firstly, by identifying and determining the susceptible factors of karst collapse in the study area, three criterion layers, including the basic geological conditions, karst collapse impact, and human activities were selected, with a total of seven susceptible factors. The analytic hierarchy process (AHP) was used to assign values to each factor, and the evaluation model of karst collapse susceptibility in the study area was established. Then, using the spatial analysis function of ArcGIS, the seven susceptible factor partition maps were superimposed according to the evaluation model, and the evaluation map of the karst collapse susceptibility was obtained. The study area was divided into five levels of susceptibility: extremely susceptible areas (2.64–2.81), susceptible areas (2.43–2.64), somewhat susceptible areas (1.88–2.43), non-susceptible areas (1.04–1.88), and non-karst areas (0.51–1.04). The length of the extremely susceptible area is 11.90 km, 12.85% of the total length of the route, and the susceptible area, somewhat susceptible area, non-susceptible area, and non-karst area account for 25.05%, 39.54%, 11.01%, and 11.55% of the total length, respectively. The research results of the karst collapse susceptibility in the area are consistent with the actual situation. Finally, combined with the research results, prevention measures for karst collapse are put forward, which provide a reference for the prevention and mitigation of disaster in engineering construction.